CN114355357A - Self-adaptive spectrum polarization filtering method and device of dual-polarized weather radar - Google Patents

Self-adaptive spectrum polarization filtering method and device of dual-polarized weather radar Download PDF

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CN114355357A
CN114355357A CN202210017954.8A CN202210017954A CN114355357A CN 114355357 A CN114355357 A CN 114355357A CN 202210017954 A CN202210017954 A CN 202210017954A CN 114355357 A CN114355357 A CN 114355357A
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filtering
rainfall
spectral polarization
spectral
polarization
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殷加鹏
安孟昀
黄建开
李健兵
庞晨
李永祯
王雪松
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National University of Defense Technology
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Abstract

The invention discloses a self-adaptive spectrum polarization filtering method and a self-adaptive spectrum polarization filtering device for a dual-polarization meteorological radar, wherein the method comprises the steps of determining a filtering threshold value of spectrum polarization filtering by using JS divergence according to the difference of the statistical characteristics of spectrum polarization parameters of a rainfall target and a non-rainfall target; obtaining a range-Doppler image of a spectral polarization parameter of original radar recovery data, and filtering the spectral polarization parameter by using the filtering threshold value to obtain a range-Doppler binary mask image; and performing clutter filtering and rainfall target identification based on the range-Doppler binary mask image. The invention can correct the filtering threshold of the spectral polarization filtering, and adaptively select the filtering threshold according to the rainfall conditions in different directions. The method has better clutter suppression and rainfall retention performance.

Description

Self-adaptive spectrum polarization filtering method and device of dual-polarized weather radar
Technical Field
The invention relates to the technical field of radar signal processing, in particular to a self-adaptive spectrum polarization filtering method and device of a dual-polarization meteorological radar.
Background
The meteorological radar can realize the observation of atmosphere high space-time resolution, is the essential instrument of atmosphere observation. However, because the working environment of the radar is complex, radar data is often affected by clutter, such as ground clutter, sea clutter, bio-echo, and the like. The clutter can seriously affect the measurement and estimation of the reflectivity, Doppler velocity and polarization parameters of meteorological targets, and further affect the atmospheric micro-physics research and rainfall estimation.
Scholars at home and abroad propose various clutter suppression methods to solve the clutter interference problem of the meteorological radar. For example, j.yin et al propose a Moving spectral Depolarization Ratio (MsDR) filter, which uses a spectral polarization filtering technique to solve the clutter suppression problem of dual-polarization radar without cross polarization measurement capability.
The spectral polarization filtering technique utilizes the difference of the spectral polarization characteristics of rainfall targets and non-rainfall targets on the RD (Range Doppler, abbreviated as RD) graph to filter non-rainfall targets while preserving as much rainfall targets as possible. The spectral polarization filtering technology determines a filtering threshold value according to the relation between the signal-to-noise ratio and corresponding filtering parameters and the removal proportion of the clutter and the rainfall, and generates a binary filtering value of {0,1} on the RD diagram by utilizing the threshold value, so as to act on the original power spectrum and realize the retention of the rainfall target and the filtering of the clutter. However, in an actual PPI (Plan Position Indicator, abbreviated PPI) scan, there is a difference in rainfall conditions in different azimuth directions, and clutter and noise depend on the geographical environment of the azimuth direction.
Therefore, in consideration of the difference of rainfall conditions in different directions, a new spectral polarization technique filtering method is proposed to obtain a better filtering effect and rainfall estimation, which is a technical problem that needs to be solved by those skilled in the art.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a self-adaptive spectrum polarization filtering method and device for a dual-polarization meteorological radar. The invention can carry out filtering according to rainfall conditions in different directions, thereby improving the filtering effect.
In order to achieve the technical purpose, the technical scheme provided by the invention is as follows:
in one aspect, the invention provides a self-adaptive spectrum polarization filtering method for a dual-polarization meteorological radar, which comprises the following steps:
determining a filtering threshold value of spectral polarization filtering by using JS divergence according to the difference of the spectral polarization parameters of a rainfall target and a non-rainfall target in statistical characteristics;
obtaining a range-Doppler image of a spectral polarization parameter of original radar recovery data, and filtering the spectral polarization parameter by using the filtering threshold value to obtain a range-Doppler binary mask image;
and performing clutter filtering and rainfall target identification based on the range-Doppler binary mask image.
In another aspect, the present invention provides an adaptive spectrum polarization filtering apparatus for dual-polarized weather radar, comprising:
the first module is used for determining a filtering threshold value of spectral polarization filtering by using JS divergence according to the difference of the spectral polarization parameters of a rainfall target and a non-rainfall target in statistical characteristics;
the second module is used for obtaining a range-Doppler image of the spectral polarization parameter of the original radar recovery data, and filtering the spectral polarization parameter by using the filtering threshold value to obtain a range-Doppler binary mask image;
and the third module is used for performing clutter filtering and rainfall target identification based on the range-Doppler binary mask image.
In another aspect, the present invention provides a computer device comprising a memory and a processor, the memory storing a computer program, the processor implementing the steps in the adaptive spectral polarization filtering method for dual-polarized weather radar when executing the computer program.
In yet another aspect, the invention also provides a computer readable storage medium having stored thereon a computer program which, when being executed by a processor, carries out the steps in the adaptive spectral polarization filtering of said dual polarized weather radar.
Compared with the prior art, the invention has the advantages that:
the invention can correct the filtering threshold of the spectral polarization filtering, and adaptively select the filtering threshold according to the rainfall conditions in different directions. The method has better clutter suppression and rainfall retention performance.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a flow chart of an embodiment of the present invention.
FIG. 2 is a flowchart of selecting a threshold value using JS divergence;
FIG. 3 is a plot of the JS divergence for an azimuthal direction versus a filtering threshold, wherein (a) is a plot of the JS divergence for rainfall and non-rainfall targets versus the filtering threshold; (b) the relationship between the difference of JS divergence of the rainfall target and the non-rainfall target and the filtering threshold value is shown;
fig. 4 is a diagram of a spectral power comparison obtained by filtering with different methods according to an embodiment of the present invention, wherein (a) is a spectral power diagram obtained by filtering with a Moving spectral Depolarization Ratio (MsDR) filter proposed by j.yin et al; (b) is a spectral power diagram obtained by filtering with the method of the invention;
fig. 5 is a reflectivity comparison graph obtained by filtering with different methods according to an embodiment of the present invention, wherein (a) is a reflectivity graph obtained by filtering with a Moving spectral Depolarization Ratio (MsDR) filter proposed by j.yin et al; (b) is a reflectivity map obtained by filtering by the method of the invention;
fig. 6 is a schematic structural diagram according to an embodiment of the present invention.
Detailed Description
For the purpose of promoting a clear understanding of the objects, aspects and advantages of the embodiments of the invention, reference will now be made to the drawings and detailed description, wherein there are shown in the drawings and described in detail, various modifications of the embodiments described herein, and other embodiments of the invention will be apparent to those skilled in the art. The exemplary embodiments of the present invention and the description thereof are provided to explain the present invention and not to limit the present invention.
In an embodiment of the present invention, a method for adaptive spectrum polarization filtering of a dual-polarization weather radar is provided, including:
s1, determining a filtering threshold value of spectral polarization filtering by using JS divergence according to the difference of spectral polarization parameters of a rainfall target and a non-rainfall target in statistical characteristics;
s2, obtaining a range-Doppler image of a spectral polarization parameter of original radar recovery data, and filtering the spectral polarization parameter by using the filtering threshold value to obtain a range-Doppler binary mask image;
and S3, performing clutter filtering and rainfall target identification based on the range-Doppler binary mask image.
For the JS divergence described in step S1, it is a parameter for comparing similarity or difference between two distributions based on the principle of information entropy, and it is defined as follows:
Figure BDA0003460753480000041
Figure BDA0003460753480000042
wherein: p (x) and Q (x) are normalized probability density functions of two different distributions, JS divergence JS (P | | Q) is 0 if the two probability distributions are identical, and JS divergence JS (P | | Q) is 1 if the two probability distributions are identical.
In the method of the invention, X denotes a spectral polarization parameter sDR (r, v) defined as:
Figure BDA0003460753480000043
wherein: r is distance, v is Doppler velocity, sZdr(r, v) is the spectral differential reflectivity, s ρco(r, v) is the spectral co-polarization correlation coefficient, the spectral differential reflectivity sZdr(r, v) and spectral co-polarization correlation coefficient s ρco(r, v) is defined as:
Figure BDA0003460753480000044
Figure BDA0003460753480000051
the probability distribution of the spectral polarization parameter X is different between clutter and rainfall targets and under the condition of no rainfall. And taking the probability distribution of the spectrum polarization parameter X under the rainfall-free condition as a reference, and respectively measuring the difference of the clutter and the rainfall target and the probability distribution of the spectrum polarization parameter X under the rainfall-free condition.
Specifically, in an embodiment of the present invention, as for the implementation method of step S1, the implementation method includes:
collecting multiple groups of radar echo data under the condition of no rainfall;
calculating the average probability distribution of spectrum polarization parameters on different azimuth angles in a plurality of groups of radar echo data under the condition of no rainfall;
and determining threshold values of spectral polarization filtering at different azimuth angles by using JS divergence based on the average probability distribution.
According to the existing grasped data situation, the skilled person can collect multiple groups of radar echo data under the rainfall-free condition as much as possible, and preferably collect more than 10 groups of radar echo data under the rainfall-free condition. And obtaining average probability distribution of spectrum polarization parameters on different azimuth angles in the multiple groups of radar echo data under the rainfall-free condition according to the collected multiple groups of radar echo data under the rainfall-free condition.
In an embodiment of the present invention
Figure BDA0003460753480000052
Based on the average probability distribution of spectral polarization parameters on azimuth angle alpha in the calculated multiple groups of radar echo data under the condition of no rainfall
Figure BDA0003460753480000053
And determining a threshold value for spectral polarization filtering at the azimuth angle alpha by using the JS divergence, comprising:
calculating JS divergence JS between spectrum polarization parameter X distribution under non-rainfall target and no-rainfall targetN(T)；
Figure BDA0003460753480000054
Calculating JS divergence JS between spectrum polarization parameter X distribution under rainfall target and rainfall-free target conditionP(T)；
Figure BDA0003460753480000055
Based on JSN(T) and JSP(T), calculating JSD(T)；
JSD(T)＝JSP(T)-JSN(T)
Where mask (X, α) ═ 0 denotes a non-rainfall target at azimuth α, P (X, α) denotes a normalized probability density function of X at azimuth α, P (X, α)mask(X,α)＝0Normalized probability density function, P (X, α), representing a quantity X, labeled non-rainfall target, at an azimuth αmask(X,α)＝1A normalized probability density function representing the quantity X, marked as a rainfall target, at the azimuth angle alpha,
Figure BDA0003460753480000061
is the condition of no rainfall of a plurality of groups on the azimuth angle alphaAverage probability distribution of lower parameter X, JSN(T) represents JS divergence between the X distribution at the non-rainfall target and the non-rainfall target; JS (JS)P(T) represents JS divergence between the rainfall target and the X distribution without the rainfall target;
Figure BDA0003460753480000062
representing the divergence between the non-rainfall target portion when the threshold is T and the probability distribution of the quantity X without rainfall target.
Fig. 2 is a flow chart of a method for determining an optimal spectral polarization filtering threshold at an azimuth angle α. When the rainfall echo is extracted to the maximum extent by using JS divergence, an optimal spectrum polarization filtering threshold value T is required to enable JS to be in contact withN(T) Small, JSP(T) is greater when JSD(T) when the maximum value is reached, the corresponding spectral polarization filtering threshold value T is the optimal threshold value Topt. The solving step specifically comprises:
(1) determining a search range [ T ] of the spectral polarization filtering threshold at the azimuth angle alphamin,Tmax]And a step value Δ T;
(2) for each spectral polarization filtering threshold T in the spectral polarization filtering threshold search range, based on
Figure BDA0003460753480000063
And JS divergence, solving JS divergence JS between the distribution of the spectrum polarization parameter X under the condition of the non-rainfall target and the non-rainfall target on the azimuth angle alphaN(T) and JS divergence JS between the distribution of spectral polarization parameters X at azimuth α and without rainfall targetP(T) and based on JSN(T) and JSP(T) calculating to obtain JSD(T)；
(3) To JSD(T) deriving if there is a threshold T make JS 'within the spectral polarization filtering threshold search range'D(T) is 0, then this threshold is the optimal threshold T for the spectral polarization filtering at the azimuth αopt(ii) a If not, make JS'DTaking JS as a threshold value of 0, i.e., no rainfall target in the azimuth angle αDThe threshold value T corresponding to the maximum value of (T) is optimal for the spectral polarization filtering at the azimuth angle alphaThreshold value Topt。
In one embodiment of the invention, the distribution of rainfall targets on the spectral polarization parameter X is used for determining the input spectral polarization filtering threshold search range Tmin,Tmax]. Taking the step value delta T (T) into consideration of calculation efficiency and filtering effectmax-Tmin)/100。
Referring to FIG. 3, which is a graph of JS divergence in a certain azimuth direction in relation to a filtering threshold value according to an embodiment of the present invention, in FIG. 3 (a) JS is shown at an azimuth angle of 316.9 °PThe relationship between divergence and the filtering threshold T, JS at this azimuth angle in FIG. 3 (b)DDivergence versus filtering threshold T, where T ═ 9.6 is JSDThe extreme point of (c). As can be seen from FIG. 3, when the threshold T is [ -15, -9.6 [ ]]At intervals, JSPDivergence increase speed greater than JSNDivergence, which means that as the threshold T increases, the number of retained rainfall targets increases, and the difference between the distribution characteristics of this part and the distribution characteristics under clear sky conditions becomes larger; when the threshold value T is [ -9.6, -5 [)]In the interval, the situation is opposite. Therefore, T is taken at an azimuth angle of 316.9 °opt＝-9.6dB。
In S2, for the range-doppler image of the spectral polarization parameter of the acquired original radar recovery data, the optimal spectral polarization filtering threshold is obtained by using the method provided in any of the above embodiments to filter the spectral polarization parameter, and clutter and noise are filtered out to obtain a range-doppler binary mask image.
For S3 of the present invention, clutter filtering and rainfall target identification are performed based on the range-doppler binary mask image. The skilled person can implement this based on any method available.
In an embodiment of the present invention, S3 includes S3.1, and based on the spectral width analysis of the band clutter, a one-dimensional doppler sliding window is set to select a rainfall target in the range-doppler binary mask image, so as to obtain a filtered binary mask image.
Further, in an embodiment of the present invention, S3 includes:
s3.1, setting a one-dimensional Doppler sliding window to select a rainfall target in the range-Doppler binary mask image based on spectral width analysis of the band clutter, and obtaining a filtered binary mask image;
and S3.2, in order to further filter the clutter and recover the lost rainfall signal, recovering the rainfall in the binary mask image obtained in the S3.1 by utilizing a 3 multiplied by 3 two-dimensional sliding window and filtering the clutter.
Aligning the center of the two-dimensional sliding window to the currently selected range-Doppler image unit in the binary mask image to obtain the corresponding values [ M ] of the currently selected range-Doppler image unit and the adjacent 8 range-Doppler image units0,M1,…,M9]The values corresponding to the currently selected range-doppler image element and the adjacent 8 range-doppler image elements adjacent to the currently selected range-doppler image element are 0 or 1 respectively, and then for M0,M1,…,M9Summing to obtain:
Figure BDA0003460753480000081
by setting a threshold value TRDTo determine the filter mask M of the currently selected range-Doppler image elementRDI.e. by
Figure BDA0003460753480000082
And traversing all range-Doppler image units in the binary mask image obtained by 3.1 by using a two-dimensional sliding window, so that clutter remaining in the binary mask image obtained by S3.1 can be further removed, and points near a rainfall region can be recovered.
After S3.2, clutter remaining in the binary mask image obtained in S3.1 can be further removed, and points near the rainfall area can be recovered, but points in the rainfall target area and at the boundary may be filtered out. Further, in an embodiment of the present invention, S3 includes:
s3.1, setting a one-dimensional Doppler sliding window to select a rainfall target in the range-Doppler binary mask image based on spectral width analysis of the band clutter, and obtaining a filtered binary mask image;
and S3.2, in order to further filter the clutter and recover the lost rainfall signal, recovering the rainfall in the binary mask image obtained in the S3.1 by utilizing a 3 multiplied by 3 two-dimensional sliding window and filtering the clutter.
And S3.3, recovering the rainfall target missing in the binary mask image obtained in the S3.2 by using the form closure of mathematical morphology, and obtaining the binary mask image after the rainfall target is recovered.
Specifically, the missing precipitation targets in the binary mask image obtained in S3.2 are restored by using a mathematical morphology close operation and setting the structural elements as a planar disk with a radius of 5. Through this process, a binary mask image after the rainfall target is restored is obtained.
To further supplement the remaining holes in the rainfall area, in an embodiment of the present invention, S3 includes:
s3.1, setting a one-dimensional Doppler sliding window to select a rainfall target in the range-Doppler binary mask image based on spectral width analysis of the band clutter, and obtaining a filtered binary mask image;
and S3.2, in order to further filter the clutter and recover the lost rainfall signal, recovering the rainfall in the binary mask image obtained in the S3.1 by utilizing a 3 multiplied by 3 two-dimensional sliding window and filtering the clutter.
And S3.3, recovering the rainfall target missing in the binary mask image obtained in the S3.2 by using the form closure of mathematical morphology, and obtaining the binary mask image after the rainfall target is recovered.
And S3.4, filling the medium-value mask image obtained in the S3.3 by using an image filling algorithm, and filling the hole into a value of a surrounding background by using the image filling algorithm when the hole remained in the rainfall area is closed.
Referring to fig. 4, a graph of spectral power comparison obtained by filtering with different methods according to an embodiment of the present invention is shown, wherein (a) is a graph of spectral power obtained by filtering with a Moving spectral Depolarization Ratio (MsDR) filter proposed by j.yin et al when the azimuth angle is 316.9 °; (b) is a spectral power diagram obtained by filtering with the method of the invention when the azimuth angle is 316.9 degrees. Comparing (a) and (b), both filtering can effectively remove ground clutter well separated from rainfall targets and band clutter overlapping with rainfall targets. At 5-8 Km, rainfall targets in the interior and at the edge of the meteorological target area in (a) are absent (circle in the figure). However, the filtering condition is greatly improved by using the method of the invention.
The method provided by the invention can filter most of clutter. By utilizing the spatial continuity of rainfall, the method filters residual clutter in PPI dimension. This filtering step acts on the PPI power map after spectral polarization filtering by generating a {0,1} binary filtering mask, using the formula in spectral polarization filtering step four and achieving preservation of rainfall targets and further filtering out clutter.
Referring to fig. 5, a reflectivity contrast diagram obtained by filtering with different methods according to an embodiment of the present invention is shown, wherein (a) is a reflectivity diagram obtained by filtering with a Moving spectral Depolarization Ratio (MsDR) filter proposed by j.yin et al; (b) is a reflectivity map obtained by filtering with the method of the invention. As can be seen from the figure, there are a large number of scatter points and the rainfall area is discontinuous in (a). In contrast, the reflectivity in (b) is less scattered and the rainfall area is more continuous.
The invention provides a self-adaptive spectrum polarization filtering device of a dual-polarization meteorological radar in an embodiment, which comprises:
the first module is used for determining a filtering threshold value of spectral polarization filtering by using JS divergence according to the difference of the spectral polarization parameters of a rainfall target and a non-rainfall target in statistical characteristics;
the second module is used for obtaining a range-Doppler image of the spectral polarization parameter of the original radar recovery data, and filtering the spectral polarization parameter by using the filtering threshold value to obtain a range-Doppler binary mask image;
and the third module is used for performing clutter filtering and rainfall target identification based on the range-Doppler binary mask image.
Further, in an embodiment of the present invention, the first module includes:
the database is used for collecting and storing a plurality of groups of radar echo data under the rainfall-free condition;
the first calculation module is used for calculating the average probability distribution of the spectral polarization parameters on different azimuth angles in a plurality of groups of radar echo data under the condition of no rainfall;
and the optimal threshold value determining module is used for determining the threshold values of the spectral polarization filtering at different azimuth angles by using the JS divergence based on the average probability distribution.
Further, in an embodiment of the present invention, the optimal threshold determining module includes:
an input module for determining a search range [ T ] of a spectral polarization filtering threshold at an azimuth angle alphamin,Tmax]And a step value Δ T;
a second calculation module for calculating a spectral polarization filtering threshold T for each spectral polarization filtering threshold within the spectral polarization filtering threshold search range based on Pcla(X, alpha) and JS divergence, and solving JS divergence between the distribution of the spectrum polarization parameter X under the condition of the non-rainfall target and the non-rainfall target on the azimuth angle alphaN(T) and JS divergence JS between the distribution of spectral polarization parameters X at azimuth α and without rainfall targetP(T) and based on JSN(T) and JSP(T) calculating to obtain JSD(T)；
Discrimination output module for JSD(T) deriving if there is a threshold T make JS 'within the spectral polarization filtering threshold search range'D(T) is 0, then this threshold is the optimal threshold T for the spectral polarization filtering at the azimuth αopt(ii) a If not, make JS'DTaking JS as a threshold value of 0, i.e., no rainfall target in the azimuth angle αDThe threshold T corresponding to the maximum value of (T) is the optimal threshold T for the spectral polarization filtering at the azimuth angle alphaopt。
The implementation method of the functions of the modules can be implemented by the same method in the foregoing embodiments, and details are not repeated here.
In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as shown in fig. 6. The computer device includes a processor, a memory, a network interface, and a database connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The database of the computer device is used to store sample data. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to realize the self-adaptive spectrum polarization filtering method of the dual-polarized weather radar.
Those skilled in the art will appreciate that the architecture shown in fig. 6 is merely a block diagram of some of the structures associated with the disclosed aspects and is not intended to limit the computing devices to which the disclosed aspects apply, as particular computing devices may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.
In one embodiment, a computer readable storage medium is provided, on which a computer program is stored, which when executed by a processor, performs the steps of the adaptive spectral polarization filtering method of the dual polarized weather radar in the above-described embodiments.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. The self-adaptive spectrum polarization filtering method of the dual-polarization meteorological radar is characterized by comprising the following steps of:
determining a filtering threshold value of spectral polarization filtering by using JS divergence according to the difference of the spectral polarization parameters of a rainfall target and a non-rainfall target in statistical characteristics;
obtaining a range-Doppler image of a spectral polarization parameter of original radar recovery data, and filtering the spectral polarization parameter by using the filtering threshold value to obtain a range-Doppler binary mask image;
and performing clutter filtering and rainfall target identification based on the range-Doppler binary mask image.
2. The adaptive spectral polarization filtering method of a dual polarized weather radar according to claim 1, wherein the method of determining the filtering threshold for spectral polarization filtering comprises:
collecting multiple groups of radar echo data under the condition of no rainfall;
calculating the average probability distribution of spectrum polarization parameters on different azimuth angles in a plurality of groups of radar echo data under the condition of no rainfall;
and determining threshold values of spectral polarization filtering at different azimuth angles by using JS divergence based on the average probability distribution.
3. The adaptive spectral polarization filtering method of dual polarized weather radar of claim 2, wherein it is assumed that
Figure FDA0003460753470000011
Based on the average probability distribution of spectral polarization parameters on azimuth angle alpha in the calculated multiple groups of radar echo data under the condition of no rainfall
Figure FDA0003460753470000012
And determining a threshold value for spectral polarization filtering at the azimuth angle alpha by using the JS divergence, comprising:
(1) determining a search range [ T ] of the spectral polarization filtering threshold at the azimuth angle alphamin,Tmax]And a step value Δ T;
(2) for each spectral polarization filtering threshold T in the spectral polarization filtering threshold search range, based on Pcla(X, alpha) and JS divergence, and solving JS divergence between the distribution of the spectrum polarization parameter X under the condition of the non-rainfall target and the non-rainfall target on the azimuth angle alphaN(T) and JS divergence JS between the distribution of spectral polarization parameters X at azimuth α and without rainfall targetP(T) and based on JSN(T) and JSP(T) calculating to obtain JSD(T)；
(3) To JSD(T) deriving if there is a threshold T make JS 'within the spectral polarization filtering threshold search range'D(T) is 0, then this threshold is the optimal threshold T for the spectral polarization filtering at the azimuth αopt(ii) a If not, make JS'DThreshold value of (T) ═ 0, i.e. at this orientationNo rainfall target in angle alpha, take JSDThe threshold T corresponding to the maximum value of (T) is the optimal threshold T for the spectral polarization filtering at the azimuth angle alphaopt。
4. The adaptive spectral polarization filtering method for dual-polarized weather radar of claim 3, wherein JSN(T)、JSP(T) and JSDThe calculation formula of (T) is respectively as follows:
Figure FDA0003460753470000021
Figure FDA0003460753470000022
JSD(T)＝JSP(T)-JSN(T)
where mask (X, α) ═ 0 denotes a non-rainfall target at azimuth α, P (X, α) denotes a normalized probability density function of X at azimuth α, P (X, α)mask(X,α)＝0Normalized probability density function, P (X, α), representing a quantity X, labeled non-rainfall target, at an azimuth αmask(X,α)＝1A normalized probability density function representing the quantity X, marked as a rainfall target, at the azimuth angle alpha,
Figure FDA0003460753470000023
is the average probability distribution of the parameter X under the condition of no rainfall of a plurality of groups on the azimuth angle alpha, in the formula
Figure FDA0003460753470000024
Representing the divergence between the non-rainfall target portion when the threshold is T and the probability distribution of the quantity X without rainfall target.
5. The adaptive spectral polarization filtering method for dual-polarized weather radar according to any one of claims 1 to 4, wherein the clutter filtering and rainfall target identification based on range-Doppler binary mask images comprises:
and S3.1, setting a one-dimensional Doppler sliding window to select a rainfall target in the range-Doppler binary mask image based on spectral width analysis of the band clutter, and obtaining the filtered binary mask image.
6. The adaptive spectral polarization filtering method for dual polarized weather radar according to claim 4, wherein the clutter filtering and rainfall target identification based on range-Doppler binary mask images further comprises:
and S3.2, recovering rainfall in the binary mask image obtained in the S3.1 by utilizing a 3 multiplied by 3 two-dimensional sliding window and filtering out clutter.
7. The adaptive spectral polarization filtering method for dual polarized weather radar according to claim 4, wherein the clutter filtering and rainfall target identification based on range-Doppler binary mask images further comprises:
and S3.3, recovering the rainfall target missing in the binary mask image obtained in the S3.2 by using the form closure of mathematical morphology, and obtaining the binary mask image after the rainfall target is recovered.
8. The adaptive spectral polarization filtering method for dual polarized weather radar according to claim 4, wherein the clutter filtering and rainfall target identification based on range-Doppler binary mask images further comprises:
and S3.4, filling the medium-value mask image obtained in the S3.3 by using an image filling algorithm, and filling the hole into a value of a surrounding background by using the image filling algorithm when the hole remained in the rainfall area is closed.
9. Dual polarization weather radar's self-adaptation spectrum polarization filter equipment, its characterized in that includes:
the first module is used for determining a filtering threshold value of spectral polarization filtering by using JS divergence according to the difference of the spectral polarization parameters of a rainfall target and a non-rainfall target in statistical characteristics;
the second module is used for obtaining a range-Doppler image of the spectral polarization parameter of the original radar recovery data, and filtering the spectral polarization parameter by using the filtering threshold value to obtain a range-Doppler binary mask image;
and the third module is used for performing clutter filtering and rainfall target identification based on the range-Doppler binary mask image.
10. The adaptive spectral polarization filtering apparatus of a dual polarized weather radar of claim 9, wherein the first module comprises:
the database is used for collecting and storing a plurality of groups of radar echo data under the rainfall-free condition;
the first calculation module is used for calculating the average probability distribution of the spectral polarization parameters on different azimuth angles in a plurality of groups of radar echo data under the condition of no rainfall;
and the optimal threshold value determining module is used for determining the threshold values of the spectral polarization filtering at different azimuth angles by using the JS divergence based on the average probability distribution.
CN202210017954.8A 2022-01-07 2022-01-07 Self-adaptive spectrum polarization filtering method and device of dual-polarized weather radar Pending CN114355357A (en)

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