WO2020097082A1 - Rain sensor - Google Patents
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- WO2020097082A1 WO2020097082A1 PCT/US2019/059873 US2019059873W WO2020097082A1 WO 2020097082 A1 WO2020097082 A1 WO 2020097082A1 US 2019059873 W US2019059873 W US 2019059873W WO 2020097082 A1 WO2020097082 A1 WO 2020097082A1
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- rain
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01W—METEOROLOGY
- G01W1/00—Meteorology
- G01W1/14—Rainfall or precipitation gauges
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
- G01H11/08—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means using piezoelectric devices
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H3/00—Measuring characteristics of vibrations by using a detector in a fluid
- G01H3/10—Amplitude; Power
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01W—METEOROLOGY
- G01W1/00—Meteorology
- G01W1/02—Instruments for indicating weather conditions by measuring two or more variables, e.g. humidity, pressure, temperature, cloud cover or wind speed
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01W—METEOROLOGY
- G01W1/00—Meteorology
- G01W1/08—Adaptations of balloons, missiles, or aircraft for meteorological purposes; Radiosondes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01W—METEOROLOGY
- G01W1/00—Meteorology
- G01W1/10—Devices for predicting weather conditions
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J2001/4266—Photometry, e.g. photographic exposure meter using electric radiation detectors for measuring solar light
- G01J2001/4285—Pyranometer, i.e. integrating over space
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R17/00—Piezoelectric transducers; Electrostrictive transducers
- H04R17/02—Microphones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/01—Electrostatic transducers characterised by the use of electrets
- H04R19/016—Electrostatic transducers characterised by the use of electrets for microphones
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
Definitions
- hydrometeors e.g., rain
- hydrometeor characteristics e.g., volume, rate, size distribution, etc.
- Weather data are used by numerous entities such as government agencies and a variety of industries for analysis and informational purposes. For example, some industries that typically require accurate weather data include power traders, utility companies, insurance agencies, agriculture, and research institutions. Moreover, accurate data are critical for weather forecasting and meteorology, as well as for alternative energy planning and/or monitoring. In particular, collecting data related to hydrometeors (e.g., rain) is important for food production, loss prevention, climate study, and urban planning.
- hydrometeors e.g., rain
- rain sensor technologies have been developed. These sensors vary in their detection mechanism as well as their resolution and accuracy. At a general level, the main types of rain sensors either physically collect raindrops to measure accumulated water volume or weight directly or measure individual hydrometeor impacts and calculate aggregate accumulation.
- a common type of rain sensor is a rain gauge, e.g., a waterproof collection receptacle having a known cross-sectional area that is used to collect rainfall.
- a disadvantage of a rain gauge is that it requires a user to read accumulated rainfall and to empty it after each rain event. While these actions can be automated with sensors and actuation, such technologies require moving parts.
- a tipping bucket rain gauge which is a type of rain gauge in which collected water is funneled into a separate receptacle that tips, empties, and resets once a known amount of rainfall has occurred. Each tip is counted to provide a measure of total rain volume.
- the shortcomings of the tipping bucket include accuracy, installation, and longterm maintenance. Further, performance of the tipping bucket receptacles is impacted by mechanical issues (e.g., dirty or frozen bearings and clogged inlet funnels caused by animals or dead plant material) that can prevent tipping or that cause“false” tips to be counted in the absence of rain or complete filling.
- disdrometers capture information on individual hydrometeors and can differentiate between different types of hydrometeors.
- the most common disdrometers use a photogate or related optical technique to identify the size and velocity of individual hydrometeors and compute the rain rate over an amount of time.
- Some disdrometers compute other parameters such as snowfall rate, mixed precipitation characteristics, and can identify graupel or hailstones. However, they require excessive power to and are expensive.
- Some technologies comprise use of a piezoelectric device to measure the kinetic energy of rain drops. See, e.g., Madden, Phytopathology 88: 950 (1998); Forster, Journal of Atmospheric and Oceanic Technology 21: 179 (2004).
- piezoelectric devices require physically attaching the piezoelectric component to a detection plate. Accordingly, the performance of the rain gauge depends both on the method of attachment and on the specifications of the other components. In these technologies, the dynamic response of the piezoelectric sensor is greatly influenced by direct attachment to a surface.
- piezoelectric component attaching the piezoelectric component to a surface, e.g., using adhesive, fusing, or bolting, affects the“spring” and“damper” dynamic relations between the sensor and the detection surface area. Consequently, the complexities of these relationships have to be taken into account. For example, corrections in measurements using piezoelectric elements are often made to account for Poisson’s Ratio Effect and Shear Lag Effect. See, e.g., Sirohi, Journal of Intelligent Material Systems and Structures 11: 246 (2000). Further, piezoelectric materials are temperature dependent, which introduces errors into measurements of rain while in use in a recording environment experiencing changes in temperature. Piezoelectric devices can exhibit up to a 50% change in capacitance over their range of operation and, consequently, devices comprising piezoelectric elements have additional components and complexity to correct for these variations and thus have increased failure modes.
- acoustic signals are transmitted through a fluid (e.g., liquid or air) to a transducer. See, e.g., Kinnell, Journal of Applied Meteorology 11: 691 (1972). These instruments are limited to measurements of low rainfall intensities, exhibit position- dependent sensor sensitivities, and suffer errors from variations in drop velocity and angle of impact caused by wind currents. Additional technologies comprising detection of acoustic signals to detect individual raindrop impacts include those described, e.g., in U.S. Pat. Nos. 7,249,502; 7,286,935! 8,448,507; 6,892,580; 9,244,192; and U.S. Pat. App. Pub. No.
- hydrometeor e.g., rain
- an automated hydrometeor sensor Provided herein are embodiments of an automated hydrometeor sensor.
- the technology provides a device and/or apparatus that has no moving parts and that does not comprise a piezoelectric component.
- the technology comprises“piezoelectric component-free” embodiments.
- the technology provides a device and/or apparatus that does not comprise a sensing element attached to a surface impacted by rain (e.g., as in some devices comprising a piezoelectric element).
- the technology comprises“surface-attached sensor-free” embodiments.
- the technology comprises use of an electret microphone that does not require phantom power. Accordingly, in some embodiments, the technology does not comprise a condenser microphone (e.g., a microphone that requires phantom power). Thus, in some embodiments, the technology comprises“condenser microphone -free” embodiments. In various embodiments, the technology has a lower cost than comparable technologies and needs minimal or no maintenance. In some embodiments, the
- hydrometeor sensor technology is integrated with a wind sensor, e.g., to correct
- hydrometeor characteristics e.g., hydrometeor mass, hydrometeor size, hydrometeor volume, accumulated hydrometeor mass or volume, hydrometeor impact velocity, hydrometeor impact force, hydrometeor impact angle, hydrometeor impact momentum.
- the hydrometeor sensor technology is integrated with a hail sensor, e.g., to correct determinations of non-hail (e.g., rain drop) characteristics (e.g., drop mass, drop size, drop volume, accumulated drop mass or volume, drop impact velocity, drop impact force, drop impact, angle, drop impact momentum).
- the technology provides a rain sensing apparatus comprising a hollow sonde; and a transducer.
- the rain sensing apparatus further comprises a stalk upon which is mounted said transducer.
- the technology is not limited in the shape of the sonde.
- the sonde is a sphere.
- the technology is not limited to a sonde that is a sphere and includes embodiments comprising a sonde of any shape.
- the technology comprises embodiments in which a sonde is essentially, substantially, or functionally a sphere.
- the sonde is an ellipsoid, a spheroid, a toroid, a disc, a prism, a conical section, a portion of a sphere or spheroid, or a portion or section of any of the foregoing (e.g., a half-sphere, etc.)
- a portion of the sonde is removed and replaced with another component (e.g., a cone component, (e.g., comprising a“drum head” component and a cone body that tunnels sound to the transducer)).
- a cone component e.g., comprising a“drum head” component and a cone body that tunnels sound to the transducer
- the technology is not limited in the material from which the sonde is made.
- the sonde is made of a metal that provides the“bell-like” attributes of the sonde as discussed herein (e.g., steel, stainless steel, aluminum, copper, bronze, tin, a metal alloy, etc.)
- the sonde has a diameter of from 100 to 500 mm (e.g., 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 260, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, or 500 mm).
- the sonde shell is 0.5 to 5 mm (e.g., 0.5, 0.6, 0.7,
- the sonde has a characteristic frequency of 6 to 10 kHz (e.g., 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, or 10.0 kHz).
- 6 to 10 kHz e.g., 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, or 1
- the transducer is an electret, piezo, or condenser microphone.
- the technology comprises a piezoelectric component but the piezoelectric component is not in direct contact with any surface of a structure or component upon which hydrometeors impact. That is, in some embodiments comprising a piezoelectric component, the piezoelectric component is separated from the structure or component upon which hydrometeors impact by an air gap or similar gap. In some embodiments comprising a piezoelectric component, the piezoelectric component detects sound waves propagated through a non ⁇ solid (e.g., gas) from a component upon which hydrometeors impact to the piezoelectric component.
- a non ⁇ solid e.g., gas
- the transducer is placed approximately 20 to 80 mm (e.g., 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,
- the transducer is placed on the vertical axis of the sonde. In some embodiments, the transducer is placed approximately 25 to 76 mm (e.g., 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,
- the microphone is placed at a position within the sonde that is measured relative to the size (e.g., diameter (D) and/or the radius (R)) of the sonde.
- the microphone is placed at a position that is on the vertical axis of the sonde and is positioned at a distance that is approximately 0.05 x D to 0.95 x D above the sonde center (e.g., a distance that is approximately 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95 x D above the sonde center).
- the microphone is placed at a position that is on the vertical axis of the sonde and is positioned at a distance that is approximately 0.2 x D to 0.8 x D above the sonde center (e.g., a distance that is approximately 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8 x D above the sonde center).
- the microphone is placed at a position that is on the vertical axis of the sonde and is positioned at a distance that is approximately 0.3 x D to 0.7 x D above the sonde center (e.g., a distance that is approximately 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7 x D above the sonde center).
- the microphone is not placed on the vertical axis of the sonde, e.g., in some embodiments the microphone is placed approximately 0.05 x D to 0.95 x D away from the sonde center (e.g., a distance that is approximately 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.76, 0.8, 0.85, 0.9, or 0.95 x D away from the sonde center in any direction).
- the sonde comprises a limited rain-sampling area (e.g., in some embodiments, the sonde comprises a cone element, comprising a“drum head” and a cone that tunnels sound to the transducer).
- the apparatus further comprises a solar radiance sensor.
- the technology provides a method of determining a rain rate, the method comprising providing an apparatus as described herein (e.g., comprising a hollow sonde and
- determining a rain rate from the acoustic power data or acoustic energy data comprises producing a statistical parameter from a distribution of acoustic power data or acoustic energy data.
- processing the real-time acoustic signal comprises sampling an analog voltage to produce a digital time varying signal.
- processing the real-time acoustic signal comprises demodulating an amplitude modulated signal. In some embodiments, processing said realtime acoustic signal comprises applying an envelope to the digital time varying signal. In some embodiments, processing said real-time acoustic signal comprises downsampling the digital time varying signal. In some embodiments, determining a rain rate from the acoustic power data or acoustic energy data comprises using a correlation between the aggregate signal of multiple droplet strikes and rain rate. In some embodiments, determining a rain rate from the acoustic power data or acoustic energy data comprises using a power function to correlate between the aggregate signal of multiple droplet, strikes and rain rate.
- methods further comprise normalizing the acoustic power and/or acoustic energy detected by an apparatus as described herein.
- normalizing the acoustic power and/or acoustic energy detected by an apparatus as described herein uses an empirical measurement of the acoustic power and/or acoustic energy in a normal rain (e.g., having a maximum drop size of approximately 4.0 or 5.0 mm in diameter (e.g., having a distribution of drop sizes between approximately 0.5 mm and 4.0 or 5.0 mm in diameter (e.g., a diameter of approximately 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6,
- normalizing the acoustic power data and/or acoustic energy data uses a normalization constant based on the maximum microphone signal detected in a normal rain.
- methods comprise correcting the acoustic power data and/or acoustic energy data for wind velocity (e.g., as detected by a weather ⁇ sensing device as described in U.S. Pat. Nos. 9,846,092 and 9,958,346, each of which is incorporated herein in its entirety).
- Some embodiments relate to use of an apparatus comprising a sonde and transducer to detect, rain (e.g., rain rate, rain accumulation).
- rain e.g., rain rate, rain accumulation
- FIG. 1 is a schematic drawing of an embodiment of a rain-sensing apparatus 100 as described herein, e.g., comprising a sonde 110 and a microphone 130 on a stalk 120 inside a volume 160 inside the sonde.
- FIG. 2 is a schematic drawing showing a raindrop 280 and a raindrop 281 impacting an embodiment of a rain-sensing apparatus as described herein.
- FIG. 3 is a schematic drawing showing a raindrop 380 and a raindrop 381 impacting an embodiment of a rain-sensing apparatus as described herein.
- FIG. 4A is a plot showing the acoustic signal (arbitrary units measuring microphone signal) versus time for a series of rain drops impacting the sonde of a rain detection apparatus according to the technology as described herein.
- the acoustic signal was recorded by a microphone inside the sonde as described herein.
- the rain droplets were released from a height of 1.2 m and impacted the sonde at a frequency of 1 Hz at the“north pole” of the sonde (e.g., where the vertical axis intersects the sonde surface).
- the test droplets had a diameter of 2.419 ⁇ 0.089 mm (variation of 3.70%) and a mass of 7.41 ⁇ 0.82 mg (variation of 11.00%).
- FIG. 4B is a plot showing a single pulse from FIG. 4A.
- FIG. 4C is a plot showing the fine structure of the signals shown in FIG. 4A and
- FIG. 4B is a diagrammatic representation of FIG. 4B.
- FIG. 5 is a plot of the acoustic power (Pa) versus time for a single drop impacting the sonde of an apparatus as described herein.
- the acoustic power provides one acoustic signature of a single rain drop impacting an embodiment of the apparatus described herein.
- the peak excursion of the acoustic power derived from the audio signal is referred to as the “P -value”.
- FIG. 6 is a plot of the Acoustic energy (“E a ”, numerical summation of the acoustic power signal from a single drop impact, or generally over a period of time) versus time for a single drop impacting the sonde of an apparatus as described herein.
- the acoustic energy shown in FIG. 6 (E a ) provides one acoustic signature of a single rain drop impacting an embodiment of the apparatus described herein.
- FIG. 7 is a plot showing demodulation of acoustic power (black dots). The absolute values of peaks are identified and intermediate points are estimated by interpolation (white dots).
- FIG. 8 is a plot showing transformation of the demodulated signal by an envelope (“airplane”) filter.
- the demodulated signal is shown in black dots and the signal after transformation by the envelope filter is shown in white dots.
- the microphone was positioned on the Z-axis at various distances (in mm) below (- values) and above (+ values) the equator (see, e.g., Figure l).
- FIG. 11A is a plot of the simulated acoustic power (Pa) as a function of time for constant, rain rates of 2 mm/hour and 10 mm/hour. The signal shows peaks for individual rain drop impacts recorded by the device.
- FIG. 11B is a plot of the simulated acoustic power (Pa) as a function of time for a constant rain rate of 100 mm/hour. The signal shows peaks for individual rain drop impacts recorded by the device.
- FIG. 12 is a plot of rain rate versus time for rain rate determined using a power law function and the acoustic signal processed as described herein (solid line) and the rain rate as determined by a disdrometer (dashed line).
- FIG. 13 is plot of cumulative rain measured over time as determined using the power law function and the acoustic signal processed as described herein (black line) and the rain rate as determined by a disdrometer (grey line) and a tipping bucket rain gauge (circles).
- FIG. 14 is a schematic drawing of an embodiment of a rain-sensing apparatus comprising a cone piece 200 to provide an apparatus with a limited rain-sensing area.
- FIG. 15 is a schematic drawing of an embodiment of a rain-sensing apparatus comprising a pyranometer or other solar radiance sensor near the microphone area (210).
- the apparatus further comprises a portion (a“drum head” section) 220 that is optically clear, translucent, or otherwise allows transmission of solar radiation to the pyranometer or other solar radiance sensor.
- a“drum head” section is optically clear, translucent, or otherwise allows transmission of solar radiation to the pyranometer or other solar radiance sensor.
- Other numbered components are as described herein for FIG. 1.
- FIG. 16 is a plot of the logarithm (base 10) of the summed absolute value of transducer signal versus wind speed for an embodiment of a rain detection device as described herein.
- FIG. 17 is a plot of the logarithm (base 10) of the absolute value of the transducer signal over a 10-second time interval versus the logarithm (base 10) of the summed absolute value of the transducer signal over a 10-second time interval.
- FIG. 18A is a plot of the rainfall for multiple different rain storms recorded with a particular rain detection device (84ebl8eb2a8b) as a function of the number of 10 second intervals of this rainfall rate that the acoustic power represents as corrected for wind.
- FIG. 1813 is a plot of the rainfall for multiple different rain storms recorded with a particular rain detection device (84ebl8eb2a8b) as a function of the number of 10 second intervals of this rainfall rate that the acoustic power represents as uncorrected for wind.
- FIG. 19 is a plot of rainfall rate determined by six different rain detection devices as described herein versus rainfall rate determined by a co-localized tipping bucket measurement device.
- hydrometeors e.g., rain
- hydrometeor characteristics e.g., volume, rate, size distribution, etc.
- the term“or” is an inclusive“or” operator and is equivalent to the term“and/or” unless the context clearly dictates otherwise.
- the term “based on” is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise.
- the meaning of“a”,“an”, and“the” include plural references.
- the meaning of“in” includes“in” and“on.”
- a rain volume refers to a volume of rain.
- a rain volume is an absolute measure of volume (e.g., expressed in units of volume).
- a rain volume is expressed as a function of another measurement (e.g., volume per unit time, volume per unit of surface area).
- Rain volume expressed in units of volume per surface area are simplified in some embodiments to a one dimensional measurement of rain accumulation, e.g., as provided by a conventional rain gauge. In some embodiments, this measurement is the vertical height of rainfall column on a flat-bottom vessel.
- a rain rate refers to a volume of rain impacting a surface as a function of time.
- a rain rate is an instantaneous measurement of rain rate at a discrete time.
- a rain rate is a summed (e.g., integrated) measure of total rain accumulation over a specified time interval.
- a rain rate is an averaged measure of rain accumulation over a specified time interval.
- the term“rain size distribution” refers to a distribution of rain drop sizes for rain drops impacting a surface during a specified time period.
- the measurements of drop size distribution comprises counting drops and placing them into categories or bins based on volume, size (e.g., diameter), and/or mass.
- the term“disdrometry” or“disdrometric” refer to the size distribution of hydrometeors (e.g., rain drops).
- welding refers to a component constructed from an assembly of smaller components, e.g., that are joined by welding the smaller components.
- the suffix“-free” refers to an embodiment of the technology that omits the feature of the base root of the word to which“-free” is appended. That is, the term “X-free” as used herein means“without X”, where X is a feature of the technology omitted in the“X-free” technology. For example, a“calcium -free” composition does not comprise calcium, a“mixing-free” method does not comprise a mixing step, etc.
- an“increase” or a“decrease” refers to a detectable (e.g., measured) positive or negative change in the value of a variable relative to a previously measured value of the variable, relative to a pre-established value, and/or relative to a value of a standard control.
- An increase is a positive change preferably at least 10%, more preferably 50%, still more preferably 2-fold, even more preferably at least 5-fold, and most preferably at least 10-fold relative to the previously measured value of the variable, the pre- established value, and/or the value of a standard control.
- a decrease is a negative change preferably at least 10%, more preferably 50%, still more preferably at least 80%, and most preferably at least 90% of the previously measured value of the variable, the pre- established value, and/or the value of a standard control.
- a“rain event” is a weather condition leading to precipitation, preferably measurable precipitation.
- the term“rain event” refers to hydrometeor impacts (e.g., rain) incident on embodiments of the devices described herein, but is not limited to hydrometeor impacts (e.g., rain) impacts and thus includes other weather-related forces and phenomena.
- weather data refers to any measurable or quantifiable weather or meteorological condition or phenomena, such as, for example, rainfall, precipitation, temperature, wind speed, cloudiness, barometric pressure, snowfall, sleet, hail, and ice.
- precipitation levels refers to any amount of water, from any source, preferably atmospheric weather, such as rain, sleet, snow, and hail, for example. Precipitation is generally related to rainfall, and is calculated, in some
- the term“real-time” refers to the time in which reporting of events or recording (e.g.,“acquiring”) of events is simultaneous (or substantially or effectively simultaneous) with the event or occurring at the same time (or substantially or effectively at the same time) as another event and/or occurrence.
- acoustic power or“P-acoustic” or“P a ” refers to the instantaneous value (in counts) of the demodulated acoustic signal recorded by a transducer (e.g., a microphone).
- the term“P-value” refers to the peak acoustic power (in counts) derived from the acoustic signal produced by a single hydrometeor (e.g., a single rain drop).
- the acoustic power recorded for a single hydrometeor has a signature shape that typically comprises a sharp spike in the acoustic power up to the peak value (P-value) followed by an exponential decay.
- the term“acoustic energy” or“E a ” refers to integrated acoustic power occurring over a specific time range.
- the technology relates to a rain-sensing apparatus comprising a sonde, a stalk, and a microphone.
- the technology relates to a rain sensor as shown in Figure 1, e.g., comprising a sonde 110, a stalk 120, and a microphone 130.
- the sonde is a sphere. In some embodiments, the sonde is hollow. However, the technology is not limited to a sonde that is a sphere and includes embodiments comprising a sonde of any shape. For example, the technology comprises embodiments in which a sonde is essentially, substantially, or functionally a sphere. In some embodiments, the sonde is an ellipsoid, a spheroid, a toroid, a disc, a prism, a conical section, a portion of a sphere or spheroid, or a portion or section of any of the foregoing (e.g., a half-sphere, etc.)
- the sonde is made of steel (e.g., stainless steel). In some embodiments, the sonde is made of another metal (e.g., aluminum, copper, bronze, tin, a metal alloy, etc.) In some embodiments, the material is chosen to provide acoustic, sonic (e.g., bell-like) characteristics to the sonde. For example, in some embodiments, the material is chosen to produce sounds of a particular frequency and/or range of frequencies when impacted by a hydrometeor (e.g., rain).
- a hydrometeor e.g., rain
- the sonde has a center and axes passing through the center.
- Terms known in the art for spherical geometry apply to embodiments comprising spherical sondes.
- a geodesic connects two points on the surface of the sphere.
- a great circle (or orthodrome) of a sphere is the intersection of the sphere and a plane that passes through the center point of the sphere.
- a great circle is the largest circle that can be drawn on any given sphere. Any diameter of any great circle coincides with a diameter of the sphere, and therefore all great circles have the same center and circumference as each other.
- the spherical sonde has a vertical axis (e.g., an axis aligned with a gravity vector (e.g., an axis passing through the center of the sphere and essentially passing through the center of the Earth)).
- An equator is a particular great circle that is perpendicular to the vertical axis.
- the“Z dimension” or“Z axis” as defined with respect to a sphere is defined by (e.g., is coincident with and/or is parallel to) the vertical axis of a spherical sonde.
- Figure 1 shows an embodiment of a rain sensing apparatus 100 comprising a sonde 110, a stalk 120, and a microphone 130.
- the vertical axis 150, which passes through the center 190, and the equator 140 are also shown for reference.
- the sonde is hollow. Accordingly, in some embodiments, the sonde comprises a“shell” having a thickness and defining an internal volume 160. Further, the shell separates the internal volume 160 from the external environment. In some embodiments, the shell has a thickness of approximately 0.5 mm to 5 mm (e.g.,
- the shell has a diameter of approximately 100 to 500 mm (e.g., 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, or 500 mm).
- the technology is not limited by this range of diameters and thicknesses and contemplates other diameters and thicknesses that operate according to the principles discussed herein.
- embodiments provide that the sonde produces a sound having a characteristic frequency when impacted by a hydrometeor (e.g., rain).
- a hydrometeor e.g., rain
- the sonde produces a characteristic frequency when impacted by a rain drop that is in the range from 6 kHz to approximately 10 kHz (e.g., approximately 6.0, 6.1, 6.2,
- the characteristic frequency is a function of the material, diameter (e.g., volume), and shell thickness of the sonde. In some embodiments, the characteristic frequency is a function of environmental variables such as temperature, atmospheric pressure, humidity, composition of the atmosphere, composition of impacting hydrometeors, phase of impacting hydrometeors (e.g., liquid rain or solid hail or sleet, etc.)
- the rain sensing apparatus further comprises a transducer that converts sound into an electrical signal, e.g., a sensor of acoustic signals.
- the rain sensing apparatus comprises a microphone.
- the technology is not limited in the type of microphone that is used.
- the microphone is an electret microphone.
- the microphone is a condenser microphone.
- the technology comprises use of an electret. microphone that, does not require phantom power. Accordingly, in some embodiments, the technology does not. comprise a condenser microphone (e.g., a microphone that requires phantom power) and is thus, in some embodiments, a“condenser microp hone - free” rain sensing apparatus.
- the microphone is a piezoelectric microphone.
- the piezoelectric element does not detect impacts of a surface directly (e.g., by attachment to the impacted surface), but instead detects acoustic signals propagated from the contacted surface (e.g., the sonde shell) through a non-solid phase (e.g., a gas (e.g., air)) to the microphone in the internal volume.
- a non-solid phase e.g., a gas (e.g., air)
- the microphone is a ribbon microphone, a carbon microphone, fiber optic microphone (see, e.g., Paritsky and Kots (1997)“Fiber optic microphone as a realization of fiber optic positioning sensors” Proceedings of the International Society for Optical Engineering (SPIE). 10th Meeting on Optical Engineering in Israel. 3110: 408-09, incorporated herein by reference), a laser microphone, or a microelectrical-mechanical system (MEMS) microphone.
- a ribbon microphone e.g., Paritsky and Kots (1997)“Fiber optic microphone as a realization of fiber optic positioning sensors” Proceedings of the International Society for Optical Engineering (SPIE). 10th Meeting on Optical Engineering in Israel. 3110: 408-09, incorporated herein by reference
- SPIE Standard Society for Optical Engineering
- MEMS microelectrical-mechanical system
- the microphone detects acoustic signals produced by impacts of hydrometeors on the external surface of the sonde (e.g., external surface of the sonde shell). Transformation, processing, and analysis of the acoustic signal provides information characterizing the rain drops impacting the sonde.
- the microphone is not placed at the center of the sphere so that the distances from the microphone to different points on the sonde surface are different and thus the signal contains information about the location of drop impact, on the sonde.
- the microphone is placed at. a position that is on the vertical axis of the sonde and approximately 20 to 80 mm above the sphere center. In some embodiments, the microphone is placed at a position that is on the vertical axis of the sonde and approximately 25 to 75 mm above the sphere center. In some embodiments, the microphone is placed at a position that is on the vertical axis of the sonde and approximately 30 to 70 mm above the sphere center.
- the microphone is placed at a position that is on the vertical axis of the sonde and approximately 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
- the microphone is not placed on the vertical axis of the sonde, e.g., in some embodiments the microphone is placed approximately 20, 21, 22, 23, 24, 25,
- the microphone is placed at the sphere center.
- the microphone is placed at a position within the sonde that is measured relative to the size (e.g., diameter (D) and/or the radius (R)) of the sonde.
- the microphone is placed at a position that is on the vertical axis of the sonde and is positioned at a distance that is approximately 0.05 x D to 0.95 x D above the sonde center (e.g., a distance that is approximately 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.65, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.96 x D above the sonde center).
- the microphone is placed at a position that is on the vertical axis of the sonde and is positioned at a distance that is approximately 0.2 x D to 0.8 x D above the sonde center (e.g., a distance that is approximately 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8 x D above the sonde center).
- the microphone is placed at a position that is on the vertical axis of the sonde and is positioned at a distance that is approximately 0.3 x D to 0.7 x D above the sonde center (e.g., a distance that is approximately 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7 x D above the sonde center).
- the microphone is not placed on the vertical axis of the sonde, e.g., in some embodiments the microphone is placed approximately 0.05 x D to 0.95 x D away from the sonde center (e.g., a distance that is approximately 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.76, 0.8, 0.85, 0.9, or 0.95 x D away from the sonde center in any direction).
- Weather sensing device integrating rain sensing technology
- the rain sensing technology (e.g., apparatus or components thereof) is integrated into a weather-sensing device as described in U.S. Pat. Nos. 9,846,092 and 9,958,346, each of which is incorporated herein by reference in its entirety. See Example 1.
- the rain sensing technology is integrated into a weather sensing device, e.g., a device to sense, measure, and/or collect weather data, atmospheric data, environmental data, etc., such as wind speed and/or direction;
- a weather sensing device comprises a drag generating component (optionally comprising a shaft) attached to a grounded fixture by one or more stress or strain sensing devices and/or stress or strain components.
- the strain produced on the drag generating component is sensed by the two or more strain or stress sensing devices (e.g., a load cell and/or a component comprising a load cell) attached to the drag generating component (optionally comprising a shaft).
- the technology is not limited in the shape of the drag generating component.
- the drag generating component is a sphere. In some embodiments, the drag generating component is spheroid, ellipsoid, cylindrical, or polyhedral. In some embodiments, the drag generating component of the weather sensing device (e.g., for detecting wind speed and/or direction and/or for detecting hydrometeor speed and/or direction) is also the sonde of the rain detection technology, e.g., one component of the weather sensing device is both the sonde and the drag generating component (e.g., a sonde/drag generating component).
- the drag generating component (optionally comprising a shaft) is attached by one or more stress sensing devices to a rigid grounded fixture. That is, in some embodiments, one or more stress sensing devices is directly attached to the drag generating component (optionally comprising a shaft) and the one or more stress sensing devices is directly attached to the rigid grounded fixture. In some embodiments, one or more stress sensing devices is directly attached to a shaft (connected to a drag generating component) and the one or more stress sensing devices is directly attached to the rigid grounded fixture.
- the strain or stress sensing devices are, e.g., strain gages, semiconductor strain gages, piezo crystals, resistive elements, capacitive elements, inductive elements, acoustic sensors, optical sensors, load cells, or the like.
- the stress or strain detected by each strain or stress sensing device is converted to an electrical signal, e.g., a voltage, a current, a resistance, etc., by the electronic components of the device.
- the analog signal is further converted into a digital signal, e.g., by an analog/digital (A/D) converter.
- A/D analog/digital
- a microprocessor is configured to receive and process a digital signal.
- the weather sensing device comprises a sound sensor (e.g., microphone) that finds use in correcting data describing hydrometeor impacts.
- the strain sensing devices produce data that are input into an algorithm or model for determining the magnitude and/or direction vector of the weather related phenomena (e.g., hail, wind) detected by the device.
- the relative strains on each strain or stress sensing device are used to calculate the magnitude and/or direction vector of the weather related phenomena detected by the device.
- sound data are used to correct the magnitude and/or direction vector of the weather related phenomena (e.g., hydrometeor impact and/or wind).
- the vector is determined in a two-dimensional coordinate system! in some embodiments, the vector is determined in a three-dimensional coordinate system.
- the sensors reside within the coordinate system in which the vector is determined. In some embodiments, the sensors are used to establish the coordinate system used to determine the vector in two-dimensions or three-dimensions.
- one or more of the strain or stress sensing devices is a load cell or a component comprising a load cell (e.g., a component connecting the drag generating component to the grounded fixture).
- a load cell comprises strain or stress sensing devices.
- Load cells are widely used off-the-shelf components and are available commercially (e.g., from HBM, Inc., Marlborough, MA).
- load cells comprise one or more strain gages and, in some embodiments, comprise a hole or a cutout.
- the drag generating component (optionally comprising a shaft) is attached by one or more load cells to a rigid grounded fixture, e.g., in some embodiments, one or more stress sensing devices is directly attached to the drag generating component and/or shaft and the one or more stress sensing devices is directly attached to the rigid grounded fixture.
- the load cells comprise a design and/or construction that impart in the load cells the ability to sense stress and/or strain.
- the load cells are designed to be sensitive only to bending moments along their longitudinal axis.
- a load cell comprises one or more holes or cutouts, e.g., perpendicular to the longitudinal axis of the load cell.
- the technology is not limited to the exact configuration of the load cell. There are numerous different ways to position the load cells and provide a hole in the beam to obtain the desired strain characteristics.
- a load cell is used to measure torsion around the longitudinal axis and/or a force applied along the
- load cells are sensitive to longitudinal loading and are mounted vertically. In some embodiments, load cells are sensitive to torsional loading and are mounted underneath the shaft or on the periphery of the shaft, e.g., to measure forces inducing a twist in the shaft. In some embodiments, a load cell is mounted on the middle of the shaft. In some embodiments, a load cell is mounted directly to the drag generating component, e.g., to provide embodiments of the device that do not comprise a shaft. The technology is applicable to devices comprising any number of strain sensing devices (e.g., load cells).
- the analysis comprises calculating the force on the drag generating component, e.g., by adding the forces (e.g., as represented by force vectors) experienced by the strain sensing devices.
- the forces e.g., as represented by force vectors
- three force vectors are added to determine the force (e.g., magnitude and angle) imparted on the drag generating component.
- the weather-sensing apparatus measures wind velocity (e.g., speed and direction) and detects individual hydrometeors (e.g., hail). While, in some embodiments, the rain sensing apparatus described herein is integrated into a weather - sensing apparatus (e.g., as described in U.S. Pat. Nos. 9,846,092 and 9,958,346), the technology is not limited to such embodiments. Thus, in some embodiments, the rain sensing apparatus comprises a sonde, stalk, and a microphone as described herein and does not necessarily comprise a drag-generating component, stalk or tube, strain sensors (e.g., load cells), and/or other components of the weather-sensing apparatus as described in U.S. Pat. Nos. 9,846,092 and 9,958,346.
- wind velocity e.g., speed and direction
- individual hydrometeors e.g., hail
- the rain sensing apparatus described herein is integrated into a weather - sensing apparatus (e.g., as described
- the technology described herein comprises using the microphone as described herein to accept or reject candidate hydrometeor (e.g., hail) impacts.
- candidate hydrometeor e.g., hail
- the previous approximately 2 ms (1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3,
- 2.4, 2,5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4,3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 ms) of microphone data are saved along with the following 10 ms (e.g., 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1,
- the spike of the microphone signal is aligned with the peak of the
- the hydrometeor impact according to the speed of sound.
- the speed of sound In some embodiments, the
- hydrometeor e.g., hail
- the candidate hydrometeor e.g., hail
- a verified hydrometeor e.g., hail
- a sample that changes at least 1,000 to 100,000 bits e.g., approximately 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, 90000, or 100000 bits
- a 16-bit converter e.g., approximately 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7,
- the microphone and/or hydrometeor impact data are passed on for additional processing as described herein.
- the technology provides a rain-sensing apparatus comprising a limited rain-sampling area ( Figure 14).
- limiting the rain-sampling area results in fewer observed drops, effectively filtering out droplet signatures that fall outside of the sampling area.
- limiting the area of rain detection provides a technology for quantifying individual raindrops on the sonde and thus producing more disdrometric information, e.g., in some embodiments mimicking and/or providing some functions of a conventional disdrometer.
- a rain- sensing apparatus comprising a limited rain- sampling area comprises a sonde (e.g., a hollow sonde) comprising a hole and a cone piece installed in the hole.
- the cone piece comprises a“drum head” (200) that is at the sonde surface and a cone body that is installed around the top of the microphone, tunneling sound waves to the microphone.
- installing the cone piece comprises screwing in the cone piece (e.g., comprising a cone body and drum head).
- the cone piece comprises the microphone for ease of replacement.
- the drum head is made from a material different than the sonde! in some embodiments, the drum head is made from the same material as the sonde. In some embodiments, the drum head provides different, acoustic properties than the sonde. The seal between the cone/drum head and metal shell would be important for weatherization and acoustic dampening properties.
- an apparatus provided herein comprises a pyranometer or other solar radiance sensor.
- the pyranometer or other solar radiance sensor is placed near the microphone area (210) and the drum head is an optically clear plastic or other diffuse material (220) that allows the cone piece assembly to be a dual rain / solar radiation sensor.
- rain and solar radiance measurements are combined for cost savings and to provide a dual predictor of storm advancement.
- the microphone area (210) includes solar photovoltaic cells to provide power to the unit.
- the technology further provides methods of detecting rain (e.g., individual drops, rain accumulation, rain rate, etc.).
- methods comprise providing an apparatus as described herein.
- the technology provides methods of detecting rain, e.g., individual rain drops, accumulated rainfall, and/or rain rate using an apparatus as described herein.
- methods comprise obtaining, making, using, and/or providing a rain detection apparatus as described herein (e.g., a rain-sensing apparatus comprising a sonde and a transducer and, in some embodiments, a stalk).
- methods comprise obtaining, making, using, and/or providing one or more components of a rain detection apparatus as described herein (e.g., one or more first components comprising a sonde or a transducer or, in some embodiments, a stalk) for combination with additional components of a rain detection apparatus as described herein (e.g., one or more second components comprising a sonde or a stalk or, in some embodiments, a transducer) to provide a complete rain sensing apparatus.
- a rain detection apparatus as described herein
- additional components of a rain detection apparatus e.g., one or more second components comprising a sonde or a stalk or, in some embodiments, a transducer
- methods comprise detecting the impact of one or more rain drops on the surface of a sonde of an embodiment of an apparatus as described herein. In some embodiments, methods comprise determining the angle of impact of a rain drop on the surface of the sonde. In some embodiments, methods comprise determining the position of impact of a rain drop on the surface of the sonde. In some embodiments, a vector is determined describing the motion of a rain drop at the moment of impact with the sonde.
- methods comprise determining the impact energy transferred to the sonde by a rain drop impact. In some embodiments, methods comprise recording and/or acquiring an acoustic signal produced by the impact of a rain drop with the sonde. In some embodiments, methods comprise recording and/or acquiring an acoustic signal having an oscillation in the range of from approximately 6 to approximately 10 kHz (e.g., approximately 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, or 10.0 kHz).
- methods comprise recording and/or acquiring an acoustic signal in a frequency range that encompasses the natural, primary frequency of the sonde (e.g., approximately 6 to approximately 10 kHz (e.g., approximately 6.0, 6.1, 6.2,
- methods comprise calculating, producing, and/or recording a time -varying signal (e.g., a digital time -varying signal produced by sampling an analog output of the apparatus (e.g., apparatus transducer) at a frequency of approximately 25 to 100 kHz (e.g., 25, 26, 27, 28, 29. 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43.
- a time -varying signal e.g., a digital time -varying signal produced by sampling an analog output of the apparatus (e.g., apparatus transducer) at a frequency of approximately 25 to 100 kHz (e.g., 25, 26, 27, 28, 29. 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43.
- methods comprise recording and/or acquiring an analog voltage (e.g., from the transducer). In some embodiments, methods comprise sampling the analog voltage at 25 to 50 kHz (e.g., at 25.0, 26.1, 26.2, 25.3, 25.4, 25.5, 25.6, 25.7, 25.8,
- the analog voltage is sampled at 32 or 44.1 kHz to produce a digital time varying signal. In some embodiments, the analog voltage is sampled at 8, 12, 16, 24, 32, 64, 128, or 256 bits of resolution.
- methods comprise recording and/or acquiring an analog voltage (e.g., from the transducer). In some embodiments, methods comprise sampling the analog voltage at. 25 to 100 kHz (e.g., 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
- the analog voltage is sampled at 32, 44.1, or 96 kHz to produce a digital time varying signal. In some embodiments, the analog voltage is sampled at 8, 12, 16, 24,
- methods comprise detecting the location of impact of a rain drop on the sonde surface (Q) using the analog and/or digital signal. In some embodiments, methods comprise detecting the impact angle of a raindrop on the sonde surface (iy 2 ) using the analog and/or digital signal. In some embodiments, methods comprise detecting a time of impact of a raindrop on the sonde surface using the analog and/or digital signal.
- methods comprise detecting and/or measuring the velocity, speed, direction, acceleration, momentum, size, volume, mass, composition, or shape of a raindrop impacting the sonde surface. In some embodiments, methods comprise
- methods comprise calculating the velocity, speed, direction, acceleration, momentum, size, volume, mass, composition, or shape of a raindrop impacting the sonde surface. In some embodiments, methods comprise calculating a vector describing the velocity, momentum, direction, and/or acceleration of a raindrop impacting the sonde surface. In some embodiments, methods comprise detecting, determining, and/or calculating an amount, of impact (e.g., kinetic) energy transferred from a raindrop to the sonde.
- an amount, of impact e.g., kinetic
- the methods comprise providing the digital time varying signal as a datastream in real time.
- methods comprise analyzing the digital time varying signal (datastream) in real time.
- the datastream is analyzed by a component of the apparatus configured to compute statistical parameters that correspond to rain and characterize rain.
- the datastream is sent to a remote component and said remote component is configured to compute statistical parameters that correspond to rain and characterize rain. Accordingly, methods comprise computing statistical parameters describing rain (e.g., rain rate, rain accumulation, etc.) from the datastream.
- methods comprise analyzing (e.g., in real time) a datastream, e.g., provided by the time-varying digital signal. In some embodiments, methods comprise calculating a statistical parameter from the datastream, e.g., provided by the time-varying digital signal, that correspond and/or correlate to rainfall, raindrops, and/or characteristics of rainfall and/or raindrops (e.g., location of impact of a rain drop on the sonde surface (Q), impact angle of a raindrop on the sonde surface (y 2 ), rain rate, raindrop velocity, raindrop speed, raindrop direction, raindrop acceleration, raindrop momentum, raindrop size, raindrop volume, raindrop mass, raindrop composition, raindrop shape, raindrop velocity vector, raindrop momentum vector, raindrop direction vector, raindrop acceleration vector, and/or amount of impact (e.g., kinetic) energy transferred from a raindrop to the sonde).
- a statistical parameter from the datastream e.g., provided by the time-varying digital signal
- methods comprise calculating a mean, median, range, maximum, minimum, mode, distribution, standard deviation or other statistical treatment of rainfall and/or raindrop characteristics (e.g., location of impact of a rain drop on the sonde surface (Q), impact, angle of a raindrop on the sonde surface (y 2 ), rain rate, raindrop velocity, raindrop speed, raindrop direction, raindrop acceleration, raindrop momentum, raindrop size, raindrop volume, raindrop mass, raindrop composition, raindrop shape, raindrop velocity vector, raindrop momentum vector, raindrop direction vector, raindrop acceleration vector, and/or amount of impact (e.g., kinetic) energy transferred from a raindrop to the sonde).
- raindrop characteristics e.g., location of impact of a rain drop on the sonde surface (Q), impact, angle of a raindrop on the sonde surface (y 2 ), rain rate, raindrop velocity, raindrop speed, raindrop direction, raindrop acceleration, raindrop momentum, raindrop size, raindrop volume, raindrop mass, raindrop composition, raindrop shape, raindrop
- methods comprise detecting, measuring, and/or calculating an acoustic signature of rain, e.g., a characteristic signature of a rain drop impact or a plurality of rain drop impacts on the sonde.
- methods comprise recording a pulse train produced by the impacts of rain drops on the sonde.
- methods comprise detecting, measuring, and/or calculating an oscillation produced by a rain drop or a plurality of rain drops, e.g., corresponding to a natural frequency of the sonde (e.g., at a frequency of approximately 6-10 kHz (e.g., 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10 kHz)).
- methods comprise analyzing an oscillation produced by a rain drop or a plurality of rain drops to detect an amplitude modulation (AM) of the primary ring frequency. In some embodiments, methods comprise analyzing an oscillation produced by a rain drop or a plurality of rain drops to identify a characteristic AM signature of the rain drop or a plurality of rain drops.
- AM amplitude modulation
- the characteristic AM signature of the rain drop or a plurality of rain drops comprises components that correlate with a parameter of an individual impacting drop, e.g., location of impact of a rain drop on the sonde surface (Q), impact angle of a raindrop on the sonde surface (y2), raindrop velocity, raindrop speed, raindrop direction, raindrop acceleration, raindrop momentum, raindrop size, raindrop volume, raindrop mass, raindrop composition, raindrop shape, raindrop velocity vector, raindrop momentum vector, raindrop direction vector, raindrop acceleration vector, and/or amount of impact (e.g., kinetic) energy transferred from a raindrop to the sonde.
- a parameter of an individual impacting drop e.g., location of impact of a rain drop on the sonde surface (Q), impact angle of a raindrop on the sonde surface (y2), raindrop velocity, raindrop speed, raindrop direction, raindrop acceleration, raindrop momentum, raindrop size, raindrop volume, raindrop mass, raindrop composition, raindrop shape, raindrop velocity vector, raindrop momentum vector
- the methods comprise demodulating an amplitude modulated signal, e.g., to provide signals or data describing droplet size and/or position of droplet impact on the sonde surface. In some embodiments, the methods comprise demodulating an amplitude modulated signal, e.g., to provide signals or data describing mean droplet size and/or mean position of droplet impact on the sonde surface. In some embodiments, methods comprise transforming an acoustic signal (e.g., an amplitude modulated acoustic signal) to provide a demodulated signal.
- an acoustic signal e.g., an amplitude modulated acoustic signal
- transforming the acoustic signal comprises continuously applying demodulation to discrete points (e.g., using a running method), identifying peaks in the absolute value of signal intensity, and/or interpolating intermediate points between known peaks (e.g., according to Equation l).
- methods comprise calculating peak acoustic power (P-value) and/or acoustic energy (Ea).
- the demodulated signal comprises positive values corresponding to the instantaneous amplitude of the primary ring oscillation.
- methods comprise identifying the peak of the
- methods comprise assigning the peak acoustic power (P -value) to be the peak value of the demodulated signal.
- methods comprise numerically summing the acoustic power signature of a single drop impact.
- numerically summing the acoustic power signature of a single drop impact produces a curve that approaches an asymptotic value.
- methods comprise identifying the asymptotic value of the numerically summed acoustic power signature of a single drop impact.
- methods comprise assigning the total acoustic energy (E a ) associated with the drop impact to be the asymptotic value of the numerically summed acoustic power signature of a single drop impact.
- methods comprise calculating location of impact of a rain drop on the sonde surface (Q), impact angle of a raindrop on the sonde surface (y2), raindrop velocity, raindrop speed, raindrop direction, raindrop acceleration, raindrop momentum, raindrop size, raindrop volume, raindrop mass, raindrop composition, raindrop shape, raindrop velocity vector, raindrop momentum vector, raindrop direction vector, raindrop acceleration vector, and/or amount of impact (e.g., kinetic) energy transferred from a raindrop to the sonde using the total acoustic energy (Ea) associated with a raindrop impact.
- amount of impact e.g., kinetic
- methods comprise numerical summing the acoustic power of a single drop to provide a value for acoustic energy (Ea). In some embodiments, methods comprise detecting, measuring, and/or calculating peak acoustic power (P -value) of a single rain drop impact. In some embodiments, methods comprise detecting, measuring, and/or calculating acoustic energy (Ea) of a single rain drop impact.
- methods comprise analyzing the acoustic signal from raindrop impacts on a sonde of an apparatus provided herein.
- methods comprise obtaining an acoustic signal from raindrop impacts on the sonde (e.g., obtained by a microphone), digitizing the acoustic signal, and processing the digitized acoustic signal.
- processing the digitized acoustic signal comprises demodulating an amplitude modulated signal.
- demodulating an amplitude modulated signal comprises demodulating a real-time digital signal, e.g., by applying demodulation continuously (e.g., to discrete points using a running method).
- demodulating the amplitude modulated signal comprises identifying peaks in the absolute value of signal intensity. In some embodiments, demodulating the amplitude modulated signal comprises interpolating between known peaks. In some embodiments, processing the digitized acoustic signal comprises applying an envelope (e.g., an“airplane” filter) to the digital acoustic signal. In some embodiments, applying an envelope or filter to the digital acoustic signal comprises preserving the P-value and acoustic energy (E a ) of individual raindrop impacts.
- an envelope e.g., an“airplane” filter
- methods comprise applying an airplane filter using Equation 2, wherein k is adjusted to allow a sharp climb to preserve the initial peak (P-value) and the glide function ig is an exponential form with a time constant on the order of
- approximately 1 to approximately 10 milliseconds e.g., approximately 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6,
- applying an envelope or filter e.g., an airplane filter with a short glide provided by the glide function fg
- methods comprise preserving the fine (e.g., approximately 1-3 Hz) structure in the oscillation.
- applying an envelope or filter (e.g., an airplane filter with a long glide provided by the glide function fg) to the digital acoustic signal comprises removing the fine (e.g., approximately 1-3 Hz) structure in the oscillation.
- methods comprise using a long glide function to downsample the acoustic digital signal to approximately 3.2 Hz (e.g., approximately 2.5 to 4.0 Hz (e.g., approximately 2.6, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, or 4.0 Hz)), while still preserving the P-value and E a parameters.
- methods comprise downsampling the digital acoustic signal to approximately 3.2 Hz (e.g.,
- methods comprise filtering the real-time digital signal.
- methods comprise filtering the demodulated real-time digital signal.
- filtering the real-time digital signal comprises applying a running calculation on the real-time digital signal to generate a new series from the demodulated real-time digital signal.
- filtering the real-time digital signal comprises preserving the P-value of individual raindrop impacts. In some embodiments, filtering the real-time digital signal (e.g., the demodulated real-time digital signal) comprises preserving the acoustic energy (Ea) of individual raindrop impacts. In some embodiments, filtering the real-time digital signal (e.g., the demodulated real-time digital signal) comprises preserving the fine (e.g., approximately 1-3 Hz (e.g., approximately 1, 1.2,
- methods comprise calculating information about impact positions and/or water puddling from the fine (e.g., approximately 1-3 Hz (e.g., approximately 1, 1.2, 1.4, 1.6,
- filtering the real-time digital signal comprises removing the fine (e.g., approximately 1-3 Hz (e.g., approximately 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, or 3.0 Ilz)) structure in the oscillation.
- fine e.g., approximately 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, or 3.0 Ilz
- filtering the real-time digital signal comprises downsampling the real-time digital signal (e.g., the demodulated real-time digital signal) to produce a downsampled real-time digital signal.
- filtering the real-time digital signal comprises downsampling the real-time digital signal (e.g., the demodulated real-time digital signal) to produce a downsampled real-time digital signal a frequency of approximately 2.5 to 4.0 Hz (e.g., approximately 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4,
- downsampling the real-time digital signal comprises preserving the P-value and/or the Ea value.
- the downsampled real-time digital signal has a frequency of approximately 2.5 to 4.0 Hz (e.g., approximately 2.5, 2.6, 2.7, 2.8,
- the downsampled real-time digital signal preserves the P-value. In some embodiments, the downsampled real-time digital signal preserves the E a . In some embodiments, methods comprise determining droplet size from P -value. In some embodiments, methods comprise determining droplet size from E a . In some embodiments, methods comprise determining droplet impact position on the sonde from P- value. In some embodiments, methods comprise determining droplet impact position on the sonde from Ea.
- methods comprise determining rain rate.
- methods comprise detecting, measuring, and/or calculating a rain rate.
- methods comprise using signal processing and/or statistical analysis to determine rain rate from an acoustic signal.
- methods comprise using signal processing and/or statistical analysis to determine rain rate from a time- varying signal, a digital time -varying signal, a transformed acoustic signal, a demodulated acoustic signal, a filtered real-time digital signal, and/or a downsampled real-time digital signal.
- methods comprise using statistical treatment of an acoustic signal, a time -varying signal, a digital time -varying signal, a transformed acoustic signal, a demodulated acoustic signal, a filtered real-time digital signal, a downsampled real-time digital signal to determine rain rate.
- methods comprise identifying signal features (e.g., of the acoustic signal) that relate to the disdrometric characteristics of rainfall.
- methods comprise identifying signal features (e.g., of the acoustic signal) that correlate to a rain rate.
- methods comprise estimating rain rate over time.
- methods comprise calculating a rain accumulation using an estimated rainfall rate.
- methods comprise measuring, determining, and/or calculating dependence of the acoustic signal on droplet size and/or impact location on the sonde (Q).
- measuring, determining, and/or calculating rain rate comprises measuring, determining, and/or calculating the dependence of the acoustic signal on droplet size and/or impact location on the sonde (Q).
- measuring, determining, and/or calculating rain rate comprises measuring, determining, and/or calculating a P -value.
- measuring, determining, and/or calculating rain rate comprises measuring, determining, and/or calculating an Ea value.
- determining rain rate comprises providing an apparatus as described herein (e.g., comprising a sonde and a microphone). In some embodiments, methods of determining rain rate further comprise recording and/or acquiring the audio signal of raindrops striking the exterior of the sonde. In some embodiments, methods comprise recording and/or acquiring characteristic pulses in the acoustic signal, each pulse corresponding to a single droplet. In some embodiments, methods of determining rain rate comprise downsampling the real-time audio signal, e.g., to extract the envelope of each pulse. In some embodiments, methods comprise determining droplet size and/or droplet position using a relationship between pulse parameters and droplet size and/or a
- methods comprise determining rain rate using a statistical correlation between the aggregate signal of multiple droplet strikes (and/or parameters of the aggregate signal) and rain rate. In some embodiments, methods comprise determining rain rate without counting individual droplets. In some embodiments, methods comprise determining rain rate using a correlation that statistically averages droplet signatures.
- methods of determining a rain rate comprise determining statistically averaged quantities associated with the real-time acoustic signal or filtered acoustic power signal. In some embodiments, methods comprise applying statistical treatments to the time -varying acoustic power signal to obtain a measure of rain rate. In some embodiments, methods comprise determining statistical parameters from a
- time -varying acoustic power signal e.g., peak height, frequency in various frequency bands, mean amplitude, shape and length of the tail of the distribution, shape of the distribution, etc.
- methods comprise filtering an audio signal (e.g., an analog signal, a digital (e.g., discretized) acoustic signal, and/or a real-time digital (e.g., discretized) signal as described herein) to remove and/or minimize information outside the frequency range of interest (e.g., approximately 6 kHz to approximately 10 kHz (e.g., approximately 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, or 10.0 kHz) and/or approximately 25 to 100 kHz (e.g., 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 39
- filtering the audio signal comprises applying a digital filter (e.g., a finite impulse response notch filter) to frequency data (e.g., provided by an audio signal (e.g., an analog signal, a digital (e.g., discretized) acoustic signal, and/or a real-time digital (e.g., discretized) signal as described herein (e.g., the digital signal from an analog-to -digital converter sampling analog microphone data as described herein))) to remove and/or minimize information outside the frequency range of interest (e.g., approximately 6 kHz to approximately 10 kHz (e.g., approximately 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9,
- a digital filter e.g., a finite impulse response notch filter
- the acoustic power of the filtered signal described above is summed in the time domain over a defined window (e.g., from approximately 1 to 60 seconds (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
- a defined window e.g., from approximately 1 to 60 seconds (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
- the acoustic power of the filtered signal (e.g., filtered digital signal) is summed in the time domain over a defined window of approximately 10 seconds (e.g., 6.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 6.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2,
- the acoustic power of the filtered signal (e.g., filtered digital signal) is summed in the time domain over a defined window (e.g., approximately 10 seconds) and wind velocity over a second defined window (e.g., 20 to 300 seconds (e.g., 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 146, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 266, 270, 275, 280, 285, 290, 295, or 300 seconds)) is used to normalize the response.
- a defined window e.g., approximately 10 seconds
- wind velocity e.g., 20 to 300 seconds (e.g., 20, 25,
- the acoustic power of the filtered signal (e.g., filtered digital signal) is summed in the time domain over a defined window (e.g., approximately 10 seconds) and wind velocity over a second defined window (e.g., approximately 60 seconds) is used to normalize the response.
- a defined window e.g., approximately 10 seconds
- wind velocity over a second defined window e.g., approximately 60 seconds
- the rain rate is defined for the defined window over which the acoustic power of the filtered signal (e.g., filtered digital signal) is summed.
- the wind normalization factor (e.g., determined over the second defined window) is calculated and applied to the rain rate in the cloud (e.g., on a server, computer, virtual machine, etc. remote from the rain detection apparatus).
- a device-specific factory-defined calibration factor is applied in the cloud (e.g., on a server, computer, virtual machine, etc. remote from the rain detection apparatus) to the defined window over which the acoustic power is summed, which is then aggregated to a minute granularity. For example, for a defined window of 10 seconds for summing the acoustic power of the filtered signal (e.g., filtered digital signal) and a wind normalization factor calculated over a second defined window (e.g., approximately 60 seconds) of the wind readings, the normalization factor is calculated and the same normalization factor is applied to 6 separate 10-second rain rate readings.
- the technology is not limited to these particular time windows and includes longer or shorter defined windows for summing the acoustic power of the filtered signal (e.g., filtered digital signal) and second defined windows for calculating wind normalization factors.
- methods comprise applying peak-fitting to the filtered acoustic power signal (“P-Acoustic”). In some embodiments, methods comprise determining a rain rate by analyzing a distribution of P-Acoustic values. In some embodiments, methods comprise identifying individual peaks and their time of occurrence and amplitude (P -value), e.g., to provide a peak dataset. In some embodiments, methods comprise correcting peaks (e.g., for superposition). In some embodiments, methods comprise applying statistical treatments to a distribution of peak attributes (e.g., peak height, time of occurrence) of peaks in a peak dataset. In some embodiments, methods comprise determining an increase in rain rate by detecting an increase in P-values.
- P-Acoustic filtered acoustic power signal
- methods comprise determining a parameter (e.g., peak height, characteristic width, and/or frequency of occurrence within various bands) from a distribution of raw acoustic power signal data or filtered acoustic power signal data. In some embodiments, methods comprise calculating a rain rate using a parameter from a distribution of raw acoustic power signal data or filtered acoustic power signal data. In some embodiments, methods comprise deriving a blended acoustic parameter incorporating multiple characteristics of the acoustic power distribution. In some embodiments, determining rain rate comprises use of a correlation function using a blended acoustic parameter or a P -value as input.
- a parameter e.g., peak height, characteristic width, and/or frequency of occurrence within various bands
- methods comprise measuring instantaneous rain rate using a microphone acoustic signal and a power law function for calculating rain rate from the acoustic signal.
- methods comprise calibrating an apparatus as described herein, e.g., to improve accuracy of the apparatus for detecting rain drops, producing an acoustic signal, and/or for determining a rain rate.
- methods comprise real-time and/or post-processing numerical (or analytical) transformation to convert a raw datastream to a datastream that measures the rain rate with improved accuracy than the raw datastream.
- methods comprise correcting a rain rate, acoustic power, acoustic energy, and/or other measurement for wind (e.g., for wind velocity). In some embodiments, the speed and/or direction of one or more rain drops is/are corrected for wind. In some embodiments, the raw acoustic signal detected by the transducer is corrected for wind and in some embodiments, the processed signal (e.g., demodulated signal, summed signal, etc.) is corrected for wind. In some embodiments, methods comprise calibrating a rain detection device. In some embodiments, calibrating a rain detection device comprises providing (e.g., calculating, producing, determining) a normalization constant (e.g., a device -specific normalization constant).
- a normalization constant e.g., a device -specific normalization constant
- the normalization constant is based on the signal measured for a known rain rate.
- the known rain rate is a normal rain.
- a normal rain has a drop size distribution having a maximum drop size of approximately 4.0 mm in diameter.
- a normal rain has a drop size distribution between 0.5 and 4.0 or 5.0 mm in diameter (e.g., a diameter of approximately 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 mm).
- calibrating a rain detection device comprises determining a calibration factor (e.g., normalization constant) for each individual device after manufacture of the device (e.g., prior to delivery of the device).
- the device -specific calibration factor e.g., normalization constant
- the device -specific calibration factor is determined for a device and recorded for the specific device (e.g., using a unique identifier for the device that associates the normalization constant to the device and/or unique identifier).
- the device -specific calibration factor e.g., normalization constant
- the technology provides embodiments of systems comprising embodiments of the rain sensing apparatus described herein.
- Exemplary embodiments of a system comprise a rain sensing apparatus as described herein and a computer in communication with the apparatus.
- the system comprises a second apparatus as described herein in communication with the first apparatus and/or in communication with the computer.
- the systems furthermore comprise in some
- a software component for implementing algorithms and models used to calculate a rain rate based on the acoustic signals recorded and processed by one or more apparatuses installed in a geographic region.
- one or more of the apparatuses comprise a software component to calculate a rain rate.
- acoustic signals e.g., raw acoustic signal, filtered acoustic signal, and/or processed acoustic signal
- a computer comprises the software component to calculate a rain rate.
- a computer collects data from multiple apparatuses and comprises a software component to determine a rain rate based on the data collected from two or more apparatuses installed throughout a geographic region.
- the software component predicts future weather events.
- the systems further comprise an alerting component that issues an alert to a user or to another entity, e.g., for an action to be taken that is appropriate for the predicted weather events.
- System embodiments are implemented, for example, in a network of apparatuses and, in some embodiments, computers.
- a geographic area may be covered by a network or“micro-grid” of the apparatuses in communication with each other and, in some embodiments, a computer (e.g., a data server) to analyze the data from multiple apparatuses (e.g., apply a statistical analysis of the data).
- a computer e.g., a data server
- the systems provide a historical record, provide real-time monitoring, and/or provide predictions of weather events such as storms, temperature, front movements, rain, snow, pressure systems, wind speed, wind direction, ultraviolet radiation, heat index, air quality, dewpoint, ambient noise, etc.
- the apparatuses, methods, and systems described herein are associated with a programmable machine designed to perform a sequence of arithmetic or logical operations as provided by the methods described herein.
- some embodiments of the technology are associated with (e.g., implemented in) computer software and/or computer hardware.
- the technology relates to a computer comprising a form of memory, an element for performing arithmetic and logical operations, and a processing element (e.g., a microprocessor) for executing a series of instructions (e.g., a method as provided herein) to read, manipulate, and store data.
- a microprocessor is part of a system for collecting acoustic signals, processing acoustic signals, determining a rain rate, and/or modeling weather data.
- Some embodiments comprise a storage medium and memory components.
- Memory components find use in storing instructions (e.g., an embodiment of a process as provided herein) and/or data (e.g., a work piece such as an acoustic signal, processed or filtered acoustic signal, P-value, P-Acoustic, E a , etc.).
- instructions e.g., an embodiment of a process as provided herein
- data e.g., a work piece such as an acoustic signal, processed or filtered acoustic signal, P-value, P-Acoustic, E a , etc.
- Some embodiments relate to systems also comprising one or more of a CPU, a graphics card, and a user interface (e.g., comprising an output device such as display and an input device such as a keyboard).
- Programmable machines associated with the technology comprise conventional extant technologies and technologies in development or yet to be developed (e.g., a quantum computer, a chemical computer, a DNA computer, an optical computer, a spintronics based computer, etc.).
- the technology comprises a wired (e.g., metallic cable, fiber optic) or wireless transmission medium for transmitting data.
- a wired e.g., metallic cable, fiber optic
- some embodiments relate to data transmission over a network (e.g., a local area network (LAN), a wide area network (WAN), an ad-hoc network, the internet, etc.).
- a network e.g., a local area network (LAN), a wide area network (WAN), an ad-hoc network, the internet, etc.
- programmable machines are present on such a network as peers and in some embodiments the programmable machines have a client/server relationship.
- data are stored on a computer-readable storage medium such as a hard disk, flash memory, optical media, a floppy disk, etc.
- the technology provided herein is associated with a plurality of programmable devices that operate in concert to perform a method as described herein.
- a plurality of computers e.g., connected by a network
- may work in parallel to collect and process data e.g., in an implementation of cluster computing or grid computing or some other distributed computer architecture that relies on complete computers (with onboard CPUs, storage, power supplies, network interfaces, etc.) connected to a network (private, public, or the internet) by a conventional network interface, such as Ethernet., fiber optic, or by a wireless network technology.
- some embodiments provide a computer that includes a computer- readable medium.
- the embodiment includes a random access memory (RAM) coupled to a processor.
- the processor executes computer-executable program instructions stored in memory.
- processors may include a microprocessor, an ASIC, a state machine, or other processor, and can be any of a number of computer processors, such as processors from Intel Corporation of Santa Clara, California and Motorola Corporation of Schaumburg, Illinois.
- processors include, or may be in communication with, media, for example computer- readable media, which stores instructions that, when executed by the processor, cause the processor to perform the steps described herein.
- Embodiments of computer-readable media include, but are not limited to, an electronic, optical, magnetic, or other storage or transmission device capable of providing a processor with computer-readable instructions.
- suitable media include, but are not limited to, a floppy disk, CD-ROM, DVD, magnetic disk, memory chip, ROM, RAM, an ASIC, a configured processor, all optical media, all magnetic tape or other magnetic media, or any other medium from which a computer processor can read instructions.
- various other forms of computer-readable media may transmit or carry instructions to a computer, including a router, private or public network, or other transmission device or channel, both wired and wireless.
- the instructions may comprise code from any suitable computer-programming language, including, for example, C, C++,
- Computers are connected in some embodiments to a network.
- Computers may also include a number of external or internal devices such as a mouse, a CD-ROM, DVD, a keyboard, a display, or other input or output devices.
- Examples of computers are personal computers, digital assistants, personal digital assistants, cellular phones, mobile phones, smart phones, pagers, digital tablets, laptop computers, internet appliances, and other processor-based devices.
- the computers related to aspects of the technology provided herein may be any type of processor-based platform that operates on any operating system, such as Microsoft Windows, Linux, UNIX, Mac OS X, etc., capable of supporting one or more programs comprising the technology provided herein.
- Some embodiments comprise a personal computer executing other application programs (e.g., applications).
- the applications can be contained in memory and can include, for example, a word processing application, a spreadsheet application, an email application, an instant messenger application, a presentation application, an Internet browser application, a calendar/organizer application, and any other application capable of being executed by a client device.
- a computer or system provides diagnostic information about one or more weather sensing devices provided herein.
- a device, collection of devices, and/or system is able to self-check and/or report problems to a user.
- a computer or system provides automatic calibration of a device, system, or collection of devices.
- Example 1 Design of a rain sensing apparatus
- the technology relates to a rain sensor apparatus and related rain sensing methods and systems. Accordingly, during the development of embodiments of the technology described herein, an exemplary embodiment of a rain sensing apparatus was designed, produced, and tested.
- the exemplary rain sensor 100 comprised a sonde 110 (e.g., a hollow stainless steel sphere (e.g., approximately 200 mm in diameter and approximately 1.2 mm thick)), a stalk 120, and a microphone 130 (Figure l).
- the stalk extended into the volume 160 inside the sonde 110 and the microphone 130 was mounted at the top of the stalk 120.
- the stalk 120 was essentially and/or substantially aligned with the central vertical axis 160 of the sonde 110 and/or stalk 120.
- the microphone 130 was positioned above the equator 140 of the sonde 110, e.g., to maximize coupling of the rain sensor 100 to acoustic signals inside the volume 160 of the sonde 110.
- the technology is not limited to this placement of the microphone 130 - in some embodiments, the microphone is positioned at the equator 140 of the sonde 110, below the equator 140 of the sonde 110, or displaced laterally from the vertical axis 160 of the sonde 110. In these various embodiments, the size, length, position, etc. of the stalk 120 is provided in the rain sensor 100 as appropriate to position the microphone 130 accordingly.
- the microphone 130 comprises a circuit and has an electret design.
- the microphone is highly sensitive to acoustic signals in the range of from approximately 6 to approximately 10 kHz (e.g., approximately 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, or 10.0 kHz).
- the microphone 130 produces an analog voltage proportional to the acoustic power.
- the analog voltage is sampled at 32 kHz, 16-bits to produce a digital time varying signal. In some embodiments, the analog voltage is sample at 44.1 kHz. While the technology is described as comprising an electret microphone, the technology is not limited to an electret. microphone. Accordingly, the technology comprises, in some embodiments, a condenser microphone or other electromechanical components that convert an acoustic signal to an electrical output.
- the rain sensor further comprises a tube (e.g., having an outer diameter of approximately 38.1 mm and a wall thickness of approximately 1.24 mm).
- the tube extends downward (e.g., approximately 200 mm) from the sonde.
- the tube terminates in a plug.
- the stalk extends through the tube and into the sphere as described above.
- the tube is made from stainless steel; in some embodiments, the plug is made from aluminum.
- strain or force sensors e.g., load cells
- exemplary forces sensed by the instrument include, for example, static loads (e.g., wind) or dynamic loads (e.g., wind gusts, shock from hydrometeor (e.g., hail) impacts, etc.)
- the rain sensing apparatus is integrated into a weather-sensing device as described in U.S. Pat. Nos. 9,846,092 and 9,958,346, each of which is incorporated herein by reference in its entirety.
- the rain sensing apparatus described herein is integrated into a weather-sensing apparatus (e.g., as described in U.S. Pat. Nos. 9,846,092 and 9,958,346), the technology is not limited to such embodiments.
- the rain sensing apparatus comprises a sonde, stalk, and a microphone as described herein and does not necessarily comprise a drag- generating component, stalk or tube, strain sensors (e.g., load cells), and/or other components of the weather-sensing apparatus as described in U.S. Pat. Nos. 9,846,092 and 9,958,346.
- Figure 2 shows the impact location and impact angle of a raindrop 280 impacting the sonde normal to the sonde surface and the impact location and impact angle of a raindrop 281 impacting the sonde at an angle of impact Q 261.
- a vector 270 comprises the direction of motion of raindrop 280 at the moment of impact of raindrop 280 with the sonde.
- a vector 271 comprises the direction of motion of raindrop 281 at the moment of impact of raindrop 281 with the sonde. Intersections of vectors 270 and 271 with the sonde surface define the impact locations of raindrops 280 and 281, respectively.
- Axis 260 is normal to the sonde surface and passes through the location of impact of raindrop 280 and the sonde center 290.
- Axis 251 is normal to the sonde surface and passes through the location of impact of raindrop 281 and the sonde center 290.
- Raindrop 280 impacts the surface of the sonde normal to the sonde surface and therefore has an impact angle of 0° (zero degrees).
- Raindrop 281 impacts the surface of the sonde at an angle of impact Q 261.
- the angle of impact Q 261 is measured between the vector 271 comprising the direction of motion of raindrop 281 at the moment of impact of raindrop 281 and the axis 261 normal to the sonde surface at the impact site of raindrop 281.
- the same angle Q 260 is formed between the axis 251 normal to the sonde surface at the impact site of raindrop 281 and the vertical axis 260.
- the spherical shape appears the same in all directions relative to impacting rain and thus the treatment of the impact geometry with respect to the sonde surface is the same regardless of impact location.
- Droplets can strike the sonde at an angle 0 (e.g., 0 ⁇ 0 ⁇ 90°) relative to an axis normal to the sonde surface at the location of impact, e.g., from normal to the surface (0°) to a glancing impact (approaching 90°).
- Figure 3 shows measurements (similar to those in Figure 2) associated with the impacts of a raindrop 380 impacting the sonde at an angle of impact Q 360 and a raindrop 381 impacting the sonde normal to the sonde surface.
- a vector 370 comprises the direction of motion of raindrop 380 at the moment of impact of raindrop 380 with the sonde.
- a vector 371 comprises the direction of motion of raindrop 381 at the moment of impact, of raindrop 381 with the sonde. Intersections of vectors 370 and 371 with the sonde surface define the impact locations of raindrops 380 and 381, respectively.
- Axis 360 is normal to the sonde surface and passes through the location of impact of raindrop 380 and the sonde center 390.
- Axis 361 is normal to the sonde surface and passes through the location of impact of raindrop 381 and the sonde center 390.
- Raindrop 381 impacts the surface of the sonde normal to the sonde surface and therefore has an impact angle of 0° (zero degrees).
- Raindrop 380 impacts the surface of the sonde at an angle of impact Q 360.
- the angle of impact Q 360 is measured between the vector 370 comprising the direction of motion of raindrop 380 at the moment of impact of raindrop 380 and the axis 360 normal to the sonde surface at the impact site of raindrop 380.
- the impact location and impact angle of raindrops impacting the sonde affect the amount of impact energy transferred to the sonde and, consequently, affect the resulting acoustic signal detected by the microphone. Further, the impact energy transferred to the sonde is mediated by the hydrodynamics of the droplet and sometimes can be affected by water already existing (puddled) on the surface at that location. The impact energy mechanically shocks the sonde, which causes the sonde to vibrate and produce an acoustic vibration (ringing) inside the sonde volume.
- this frequency range is contemplated to be a natural frequency of the spherical sonde, which acts similarly to a bell.
- the microphone is highly sensitive to acoustic signals in the characteristic frequency range produced by the sonde due to rain impacts, e.g., from approximately 6 to approximately 10 kHz (e.g., approximately 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, or 10.0 kHz).
- the microphone produces an analog voltage proportional to the acoustic power.
- the analog voltage is sampled at 32 kHz, 16-bits to produce a digital time varying signal.
- the analog voltage is sample at 44.1 kHz.
- the digital time varying signal provides a datastream that is analyzed in real time.
- the datastream is analyzed by a component of the apparatus configured to compute statistical parameters that correspond to rain and characterize rain. Experiments conducted during the development of embodiments of the technology indicated that the sampling rate is chosen to extract useful information from the approximately 6-10 kHz carrier frequency, while minimizing the computational load and power consumption when analyzing the signal.
- the test droplets had a diameter of 2.419 ⁇ 0.089 mm (variation of 3.70%) and a mass of 7.41 ⁇ 0.82 mg (variation of 11.00%) .
- the rain droplets impacted the sonde at the same location on the sonde surface, which was the“north pole” of the sonde where the vertical axis intersects the sonde surface.
- the drops fell onto the sonde from a height of 1.2 m from the surface of the sonde.
- a microphone positioned inside the sonde was used to record the acoustic signal, which was continuously sampled at 32 kHz.
- the drops produced a train of sharp spikes with amplitude well above the
- the data indicated that the signal reduced gradually over approximately 100 milliseconds. Further analysis indicated that the data had a finer structure comprising an amplitude modulation (AM) of the primary ring frequency (Figure 4C). Analysis of the data indicated that the signal comprises a characteristic AM signature comprising components that correlate with various parameters of individual impacting drops such as droplet size and position of the droplet strike on the sonde surface.
- AM amplitude modulation
- the peak acoustic power is defined as the peak excursion of the acoustic power derived from the audio signal.
- the raw (AM) acoustic signal was transformed to provide a demodulated signal with positive values corresponding to the instantaneous amplitude of the primary ring oscillation.
- the peak acoustic power (I 1 -value) is the peak of this function.
- the P-value was 970 counts. Data collected during these experiments indicated that the peak did not typically occur at. the moment of the drop impact., which is what, would have been expected from an ideal damped oscillatory system. The difference is due to the microphone recording and/or acquiring the acoustic signal inside the sonde (e.g., air) volume and not the direct, mechanical vibrations of the sonde shell itself.
- embodiments of the rain measurement method comprise obtaining an acoustic signal from raindrop impacts on the sonde (e.g., obtained by a microphone), digitizing the acoustic signal, and processing the digitized acoustic signal.
- the raw 32 -kHz signal for a single drop is similar to a damped oscillation at the primary ring frequency specific to the sonde.
- the first data processing step is demodulating the amplitude modulated (AM) signal.
- the AM signal is a real-time digital signal; thus, the demodulation is continuously applied to discrete points ( Figure 7, black dots), e.g., using a running method.
- the algorithm looks forward in time, identifying peaks in the absolute value of signal intensity (e.g., absfyO). Intermediate points are estimated by interpolation between known peaks ( Figure 7, white dots), e.g., according to Equation l:
- Equation 1 the pu are the interpolated points determined by the analysis, yio is the previously identified peak at io, ya is the next identified peak at 12, and the current index is
- the second data processing step comprises use of an envelope (e.g.,“airplane”) function, e.g., applied as a running calculation on the real-time signal.
- an envelope e.g.,“airplane”
- a new series is generated from the previously demodulated signal, e.g., according to Equation 2.
- Equation 2 i is the previously calculated index and i + 1 is the new index to be calculated.
- the new series climbs over each rise, then glides past the peak, smoothing out subsequent structure on the back side of the peak.
- the climb and glide functions and fg can be of any form and adjusted independently.
- & was adjusted to allow a sharp climb to preserve the initial peak (P -value) and f g was an exponential form with a time constant on the order of approximately 1 to approximately 10 milliseconds (e.g., approximately 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.6, 3.6,
- the airplane filter is designed to preserve both the P-value and acoustic energy (Ea) of individual raindrop impacts.
- the fine (e.g., approximately 1-3 Hz) structure in the oscillation is preserved, which contains additional information about impact positions and water puddling.
- this fine structure is removed.
- a long glide function allows the sample to be downsampled to approximately 3.2 Hz (e.g., approximately 2.5 to 4.0 Hz (e.g.,
- the rain measurement system uses a microphone placed inside a spherical sonde in the top of the unit. Then, in some embodiments the microphone records the audio signal of raindrops striking the exterior of the sonde. Accordingly, each strike by a single droplet produces a characteristic pulse (see, e.g., Figures 4A, 413, and 4C). Then, in some embodiments, the real-time audio signal is preprocessed and downsampled to extract the envelope of the each pulse.
- rain rate measurement is based on a statistical correlation between parameters in this aggregate signal and rain rate.
- experiments were conducted to analyze single drop strikes and to evaluate microphone placement, within the apparatus.
- experiments were conducted using a train of single droplets that impacted the top of a sonde and the acoustic signal from drop impact was recorded with a microphone inside the device.
- acoustic signatures recorded by an embodiment of the technology provided herein were simulated for rain rates of 2 mm/hour ( Figure 11 A), 10 mm/hour ( Figure 11B), and 100 mm/hour ( Figure 11B). Although individual strikes were observable, they often overlapped and many small strikes were not. sufficiently resolved. Further, experiments conducted during the development of the technology provided herein indicated that the acoustic signature was dependent on both droplet size and strike position.
- data collected during the development of embodiments of the technology indicated that statistically averaged quantities associated with the real-time acoustic signal provide a measure of rain rate.
- the technology comprises applying statistical treatments to the time-varying acoustic power signal to obtain a measure of rain rate.
- the technology comprises determining statistical parameters from a distribution of the time -varying acoustic power signal (e.g., peak height, frequency in various frequency bands, mean amplitude, shape and length of the tail of the distribution, shape of the distribution, etc.)
- a method is used in which the yi values of the filtered acoustic power signal (P-Acoustic, e.g., as shown in Figure 11A and Figure 11B) are collected and analyzed (e.g., to extract statistical parameters providing a measure of rain rate).
- P-Acoustic e.g., as shown in Figure 11A and Figure 11B
- Data collected during the development of embodiments of the technology indicated that the distribution of yi values changed as a function of rain rate. In particular, the distribution broadened and moved toward higher P-Acoustic values as the rain rate increased.
- a method is used in which the filtered acoustic power signal (P-Acoustic, e.g., as shown in Figure 11A and Figure 11B) is analyzed using a peak-finding algorithm.
- this algorithm identifies individual peaks and their time of occurrence and amplitude (P -value).
- the peaks are appropriately corrected for superposition effects.
- the technology comprises applying statistical treatments to a distribution of peak attributes (e.g., peak height, time of occurrence) of the peaks in the peak dataset.
- peak data time of occurrence and amplitude
- rain measurement methods provided herein comprise applying a statistical analysis to the acoustic power signal recorded by a microphone inside the sonde.
- the signal is filtered and analyzed over fixed time intervals.
- a number of parameters is calculated from a distribution of raw acoustic power signal data or filtered acoustic power signal data, e.g., peak height, characteristic width, and/or frequency of occurrence within various bands. Over a sufficient measurement time, one can derive a blended acoustic parameter incorporating multiple characteristics of the acoustic power distribution that minimizes error per sampling period.
- experiments were conducted in which statistical parameters were calculated for rain rates recorded by an apparatus as described herein. Data collected during these experiments and subsequent data analysis indicated that the blended acoustic parameter and the P-value are correlated to rain rate. Accordingly, experiments were conducted during the development of embodiments of the technology provided herein to collect rain rate data and develop a correlation function for rain rate using the blended acoustic parameter and P- value. In addition, experiments were conducted during the development of embodiments of the technology provided herein to collect rain rate data and develop a correlation function for rain rate using the P-value distribution.
- acoustic signal derived parameters e.g., the acoustic parameter
- the co-located apparatus and disdrometer collected data during a rain event, with suitable precautions taken concerning spacing, wind effects, etc.
- the blended acoustic parameter calculated from data collected by the sonde over the time interval was plotted against the rain rate as measured by the disdrometer for the same time interval. Analysis of the data indicated that a power law function described the relationship between the blended acoustic parameter calculated according to the technology described herein and the disdrometer data.
- the technology provides a method to measure (e.g., estimate) the instantaneous rain rate directly from the microphone acoustic signal.
- experiments were conducted during the development of embodiments of the technology described herein in which the rain rate determined by a disdrometer for a rain event was compared to the instantaneous rain rate calculated for the same rain event using the acoustic signal from an apparatus as described herein and the power law parameters determined from the analysis described above ( Figure 12).
- the estimated rain rate calculated using the acoustic signal and the power law parameters matched the data recorded by the disdrometer ( Figure 12).
- an apparatus as described herein, e.g., comprising a sonde and a microphone placed inside the sonde. While, in some embodiments, individual rain droplet strikes and sizes are less resolved during rain events, embodiments comprise use of statistical methods and a correlation function to yield a useful quantitative measure of rain rate and rain accumulation.
- Droplet size distributions can vary significantly depending on the weather conditions from which rain emerges. For instance, observed droplet size distributions for different types of rain calculated at 10 mm/hour steady rate have a mean droplet diameter ranging from 0.5 to 1.6 mm. See, e.g., Ulbrich, (1983)“Natural variations in the analytical form of the raindrop size distribution” Journal of climate and Applied Meteorology 22' ⁇ 1764.
- the population of large droplets can vary widely.
- different rain types e.g., having a range of volume distributions from approximately 0 to approximately 1 cm 3 /m 3 /mm and a droplet diameter ranging from approximately slightly more than 0 (e.g., 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 mm) to 5 mm and, according to some observations, as large as approximately 6 mm
- a statistical parameter (and correlation function) that is minimally affected by these differences accurately estimates rainfall under all conditions and rain types.
- Example 8 Wind correction and calibration
- a correlation function based on the acoustic parameter accurately measures rain rates.
- the methods for measuring rain rate provide similar measures of rain rate as a disdrometer and tipping bucket standard.
- differences in the acoustic responses of different sondes and/or different microphones may exist between different rain-sensing apparatus units. Without being bound by any particular theory, it is contemplated that variability can be due to many things, including mechanical and structural aspects of the sonde (which acts similar to a bell) and electronic characteristics of the circuit components. Improved design and manufacturing techniques can reduce this variability, but. it is likely that some sensitivity differences will remain in these
- Calibrating individual apparatuses to a standard is considered impractical, e.g., because collecting real rain data in a large volume manufacturing environment is not efficient and it is difficult to generate acoustic inputs or develop indoor“rain” chambers that closely match real rain. For this reason, in some embodiments the technology provides an apparatus as described herein that performs self-calibration, e.g., when deployed for measurement at the measurement site.
- an apparatus as described herein is calibrated against standards to yield a correlation function that accurately predicts rain.
- a real-time and/or post-processing numerical (or analytical) transformation converts the raw datastream to a datastream that measures the rain rate more accurately.
- the technology comprises correcting drop characteristics (e.g., drop velocity, momentum, size, volume, etc.) due to wind.
- the rain sensing apparatus is integrated into a weather- sensing device as described in U.S. Pat. Nos. 9,846,092 and 9,958,346, each of which is incorporated herein in its entirety.
- the weather-sensing apparatus measures wind velocity (e.g., speed and direction) and detects individual hydrometeors (e.g., hail).
- the acoustic energy (e.g., the sum of the absolute value of the sound recorded by the transducer) of rain is approximated as a linear response with respect to the rain volume impacting the rain detector described herein.
- the distribution of drop sizes and the distribution of drop speeds produced by a rain event do not vary substantially among rain events. That is, rain events produce rain having a distribution of drop sizes and a distribution of drop speeds that does not vary substantially from rain event to rain event.
- the volume of rain e.g., the aggregate drops impacting the rain detector in a period of time
- the volume of rain generally produces a fixed acoustic signal on a specific rain-detecting device.
- the acoustic signal in corrected for wind speed.
- Rain generally falls vertically in the absence of wind.
- the presence of wind adds a horizontal component to the rain velocity and in some instances increase the total velocity of rain drops in a volume of rain.
- the wind -increased velocity of rain drops can produce an artificially increased acoustic power detected by the rain detector for a given volume of rain (e.g. Figure 16).
- correcting the acoustic power and/or rain rate and/or rain volume for wind improves the correlation of the measured signal (e.g., acoustic power or acoustic energy) with rain rate and/or rain volume.
- correcting the rain rate and/or rain volume for wind provides an acoustic power that is a proxy that is proportional to the rain rate and/or rain volume but that is also specific to the particular rain detecting device used to measure rain (e.g., due to nuances in the construction of each device).
- embodiments provide methods for determining a calibration point for a rain sensing device so that, the acoustic power measured by the rain sensing device correlates to the rain rate regardless of the individual device.
- Raindrops are produced in a variety of sizes when water vapor condenses in the atmosphere.
- rain drops are generally between approximately 0.5 and 4.0 or 5.0 mm in diameter (e.g., a diameter of approximately 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 mm) at ground level even though raindrops outside of this range can be formed higher in the atmosphere.
- the maximum drop size reaches approximately 4.0 or 5.0 mm in diameter and, as discussed above, the maximum drop size does not increase past
- the acoustic power at this plateau point is used as a normalization constant to transform acoustic power readings from an individual rain detector to the equivalent number of time intervals of known rain rate.
- the plateau point described above lies at a sum of approximately 10 7 ⁇ 25 and represents a rain rate of approximately 30 mm per hour.
- the acoustic power values are divided by the normalization constant to provide a number of equivalent time intervals of the known rain rate (see, e.g., Figure 18A and Figure 18B).
- the plots in Figures 18A and Figure 18B show the rainfall detected during multiple different storms using one particular rain detector (84ebl8eb2a8b) as a function of the number of 10-second intervals of this rainfall rate that the acoustic power represents without wind correction (Figure 18A) and with wind correction (Figure 18B).
- the data in Figure 18A and Figure 18B are plotted against the rain measured by a tipping bucket rain measuring device.
- methods comprise calculating a real rainfall rate from the number of equivalent time intervals of the fixed rain rate.
- Data were collected from multiple rain detection devices (e.g., six different devices) during the development of the technology provided herein. Rain rates were determined for each device according to the methods described above and the data plotted against data collected by a co -located tipping bucket ( Figure 19).
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- 2019-11-05 CN CN201980087877.XA patent/CN113366344A/en active Pending
- 2019-11-05 SG SG11202104490PA patent/SG11202104490PA/en unknown
- 2019-11-05 CA CA3118143A patent/CA3118143A1/en active Pending
- 2019-11-05 EP EP19881099.6A patent/EP3887874A4/en not_active Withdrawn
- 2019-11-05 US US17/289,054 patent/US20210405254A1/en not_active Abandoned
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- 2019-11-05 AU AU2019375967A patent/AU2019375967A1/en active Pending
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US20210405254A1 (en) | 2021-12-30 |
EP3887874A4 (en) | 2022-10-26 |
AU2019375967A1 (en) | 2021-06-03 |
CN113366344A (en) | 2021-09-07 |
CA3118143A1 (en) | 2020-05-14 |
IL282733A (en) | 2021-06-30 |
US20200142099A1 (en) | 2020-05-07 |
SG11202104490PA (en) | 2021-05-28 |
EP3887874A1 (en) | 2021-10-06 |
KR20210096124A (en) | 2021-08-04 |
JP2022516219A (en) | 2022-02-25 |
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