CN115184638A - Deep sea LADCP observation data post-processing method and processing terminal - Google Patents
Deep sea LADCP observation data post-processing method and processing terminal Download PDFInfo
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Abstract
The invention discloses a deep sea LADCP observation data post-processing method and a processing terminal, wherein the method comprises the following steps: step 1: obtaining LADCP original observation data; step 2: dividing a plurality of layers according to the inclination angle change rate and the depth, wherein the larger the inclination angle change rate is, the smaller the layer thickness is and the more the layer number is; and step 3: calculating the average flow velocity of each layer according to the flow velocity profile covered by the current layer; and 4, step 4: respectively calculating the flow rate shear and a relative flow rate profile of each layer, wherein the relative flow rate profile is obtained by superposing the flow rate shear on the flow rate average value; and 5: and calculating an absolute flow velocity profile, wherein the absolute flow velocity profile is obtained by superposing a reference flow velocity on a relative flow velocity profile. The invention adopts a layered average thought, can process and obtain the seawater absolute flow velocity and flow velocity shear with high precision and high accuracy from the LADCP data of the low-echo deep sea environment, and is superior to the currently commonly used inverse method and shear method.
Description
Technical Field
The invention relates to the technical field of LADCP data processing, in particular to a deep-sea LADCP observation data post-processing method and a processing terminal.
Background
Compared with the ADCP observation mode, the observation data obtained by the LADCP observation belongs to 'shingled data', in the process of putting and recovering the LADCP, sound waves transmitted each time can obtain a corresponding flow velocity profile, and the flow velocity profile a obtained by the currently transmitted sound waves and the flow velocity profile b obtained by the last transmitted sound waves are overlapped in depth, namely at least one part of the flow velocity profile a and the flow velocity profile b cover the same depth. At present, the LADCP data processing method in the international oceanic community mainly comprises two methods, namely a shearing method and an inverse method. In actual ocean current observation, the quality of each layer of flow velocity data calculated by using a shearing method is theoretically not influenced mutually, and the reflected ocean current condition is relatively real; however, the superposition algorithm of the shearing values can lead the error to be accumulated, and the finally calculated absolute flow velocity of the upper layer or the bottom layer of the ocean is greatly different from the true value. The inverse method has the advantages that additional information, such as high-precision GPS data and shipborne ADCP data, is fully utilized, so that the obtained flow velocity profile approaches to a real flow field to a greater extent; however, since the principle is to consider the entire flow velocity profile as an integral function, too much invalid observation data acquired in deep sea with low echo intensity may cause the flow velocity profile to be calculated unsuccessfully. In addition, the accuracy of the flow shear calculated by the inverse method is slightly lower than the calculation result of the shear method, which is disadvantageous for the calculation of the marine mixing ratio depending on the flow shear. Therefore, it is necessary to develop a post-processing method and a processing terminal for processing the deep sea laccp data in the low echo environment to obtain high-precision absolute flow rate and flow rate shear of the sea water.
Disclosure of Invention
In view of the deficiencies of the prior art, it is an object of the present invention to provide a method for post-processing observed data of a deep-sea LADCP, which can solve the problems described in the background art;
it is another object of the present invention to provide a processing terminal that can solve the problems described in the background.
The technical scheme for realizing one purpose of the invention is as follows: a deep sea LADCP observation data post-processing method comprises the following steps:
step 1: obtaining LADCP original observation data;
step 2: splicing the flow velocity profiles in the original LADCP observation data together according to the depth to obtain the depth-inclination angle change profile data of the inclination angle change rate of the LADCP measuring instrument along with the depth,
sequentially dividing the depth-dip angle change profile data into N layers according to the depth, wherein any two layers are not overlapped in depth, N is more than or equal to 2, and the thickness of the k layer is B k ，k＝1,2,…,N；
And step 3: the average flow rate for each layer was calculated according to equation (1):
in the formula (I), the compound is shown in the specification,
represents the flow rate average, U, of the k-th layer ik Represents the flow rate of the k layer corresponding to the i-th release signal, n k Representing the number of flow velocity profiles covered by the kth layer;
and 4, step 4: calculating the flow shear S of the kth layer according to the formula (2) k And (3) calculating the relative flow velocity profile of each layer according to the formula:
in the formula of U bc,k Represents the relative flow velocity profile of the k-th layer, b k Representing the thickness of a water layer between any two adjacent observed values on the same flow velocity section where the kth layer is located;
and 5: the absolute flow profile is calculated according to equation (4):
U abc,k ＝U bc,k +U ref ------④
in the formula of U abc,k Represents the absolute flow velocity profile, U, of the k-th layer ref Indicating a reference flow rate.
Further, in the step 2, the larger the inclination angle change rate is, the smaller the divided layer thickness is and the larger the number of layers is.
Further, the divided layer thicknesses satisfy the following relationship:
in the formula, Z ik Indicating the depth of the k-th layer corresponding to the i-th release acoustic signal.
Further, in the step 4, a balancing process is further included:
the flow velocity value on the relative flow velocity profile of the middle position a on the depth of the layer above the current layer at the position of the flow velocity shear mutation is U a The flow velocity value of the middle position b on the depth of the next layer is U b ，
If U is a ＞U b The smoothed flow velocity between the position a to the position b in the depth increasing directionThe shear value is calculated as follows:
wherein (n + 1) represents the total number of shear values between position a and position b excluding the two end positions (a, b), S m Denotes the m-th smoothed flow shear value, U, counted from the next flow value starting at position a m Representing the mth flow velocity value counted from the next flow velocity value starting at position a,
if U is a ＜U b Then the smoothed flow shear value between position a to position b in the depth increasing direction is calculated as follows:
the flow rate shear value S obtained by the smoothing treatment of the formula m Substitution of S m The flow shear of the layer is calculated according to the formula (2).
Further, after the absolute flow velocity profile is obtained through calculation in step 5, the method further includes performing optimization processing on the absolute flow velocity profile, where the optimization processing includes one or more of the following schemes one to four:
the first scheme is as follows: calculating the depth of the LADCP at the same moment by using CTD depth data, calibrating the time of the maximum vertical integral of the flow rate w of the LADCP and the time of the CTD at the deepest position, and interpolating the depth obtained by the CTD to the time recorded by the LADCP so as to enable the depth and the flow rate to be in one-to-one correspondence;
scheme II: after the quality control is carried out on the GPS positioning data, the reference flow rate is calculated in a segmented mode, and then the reference flow rate of each segment is superposed on an LADCP observation system in the same time period, so that the optimization of the reference flow rate is realized;
the third scheme is as follows: taking an interval from a certain water depth to a position above the seabed as a low-echo-intensity water layer, and if the number of effective data obtained by one-time observation of the water layer above the low-echo-intensity water layer in the transducer is less than 2, excluding the observation; if the effective data of the low echo intensity water layer is less than 1, excluding the observation;
if the effective data of the echo intensity water layers is 1, dividing a plurality of water layers for the low echo intensity water layers, calculating the average value of all flow rates in each water layer, and adding the relative flow rate calculated by the GPS at the same moment to each observed flow rate to replace the flow rate of the water layer;
and the scheme is as follows: through the influence of vertical filtering's mode greatly reduced hawser traction force to the velocity of flow observation, specifically include:
firstly, the average value of the flow velocity data of the 2 nd to 5 th layers obtained by each echo of the LADCP is taken, the average value is arranged from the sea surface to the sea bottom, and a flow velocity signal with a stable period at each section is filtered by using a sectional vertical filtering method.
Further, the flow rate data is band-pass filtered using a butterworth analog filter of order 3.
The second technical scheme for realizing the aim of the invention is as follows: a processing terminal, comprising:
a memory for storing program instructions;
and the processor is used for operating the program instructions to execute the steps of the deep sea LADCP observation data post-processing method.
The invention has the beneficial effects that: compared with the traditional method, the invention adopts a layered average thought, and the calculation result improves the precision and accuracy of the absolute flow velocity and flow velocity shearing of seawater at each layer under the low-echo deep sea environment, and is superior to the currently commonly used inverse method and shearing method.
Drawings
FIG. 1 is a schematic flow diagram of the present invention;
FIG. 2 is a schematic diagram of raw observation data of LADCP;
FIG. 3 is a schematic diagram of depth-tilt profile data;
FIG. 4 is a schematic comparison of depth-flow shear smoothing before and after treatment;
FIG. 5 is a schematic diagram showing a comparison of two modes of depth acquisition using vertical flow rate integration and CTD depth data;
FIG. 6 is a schematic cross-sectional view of the flow rate obtained using the optimization of the present invention and conventional GPS processing;
FIG. 7 is a schematic view of the flow velocity profile of a low echo intensity water layer obtained by the optimization of the present invention;
fig. 8 is a schematic diagram of the structure of the processing terminal.
Detailed description of the preferred embodiments
The invention will be further described with reference to the accompanying drawings and specific embodiments:
as shown in fig. 1 to 7, a method for post-processing observed data of a deep-sea LADCP includes the following steps:
step 1: raw observed data of LADCP were obtained.
Referring to fig. 2, the raw observed data of the LADCP belongs to "shingled data", and the raw observed data of the LADCP includes a plurality of flow velocity profiles, and two adjacent flow velocity profiles may partially overlap in depth. The dots on the straight line segment in fig. 2 represent the release once acoustic signal, and the curved line segment represents the flow velocity profile corresponding to the release once acoustic signal, and it can be seen from the figure that there is a deep overlap between the two flow velocity profiles obtained by two adjacent release once acoustic signals.
And 2, step: and acquiring depth-dip angle change profile data of the dip angle change rate of an LADCP measuring instrument (acoustic Doppler current profiler) along with the depth from the LADCP original observation data. During the lowering or retrieving process of the lacp measuring instrument, the lacp measuring instrument can record the inclination angle of the lacp measuring instrument, and the inclination angle change rate is the derivative of the inclination angle with respect to the depth, for example, the recorded inclination angle is represented by tilt, and the depth is represented by z, so the inclination angle change rate is d (tilt)/dz.
Sequentially dividing the depth-dip angle change profile data into N layers according to the depth, wherein any two layers are not overlapped in depth, N is more than or equal to 2, and the thickness of the k layer is B k ，k＝1,2,…,N。
In an alternative embodiment, the greater the inclination angle rate, the smaller the layer thickness and the greater the number of layers, i.e. the smaller the depth, to be subdivided. Suspended particles in the sea water of the offshore surface layer, as seen from the direction of increasing depth of the surface and the seabedMore, large echo intensity, rich effective data and high data reliability, but due to large flow velocity and strong shear, the LADCP measuring instrument is extremely unstable (the change of the inclination angle along with the depth is large) in the up (recovery) and down (lowering) moving process, so that the layer thickness B can be properly reduced k (ii) a The flow velocity and the shear in the deep sea area are reduced, the moving process of the LADCP is stable, but the B can be properly increased due to the fact that the scattering intensity is small, the echo intensity is small, and effective data are reduced k 。
Referring to fig. 3, fig. 3 is a schematic view of depth-tilt profile data, in which the abscissa represents a tilt rate and the ordinate represents a depth in m (meters). In the figure, the inclination angle change rate is large at the offshore surface (about 2m-16m depth), near the depth 75m, and near the depth 150m, and therefore, the layer thickness to be divided is smaller in these depth regions, that is, the covering depth is smaller. In this embodiment, the depth-dip angle change profile data reflected in fig. 3 is divided into N =12 layers, the total depth is 200m, wherein B is the depth increase direction from the sea surface and the sea bottom 1 ＝B 2 ＝10m，B 3 ＝40m，B 4 ＝B 5 ＝B 6 ＝10m，B 7 ＝30m，B 8 ＝B 9 ＝B 10 ＝B 11 ＝10m，B 12 =40m. It can be seen that two layers are divided on the offshore surface, three layers are divided near the depth of 75m, four layers are divided near the depth of 150m, and the layer thicknesses of the layers are all 10m and are smaller than those of other regions.
And 3, step 3: the flow rate average for each layer is calculated according to equation (1):
in the formula (I), the compound is shown in the specification,
denotes the flow rate average, U, of the k-th layer i,j Representing the flow rate of the j-th layer corresponding to the i-th release signal, whose value is directly recorded by LADCP, n k Indicating coverage of the k-th layerNumber of flow velocity profiles. For example, as B of FIG. 3 3 Layer as an example, B 3 The layers are divided after splicing the original individual flow velocity profiles, before splicing, if B 3 The layer covers 3 flow velocity profiles, namely 3 flow velocity profiles cover the area with the depth of 20m-60m, and n is k And =3. Therefore, the thickness of the divided layers is different, which affects n k The value further influences the flow velocity average value, so that the purpose of more accurately calculating the flow velocity average value can be achieved by adjusting the layer thickness.
And 4, step 4: the flow velocity of the jth water layer of the section obtained by the ith infrasonic wave emission is U i,j B is the distance between 2 adjacent observed values on the same section, and the flow rate shear S in the section is calculated according to the formula (2) i,j And (4) calculating the relative flow velocity profile of each layer according to the formula (3):
in the formula of U bc,k The relative flow velocity profile of the kth layer is shown, and b shows the thickness of the water layer between any two adjacent observed values on the same flow velocity profile of the kth layer.
In this step, the flow rate shear between adjacent layers may have a large abrupt change from the actual flow rate shear due to the splicing in step 2, and in addition, the layer thickness of each layer cannot be too small to continue the subdivision, so that it is necessary to smooth the flow rate shear. The smoothing process includes the steps of:
the flow velocity value on the relative flow velocity profile of the middle position a on the depth of the layer above the current layer at the position of the flow velocity shear mutation is U a The flow velocity value of the middle position b on the depth of the next layer is U b 。
If U is a ＞U b A plane between a position a to a position b in the depth increasing directionThe flow shear value after slip is calculated as follows:
in the formula, (n + 1) represents the total number of shear values between the position a and the position b excluding the two end positions (a, b), that is, n +1 shear values in the depth interval, and S m Denotes the m-th smoothed flow shear value, U, counted from the next flow value starting from position a m Indicating the mth flow velocity value counted from the next flow velocity value starting at position a.
If U is a ＜U b Then the smoothed flow shear value between position a to position b in the depth increasing direction is calculated as follows:
the flow rate shear value S obtained by the smoothing treatment of the formula m Substitution of S m The flow shear of the layer is calculated according to the formula (2).
Referring to fig. 4, the left half of fig. 4 is a schematic diagram of depth-flow rate shear without smoothing, and the position of the dashed oval frame in the diagram is that sudden change abnormality occurs in flow rate shear, and the right half of fig. 4 is shown after smoothing according to the present invention. From this comparison, the present invention considers both the absolute value of the flow rate and the accuracy of the flow rate shear value.
And 5: the absolute flow profile is calculated according to equation (4):
U abc,k ＝U bc,k +U ref ------④
in the formula of U abc,k Represents the absolute flow velocity profile, U, of the k-th layer ref The reference velocity is obtained by bottom tracking or GPS data, which belongs to the prior art and is not described herein, and the reference velocity records the error of the original LADCP observation data caused by the position change of the detection ship in the whole observation process, so that the reference velocity can be obtained by bottom tracking or GPS data, therebyThe splicing flow velocity is adjusted to obtain a more accurate absolute flow velocity profile.
In an optional embodiment, after the absolute flow velocity profile is calculated in step 5, an optimization process is further performed on the absolute flow velocity profile. The optimization processing of the absolute flow velocity profile comprises the following aspects:
on the first hand, there are usually 2 methods for estimating the depth of the LADCP, one is by integrating the vertical flow velocity w, and the other is by using the CTD to observe the depth in real time. However, after integrating the vertical flow velocity w in a large amount of original observation data of the laccp, it is found that the laccp is difficult to maintain a good constant velocity process due to the ocean current effect when being lowered, and a large amount of observation data is lost due to the reduction of scatterers in a deeper water layer, and the method 1 inevitably causes an error in the depth during the flow velocity inversion. The method adopted by the invention for optimizing the depth is to calculate the depth of the LADCP at the same time from the CTD depth calculated by the seawater toolkit. Because the time of the CTD and the LADCP is asynchronous, the CTD may have the problem of data loss and the like, the time of the maximum value of the vertical integral of the flow rate w of the LADCP and the time of the CTD positioned at the deepest part are calibrated, and then the depth obtained by the CTD is interpolated to the time recorded by the LADCP, so that the depth and the flow rate can be in one-to-one correspondence. Referring to fig. 5, comparing the vertical integration result of the flow velocity w and the CTD observation depth, it can be seen that the flow velocity w is not integrated to the maximum depth, data is more lost in the deeper water layer, and finally the integration is shifted to approximately 800m from the sea table. The lowering and recovery process of LADCP is well restored according to the pressure data recorded by the CTD.
In a second aspect, the determination of the reference flow rate requires additional information to be used with the LADCP observation system, such as bottom tracking information or GPS information. The principle of determining the reference flow rate by the bottom tracking method is that the near-bottom flow rate is regarded as the moving speed of the seabed relative to the LADCP instrument; the currently widely used method of GPS is to determine the reference flow rate based on the distance between the LADCP entering and exiting the water divided by the observation time. However, in practice, the movement of the observation vessel over the sea surface is not linear and uniform.
In view of the above, the present invention optimizes the reference flow rate by calculating the reference flow rate in segments after performing quality control on the GPS positioning data, and then superimposing the reference flow rate of each segment on the LADCP observation system in the same time period. Referring to fig. 6, fig. 6 compares with the conventional GPS positioning information, and it can be seen that better flow velocity profile can be obtained by using segmented and quality-controlled GPS positioning data, and the overall trend of the 2 methods is similar, but there is a large difference above 1300m, which is probably caused by a large error when observing the non-linear movement of the ship.
In a third aspect, in some deeper sea areas, the LADCP meter transducer can only receive 1 echo signal in a single observation, while at least 2 echo signals are required to calculate the flow shear. This results in less effective data for calculating the flow velocity profile, sometimes even data close to 1/2 being unusable. In a deeper water layer, the flow velocity of the seawater is small, the shearing is weak, the flow velocity of the water layer with low echo intensity can be inverted by a data processing method different from that of the upper layer seawater, and the use efficiency of data is improved.
Assuming that the water depth is 1000m or below and the water layer with low echo intensity is in a certain range above the bottom layer (namely the sea bottom), firstly, judging the number of effective data obtained by one-time observation of the water layer with more than 1000m on a transducer one by one, and if the number of the effective data is less than 2, excluding the observation; and when the effective data of the water layer below 1000m is less than 1, the effective data is eliminated, namely the observation is also eliminated. Most of 'low echo intensity water layers' only have 1 effective echo data, the 'low echo intensity water layers' can be divided into a plurality of water layers Dk according to a certain method, the average value of all flow rates in each Dk is calculated, and then the relative flow rate obtained by the GPS calculation at the same moment is added to each observed flow rate, so that the flow rate of the water layer is replaced, and the use efficiency of the LADCP data is greatly improved.
Referring to fig. 7, in fig. 7, for example, if at least 2 effective data are obtained by one time of LADCP measurement, the observation data below 2700m cannot be used; after the improved method is used, the depth of the flow velocity can be inverted to exceed 5000m at most, and the obtained deep seawater flow velocity is consistent with the actual flow velocity, which indicates that the method is favorable to a certain extent (the number of effective observation data at the fracture part is 0).
In a fourth aspect, the observation error caused by cable drag is most difficult to eliminate when using LADCP to observe the flow profile of seawater. If only the forces from the cables, the gravity and buoyancy of the instrument itself are considered, there will be a periodic back and forth oscillation of the lacpb, resulting in the periodic flow rate signal also being included in the observed flow rate. The periodic signal will be hidden in the actual ocean current flow rate and the vessel drift velocity. After the ship position is corrected by using the ship-borne GPS, the influence of the traction force of the mooring rope on the flow velocity observation can be further greatly reduced in a vertical filtering mode.
Firstly, the average value of the flow rate data of 2 th to 5 th layers obtained by each echo of the LADCP is taken, and the average value is arranged from the sea surface to the sea bottom. Assuming that the period of the reciprocating oscillation of the LADCP under the influence of the traction of the cable is between 3s and 40s and considering that the period of the oscillation of the LADCP increases slowly when the LADCP is lowered, a piecewise vertical filtering method is used to filter out the flow rate signal with a stable period for each segment. In the filter design, the invention uses a Butterworth analog filter of 3 orders to perform band-pass filtering on the flow rate data. The lower graph is a comparison of the flow rate profile before and after filtering measured by a certain LADCP. Referring to fig. 7, in the left half of fig. 7, although the shear shapes of the flow velocity profiles observed in the up-and-down process are similar, the absolute values of the flow velocities are greatly different, and the maximum value is more than 0.2m/s. On the right half of fig. 7, it can be seen that the flow velocity profile measured during lowering and recovery is more closely matched after vertical filtering. The duration of the observation is about 4 hours, and the flow velocity generally does not change greatly in the period, so that the accuracy of the flow velocity data can be effectively improved by the vertical filtering method.
The above four aspects can be performed together or one aspect can be selected to perform, that is, all the above four aspects can be optimized, or one or a combination selected from the above four aspects can be selected to perform optimization.
As shown in fig. 8, the present invention also provides a processing terminal 100, which includes:
a memory 101 for storing program instructions;
a processor 102 for executing the program instructions to perform the steps of the deep sea LADCP observation data post-processing method.
The embodiments disclosed in this description are only an exemplification of the single-sided characteristics of the invention, and the scope of protection of the invention is not limited to these embodiments, and any other functionally equivalent embodiments fall within the scope of protection of the invention. Various other changes and modifications to the above-described embodiments and concepts will become apparent to those skilled in the art from the above description, and all such changes and modifications are intended to be included within the scope of the present invention as defined in the appended claims.
Claims (7)
1. A deep sea LADCP observation data post-processing method is characterized by comprising the following steps:
step 1: obtaining LADCP original observation data;
step 2: splicing all flow velocity profiles in the original LADCP observation data together according to depth to obtain depth-dip angle change profile data of the dip angle change rate of the LADCP measuring instrument along with the depth,
sequentially dividing the depth-dip angle change profile data into N layers according to the depth, wherein any two layers are not overlapped in depth, N is more than or equal to 2, and the thickness of the kth layer is B k ，k＝1,2,…,N；
And step 3: the average flow rate for each layer was calculated according to equation (1):
in the formula (I), the compound is shown in the specification,
represents the flow rate average, U, of the k-th layer i,j Flow rate, n, of the j-th layer of the cross section obtained by the i-th release signal k Representing the number of flow velocity profiles covered by the kth layer;
and 4, step 4: calculating the k layer according to the formula (2)Shear of flow rate S k Calculating the flow shear S of the relative flow profile of each layer according to the formula (3) i,j :
In the formula of U bc,k B represents the thickness of a water layer between any two adjacent observed values on the same flow velocity section where the kth layer is located;
and 5: the absolute flow profile is calculated according to equation (4):
U abc,k ＝U bc,k +U ref ------④
in the formula of U abc,k Represents the absolute flow velocity profile, U, of the k-th layer ref Indicating a reference flow rate.
2. The method of claim 1, wherein in step 2, the larger the change rate of the inclination angle, the smaller the layer thickness and the larger the number of layers.
3. The method of claim 1, wherein the divided layer thicknesses satisfy the following relationship:
in the formula, Z ik Indicating the depth of the k-th layer corresponding to the i-th release acoustic signal.
4. The method of claim 1, further comprising a balancing process in step 4:
the flow velocity value on the relative flow velocity profile of the middle position a on the depth of the layer above the current layer at the position of the flow velocity shear mutation is U a The flow velocity value of the middle position b on the depth of the next layer is U b ，
If U is a ＞U b Then the smoothed flow shear value between position a to position b in the depth increasing direction is calculated as follows:
wherein (n + 1) represents the total number of shear values between position a and position b excluding the two end positions (a, b), S m Denotes the m-th smoothed flow shear value, U, counted from the next flow value starting at position a m Representing the mth flow velocity value counted from the next flow velocity value starting at position a,
if U is a ＜U b Then the smoothed flow shear value between position a to position b in the depth increasing direction is calculated as follows:
the flow rate shear value S obtained by the smoothing treatment of the formula m Substitution of S m The flow shear of the layer is calculated according to the formula (2).
5. The method of claim 1, wherein after the absolute flow velocity profile is calculated in step 5, the method further comprises performing an optimization process on the absolute flow velocity profile, wherein the optimization process includes one or more of the following first to fourth schemes:
the first scheme is as follows: calculating the depth of the LADCP at the same moment by using CTD depth data, calibrating the time of the flow rate w vertical integral maximum value of the LADCP with the time of the CTD at the deepest position, and interpolating the depth obtained by the CTD to the time recorded by the LADCP, so that the depth and the flow rate can be in one-to-one correspondence;
scheme II: after the quality control is carried out on the GPS positioning data, the reference flow rate is calculated in a segmented mode, and then the reference flow rate of each segment is superposed on an LADCP observation system in the same time period, so that the optimization of the reference flow rate is realized;
the third scheme is as follows: taking a deep water interval from a certain water depth to a depth above the sea bottom as a low-echo-intensity water layer, and if the number of effective data obtained by one-time observation of the water layer above the low-echo-intensity water layer on the transducer is less than 2, excluding the observation; if the effective data of the low echo intensity water layer is less than 1, excluding the observation;
if the effective data of the echo intensity water layers is 1, dividing a plurality of water layers for the low echo intensity water layers, calculating the average value of all flow rates in each water layer, and adding the relative flow rate calculated by the GPS at the same moment to each observed flow rate to replace the flow rate of the water layer;
and the scheme is as follows: through the influence of vertical filtering's mode greatly reduced hawser traction force to the velocity of flow observation, specifically include:
firstly, the average value of the flow velocity data of the 2 nd to 5 th layers obtained by each echo of the LADCP is taken, the average value is arranged from the sea surface to the sea bottom, and a flow velocity signal with a stable period at each section is filtered by using a sectional vertical filtering method.
6. The method of claim 5, wherein a Butterworth analog filter of order 3 is used to band-pass filter the flow data.
7. A processing terminal, characterized in that it comprises:
a memory for storing program instructions;
a processor for executing the program instructions to perform the steps of the method of post-processing of deep-sea LADCP observation data according to any of claims 1 to 6.
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