Cloud visibility inversion method based on three-frequency-band radar

Abstract

The invention discloses a cloud visibility inversion method based on a three-frequency-band radar, and relates to the technical field of meteorology. According to the method, three radars in different frequency bands are used for jointly detecting a cloud meteorological target, two millimeter wave radars can be used for obtaining reflectivity factors of the cloud meteorological target in different frequency bands, a visibility laser radar can be used for obtaining extinction coefficients of the cloud meteorological target, and a visibility gradual inversion method is used for obtaining the cloud meteorological target. And the radar observation values are inverted and fused by fully utilizing the characteristics of the overlapped region of the radars of different frequency bands, so that the visibility inversion result in the complete cloud and fog detection region can be obtained. Detection can be carried out on a shorter frequency band by introducing the W-frequency-band millimeter wave radar, and the defect that the Ka frequency band is insufficient in small particle detection capability is overcome, so that the visibility inversion accuracy is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of meteorological technology, and in particular to a cloud and fog visibility inversion method based on a three-band radar. Background Art

[0002] The visibility of clouds and fog, Vis (Visibility), is an important parameter used to describe the concentration of clouds and fog. Currently, there are many methods to invert visibility by observing multiple microphysical parameters of clouds and fog, which has high practical significance.

[0003] In recent years, with the development of radar detection technology, more and more studies have attempted to obtain visibility information of clouds and fog from radar observations by establishing the relationship between the radar reflectivity factor of cloud and fog echoes and visibility Vis. However, the relationship between the radar reflectivity factor and visibility Vis is highly dependent on the droplet spectrum distribution, so it cannot provide accurate visibility inversion results and always requires auxiliary data from optical sensors such as microwave radiometers and ceilometers. Summary of the invention

[0004] In response to the above problems and technical requirements, this application proposes a cloud and fog visibility inversion method based on a three-band radar. The technical solution of this application is as follows:

[0005] A cloud and fog visibility inversion method based on a three-band radar, the cloud and fog visibility inversion method comprising:

[0006] The Ka-band millimeter-wave radar, W-band millimeter-wave radar and lidar are used to synchronously scan the same cloud and fog meteorological target and obtain the time-space matching radar observation values. The radar observation values ​​include the Ka-band reflectivity factor in the complete cloud and fog detection area obtained by the Ka-band millimeter-wave radar, the W-band reflectivity factor in the corresponding detection area obtained by the W-band millimeter-wave radar, and the extinction coefficient observation value Ext in the corresponding detection area obtained by the lidar. 1 ;

[0007] A first extinction coefficient fitting equation is obtained according to radar observation values ​​in the three-radar detection area; wherein the three-radar detection area is a detection area covered by three radars;

[0008] The extinction coefficient inversion value Ext in the dual radar detection area is obtained by combining the first extinction coefficient fitting equation with the radar observation value in the dual radar detection area. 2 and a second extinction coefficient fitting equation; wherein the dual radar detection area is a detection area not covered by the laser radar but covered by two millimeter wave radars;

[0009] The second extinction coefficient fitting equation is combined with the Ka-band reflectivity factor in the non-overlapping detection area. Get the extinction coefficient inversion value Ext in the non-overlapping detection area 3 ; Among them, the non-overlapping detection area is the detection area covered only by the Ka-band millimeter-wave radar;

[0010] Comprehensive extinction coefficient observation value Ext 1 , extinction coefficient inversion value Ext 2 and extinction coefficient inversion value Ext 3 The extinction coefficient in the complete cloud and fog detection area is obtained, and the visibility inversion result in the complete cloud and fog detection area is obtained according to the extinction coefficient in the complete cloud and fog detection area.

[0011] A further technical solution is to obtain a first extinction coefficient fitting equation according to radar observations in the three radar detection areas, including:

[0012] According to the Ka-band reflectivity factor within the detection area of ​​the three radars and W-band reflectivity factor The liquid water content LWC at different heights in the three radar detection areas is calculated 1 ;

[0013] According to the Ka-band reflectivity factor within the detection area of ​​the three radars Extinction coefficient observation value Ext 1 , Liquid water content LWC 1 The first extinction coefficient fitting equation is obtained by fitting. The first extinction coefficient fitting equation indicates the extinction coefficient Ext and the Ka-band reflectivity factor Z at any position in the detection area of ​​the three radars. Ka And the functional relationship between the liquid water content LWC at the corresponding height.

[0014] Its further technical solution is to obtain the extinction coefficient inversion value Ext in the dual radar detection area 2 include:

[0015] According to the Ka-band reflectivity factor in the dual radar detection area and W-band reflectivity factor The liquid water content LWC at different heights in the dual radar detection area is calculated 2 ;

[0016] The Ka-band reflectivity factor at any position in the dual radar detection area and the liquid water content LWC at the corresponding height 2 Substitute the first extinction coefficient fitting equation to calculate the extinction coefficient inversion value Ext in the dual radar detection area. 2 .

[0017] A further technical solution is to calculate the liquid water content at different heights in the three-radar detection area or the dual-radar detection area, including:

[0018] according to Calculate the liquid water content LWC(h1) at any height h1;

[0019] Among them, DWR h2 is the difference between the Ka-band reflectivity factor and the W-band reflectivity factor at height h2, DWR h1 It is the difference between the Ka-band reflectivity factor and the W-band reflectivity factor at height h1. Height h2 is the height corresponding to the next range gate of the range gate corresponding to height h1. A is the difference in attenuation coefficients of unit liquid water content for Ka-band and W-band. B is a parameter.

[0020] Its further technical solution is to use the Ka-band reflectivity factor within the detection area of ​​the three radars Extinction coefficient observation value Ext 1 , Liquid water content LWC 1 The fitting equation of the first extinction coefficient includes:

[0021] The extinction coefficient observation value Ext in the three radar detection areas 1 and liquid water content LWC 1 Perform logarithmic operation preprocessing respectively to obtain the processed extinction coefficient observation value Ext in the three radar detection areas 1 ′ and liquid water content LWC after treatment 1 ′;

[0022] The Ka-band reflectivity factor in the detection area of ​​the three radars Ext value of extinction coefficient after processing 1 ', Liquid water content after treatment LWC 1 ′ is fitted by the least square method in the form of a multivariate linear regression equation to obtain the processed extinction coefficient Ext′ and the Ka-band reflectivity factor Z at any position in the detection area of ​​the three radars. Ka The first extinction coefficient fitting equation Ext′=c+a×LWC′+n×Z Ka , a, n and c are the coefficients obtained by fitting.

[0023] A further technical solution is to calculate the extinction coefficient observation value Ext in the detection area of ​​the three radars. 1 and liquid water content LWC 1 The logarithmic operation preprocessing includes:

[0024] According to Ext 1′=10lg(Ext 1 ) The extinction coefficient observation value Ext in the three radar detection areas 1 Perform logarithmic operation preprocessing to obtain the processed extinction coefficient observation value Ext in the three radar detection areas 1 ′;

[0025] Follow LWC 1 ′=10lg(LWC 1 ) The liquid water content LWC in the three radar detection areas 1 Perform logarithmic operation preprocessing to obtain the processed liquid water content LWC in the three radar detection areas 1 ′.

[0026] A further technical solution is to calculate the extinction coefficient inversion value Ext in the dual radar detection area. 2 include:

[0027] Follow LWC 2 ′=10lg(LWC 2 ) for the liquid water content LWC in the dual radar detection area 2 Perform logarithmic operation preprocessing to obtain the processed liquid water content LWC in the dual radar detection area 2 ′;

[0028] The processed liquid water content LWC in the dual radar detection area 2 Substitute ′ into the processed liquid water content LWC′ in the first extinction coefficient fitting equation, and convert the Ka-band reflectivity factor in the dual radar detection area into Substitute the Ka-band reflectivity factor Z into the first extinction coefficient fitting equation Ka , the calculated processed extinction coefficient Ext′ is used as the processed extinction coefficient Ext in the dual radar detection area 2 ′;

[0029] according to Get the extinction coefficient inversion value Ext in the dual radar detection area 2 .

[0030] A further technical solution is that obtaining the second extinction coefficient fitting equation includes:

[0031] Ka-band reflectivity factor in the dual radar detection area and extinction coefficient inversion value Ext 2 The least square method is used to fit the linear regression equation to obtain the indicated extinction coefficient Ext and the Ka-band reflectivity factor Z. Ka The second extinction coefficient fitting equation Ext = d × Z Ka+e, d and e are the coefficients obtained by fitting.

[0032] A further technical solution is to obtain the extinction coefficient inversion value Ext in the non-overlapping detection area. 3 include:

[0033] The Ka-band reflectivity factor in the non-overlapping detection area Substitute the Ka-band reflectivity factor Z into the second extinction coefficient fitting equation Ka , the calculated extinction coefficient Ext is used as the processed extinction coefficient Ext′ in the non-overlapping detection area 3 ;

[0034] according to Get the extinction coefficient inversion value Ext in the non-overlapping detection area 3 .

[0035] A further technical solution is to obtain the visibility inversion result in the complete cloud and fog detection area according to the extinction coefficient in the complete cloud and fog detection area, including:

[0036] The extinction coefficient Ext at any position in the complete cloud and fog detection area is calculated according to The corresponding visibility inversion results are calculated.

[0037] The beneficial technical effects of this application are:

[0038] The present application discloses a cloud and fog visibility inversion method based on three-band radar. The method uses three-band radars to jointly detect cloud and fog meteorological targets. Two millimeter-wave radars can be used to obtain the reflectivity factors of cloud and fog meteorological targets in different frequency bands. A laser radar can be used to obtain the extinction parameters of cloud and fog meteorological targets. A visibility step-by-step inversion method is adopted to fully utilize the characteristics of the overlapping areas of radars in different frequency bands, invert and fuse the observation values, and make full use of the effective observation values. The use of W-band millimeter-wave radar can detect in a shorter frequency band, making up for the shortcoming of the Ka-band's insufficient detection capability of small particles, and thus has better visibility inversion accuracy.

[0039] The liquid water content can be inverted by utilizing the difference in the attenuation characteristics of particles at the Ka band and the W band. By introducing this information into the relationship between the reflectivity factor and visibility, the relationship between liquid water content and visibility can be further quantified when the reflectivity factor is the same, thereby further improving the accuracy of visibility inversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a flow chart of a cloud and fog visibility inversion method according to an embodiment of the present application.

[0041] Figure 2It is a schematic diagram of the detection area of ​​the three frequency band radars used in this application.

[0042] Figure 3 It is a flow chart of a cloud and fog visibility inversion method according to another embodiment of the present application. DETAILED DESCRIPTION

[0043] The specific implementation of the present application is further described below in conjunction with the accompanying drawings.

[0044] This application discloses a cloud and fog visibility inversion method based on a three-band radar. Please refer to Figure 1 As shown in the flowchart, the cloud visibility inversion method includes the following steps:

[0045] Step 1: Use Ka-band millimeter-wave radar, W-band millimeter-wave radar and lidar to synchronously scan the same cloud and fog meteorological target and obtain radar observation values ​​that match time and space.

[0046] The radar observation values ​​obtained include the Ka-band reflectivity factor in the complete cloud and fog detection area obtained by the Ka-band millimeter-wave radar, the W-band reflectivity factor in the corresponding detection area obtained by the W-band millimeter-wave radar, and the extinction coefficient observation value Ext in the corresponding detection area obtained by the lidar. 1 The raw data detected by the three frequency band radars may not match in time and space, so the raw data must first be uniformly interpolated to the same time, the same range gate, and the same radial direction to complete time and space matching.

[0047] This application uses two millimeter-wave radars of different frequency bands in combination with a lidar to jointly detect cloud and fog meteorological targets to obtain observation data. The W-band millimeter-wave radar can detect at a shorter frequency band, which can make up for the shortcomings of the Ka-band millimeter-wave radar in its insufficient detection capability for small particles.

[0048] According to the attenuation characteristics of cloud and fog meteorological targets for radars of different frequency bands, the Ka-band millimeter-wave radar can obtain the largest range of cloud and fog meteorological targets, the W-band millimeter-wave radar can obtain a smaller range of cloud and fog meteorological targets, and the laser radar can obtain the smallest range of cloud and fog meteorological targets. Please refer to Figure 2 A schematic diagram showing the detection areas of the three frequency band radars respectively.

[0049] The detection areas of radars of different frequency bands may overlap. This application defines the detection area covered by all three radars as the three-radar detection area P1. The detection area not covered by the laser radar but covered by two millimeter-wave radars is the dual-radar detection area P2. The detection area covered only by the Ka-band millimeter-wave radar but not by the other two radars is the non-overlapping detection area P3. Figure 2Taking the detection area of ​​​​the Ka-band millimeter-wave radar as an example, the detection area of ​​​​the W-band millimeter-wave radar completely covers the detection area of ​​​​the W-band millimeter-wave radar, and the detection area of ​​​​the W-band millimeter-wave radar completely covers the detection area of ​​​​the lidar. Based on this, the detection area of ​​​​the lidar is the three-radar detection area P1, and the union of the three-radar detection area P1 and the dual-radar detection area P2 is the detection area of ​​​​the W-band millimeter-wave radar. The union of the three-radar detection area P1, the dual-radar detection area P2 and the non-overlapping detection area P3 is the detection area of ​​​​the Ka-band millimeter-wave radar, which is also a complete cloud and fog detection area.

[0050] Step 2: obtaining a first extinction coefficient fitting equation according to the radar observation values ​​in the three radar detection areas P1, wherein the first extinction coefficient fitting equation indicates a functional relationship between the extinction coefficient at any position in the three radar detection areas P1 and the radar observation values.

[0051] Based on the above introduction, the radar observation values ​​in the three-radar detection area P1 include the detection data of all three radars. In order to distinguish the radar observation values ​​in different areas, the parameter subscript is introduced and the radar observation values ​​in the three-radar detection area P1 are defined to include the Ka-band reflectivity factor W-band reflectivity factor Extinction coefficient observation value Ext 1 .

[0052] In another embodiment, the following steps are included when establishing the first extinction coefficient fitting equation. Figure 3 The flowchart shown:

[0053] 1. Based on the Ka-band reflectivity factor within the detection area of ​​the three radars and W-band reflectivity factor The liquid water content LWC at different heights in the three radar detection areas is calculated 1 .

[0054] This step uses the difference in the attenuation characteristics of particles for the Ka band and the W band to invert the liquid water content. The liquid water content LWC(h1) at any height h1 is calculated according to the following formula:

[0055]

[0056] Among them, DWR h2 is the difference between the Ka-band reflectivity factor and the W-band reflectivity factor at height h2, DWR h1is the difference between the Ka-band reflectivity factor and the W-band reflectivity factor at height h1. Height h2 is the height corresponding to the next range gate of the range gate corresponding to height h1. A is the difference between the attenuation coefficients of the unit liquid water content to the Ka-band and the W-band, which is calculated according to the empirical formula. B is a parameter related to the difference in the attenuation coefficients of the atmosphere and liquid particles to the Ka-band and the W-band, which is also calculated according to the empirical formula.

[0057] 2. Based on the Ka-band reflectivity factor within the detection area of ​​the three radars Extinction coefficient observation value Ext 1 , Liquid water content LWC 1 The first extinction coefficient fitting equation was obtained by fitting.

[0058] That is, this embodiment also introduces the information of liquid water content, so that the first extinction coefficient fitting equation further indicates the extinction coefficient Ext and the Ka-band reflectivity factor Z at any position in the three radar detection areas. Ka This approach can further quantify the relationship between liquid water content and visibility when the reflectivity factor is the same, which is conducive to improving the accuracy of visibility inversion.

[0059] In addition, in order to facilitate the fitting calculation, the radar observation values ​​are not directly fitted, but the extinction coefficient observation values ​​Ext in the three radar detection areas are first fitted. 1 and liquid water content LWC 1 Perform logarithmic operation preprocessing respectively to obtain the processed extinction coefficient observation value Ext in the three radar detection areas 1 ′ and liquid water content LWC after treatment 1 '. Including: According to Ext 1 ′=10lg(Ext 1 ) The extinction coefficient observation value Ext in the three radar detection areas 1 Perform logarithmic operation preprocessing to obtain the processed extinction coefficient observation value Ext in the three radar detection areas 1 '. And, according to LWC 1 ′=10lg(LWC 1 ) The liquid water content LWC in the three radar detection areas 1 Perform logarithmic operation preprocessing to obtain the processed liquid water content LWC in the three radar detection areas 1 ′.

[0060] Then the Ka-band reflectivity factor in the detection area of ​​the three radars is Ext value of extinction coefficient after processing 1 ', Liquid water content after treatment LWC 1'The least square method is used to fit in the form of a multivariate linear regression equation to obtain the first extinction coefficient fitting equation Ext' = c + a × LWC' + n × Z Ka The first extinction coefficient fitting equation obtained thereby indicates the processed extinction coefficient Ext′ and the Ka-band reflectivity factor Z at any position in the detection area of ​​the three radars. Ka The functional relationship between the treated liquid water content LWC′ and the corresponding height, a, n and c are the fitting coefficients.

[0061] Step 3: Use the first extinction coefficient fitting equation combined with the radar observations in the dual radar detection area to obtain the extinction coefficient inversion value Ext in the dual radar detection area. 2 and the second extinction coefficient fitting equation.

[0062] The radar observation value in the dual radar detection area P2 includes the Ka-band reflectivity factor and the W-band reflectivity factor. Similarly, for the convenience of distinction, the subscript definition is introduced to define that the radar observation value in the dual radar detection area P2 includes the Ka-band reflectivity factor and W-band reflectivity factor

[0063] Based on spatial continuity and statistical similarity, the characteristics of the dual radar detection area and the triple radar detection area can be considered similar. Since the two areas are consistent in physical characteristics, the first extinction coefficient fitting equation obtained by fitting the triple radar detection area can be extrapolated to the dual radar detection area. Therefore, the radar observation value at any position in the dual radar detection area is substituted into the first extinction coefficient fitting equation to obtain the extinction coefficient inversion value Ext at the corresponding position. 2 The extinction coefficient inversion value obtained by this extrapolation method helps to maintain the continuity and consistency of meteorological target detection. In addition, if the local observation results in the dual-radar detection area show a good correlation with the fitting values ​​in the three-radar detection area, the reliability of this method will be further enhanced. The validity of the extrapolation results can be verified through error analysis, thus providing theoretical support for this method.

[0064] In one embodiment, based on the introduction of the information of liquid water content into the first extinction coefficient fitting equation obtained in step 2, this step also first calculates the Ka-band reflectivity factor in the dual radar detection area. and W-band reflectivity factor The liquid water content LWC at different heights in the dual radar detection area is calculated 2 The calculation method is the same as the above method for calculating the liquid water content at different heights in the three radar detection areas, and will not be repeated here.

[0065] Then the Ka-band reflectivity factor at any position in the dual radar detection area is and the liquid water content LWC at the corresponding height 2 Substituting the first extinction coefficient fitting equation obtained above, the extinction coefficient inversion value Ext at different positions in the dual radar detection area can be calculated. 2 .

[0066] As above, for the convenience of processing, the first extinction coefficient fitting equation obtained will adopt Ext′=c+a×LWC′+b×Z Ka In the form of, correspondingly, the Ka-band reflectivity factor at any position in the dual radar detection area and the liquid water content LWC at the corresponding height 2 When substituting into the first extinction coefficient fitting equation, first follow the LWC 2 ′=10lg(LWC 2 ) for the liquid water content LWC in the dual radar detection area 2 Perform logarithmic operation preprocessing to obtain the processed liquid water content LWC in the dual radar detection area 2 ′. Then the processed liquid water content LWC in the dual radar detection area is 2 Substitute ′ into the processed liquid water content LWC′ in the first extinction coefficient fitting equation, and convert the Ka-band reflectivity factor in the dual radar detection area into Substitute the Ka-band reflectivity factor Z into the first extinction coefficient fitting equation Ka , the calculated processed extinction coefficient Ext′ is used as the processed extinction coefficient Ext in the dual radar detection area 2 ′. Finally, follow Get the extinction coefficient inversion value Ext in the dual radar detection area 2 .

[0067] Get the extinction coefficient inversion value Ext in the dual radar detection area 2 After that, we can further combine the Ka-band reflectivity factor in the dual radar detection area To obtain the second extinction coefficient fitting equation, specifically: the Ka-band reflectivity factor in the dual radar detection area and extinction coefficient inversion value Ext 2 The least square method is used to fit the second extinction coefficient fitting equation Ext = d × Z Ka +e, the second extinction coefficient fitting equation is used to indicate the extinction coefficient Ext and the Ka-band reflectivity factor Z Ka The functional relationship between them.

[0068] Step 4: Use the second extinction coefficient fitting equation combined with the Ka-band reflectivity factor in the non-overlapping detection area Get the extinction coefficient inversion value Ext in the non-overlapping detection area 3 The radar observation value in the non-overlapping detection area P3 only has the Ka-band reflectivity factor. Similarly, the subscript is introduced to distinguish it. The Ka-band reflectivity factor in the non-overlapping detection area P3 is defined as

[0069] Similarly, based on spatial continuity and statistical similarity, the characteristics of the non-overlapping detection area and the dual radar detection area can be considered similar. Since the two areas are consistent in physical characteristics, the second extinction coefficient fitting equation obtained by fitting the dual radar detection area can be extrapolated to the non-overlapping detection area. Substitute the Ka-band reflectivity factor Z into the second extinction coefficient fitting equation Ka , the calculated extinction coefficient Ext is used as the processed extinction coefficient Ext′ in the non-overlapping detection area 3 Finally follow Get the extinction coefficient inversion value Ext in the non-overlapping detection area 3 .

[0070] Step 5: Comprehensive extinction coefficient observation value Ext 1 , extinction coefficient inversion value Ext 2 and extinction coefficient inversion value Ext 3 The extinction coefficient in the complete cloud and fog detection area is obtained, and the visibility inversion result in the complete cloud and fog detection area is obtained according to the extinction coefficient in the complete cloud and fog detection area. Including the extinction coefficient Ext at any position in the complete cloud and fog detection area according to The corresponding visibility inversion results are calculated.

[0071] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A cloud and fog visibility inversion method based on a three-band radar, characterized in that: The cloud and fog visibility inversion method comprises: The Ka-band millimeter-wave radar, the W-band millimeter-wave radar and the laser radar are used to synchronously scan the same cloud and fog meteorological target and obtain the radar observation values ​​matched in time and space, wherein the radar observation values ​​include the Ka-band reflectivity factor in the complete cloud and fog detection area obtained by the Ka-band millimeter-wave radar, the W-band reflectivity factor in the corresponding detection area obtained by the W-band millimeter-wave radar, and the extinction coefficient observation value Ext1 in the corresponding detection area obtained by the laser radar; A first extinction coefficient fitting equation is obtained according to radar observation values ​​in the three-radar detection area; wherein the three-radar detection area is a detection area covered by three radars; The extinction coefficient inversion value Ext2 and the second extinction coefficient fitting equation in the dual radar detection area are obtained by using the first extinction coefficient fitting equation in combination with the radar observation value in the dual radar detection area; wherein the dual radar detection area is a detection area not covered by the laser radar but covered by two millimeter wave radars; The second extinction coefficient fitting equation is combined with the Ka-band reflectivity factor in the non-overlapping detection area. Obtaining an extinction coefficient inversion value Ext3 in a non-overlapping detection area; wherein the non-overlapping detection area is a detection area covered only by the Ka-band millimeter-wave radar; The extinction coefficient in the complete cloud and fog detection area is obtained by combining the extinction coefficient observation value Ext1, the extinction coefficient inversion value Ext2 and the extinction coefficient inversion value Ext3. The visibility inversion result in the complete cloud and fog detection area is obtained according to the extinction coefficient in the complete cloud and fog detection area.

2. The cloud and fog visibility inversion method according to claim 1, characterized in that: The first extinction coefficient fitting equation obtained according to the radar observation values ​​in the three radar detection areas includes: According to the Ka-band reflectivity factor within the detection area of ​​the three radars and W-band reflectivity factor The liquid water content LWC1 at different heights in the detection area of ​​the three radars was calculated; According to the Ka-band reflectivity factor within the detection area of ​​the three radars The first extinction coefficient fitting equation is obtained by fitting the extinction coefficient observation value Ext1 and the liquid water content LWC1. The first extinction coefficient fitting equation indicates the extinction coefficient Ext and the Ka-band reflectivity factor Z at any position in the three radar detection areas. Ka And the functional relationship between the liquid water content LWC at the corresponding height.

3. The cloud and fog visibility inversion method according to claim 2, characterized in that: The obtaining of the extinction coefficient inversion value Ext2 in the dual radar detection area includes: According to the Ka-band reflectivity factor in the dual radar detection area and W-band reflectivity factor The liquid water content LWC2 at different heights in the dual radar detection area is calculated; The Ka-band reflectivity factor at any position in the dual radar detection area The liquid water content LWC2 at the corresponding height is substituted into the first extinction coefficient fitting equation to calculate the extinction coefficient inversion value Ext2 in the dual radar detection area.

4. The cloud and fog visibility inversion method according to claim 2 or 3, characterized in that: The calculated liquid water content at different heights in the three-radar detection area or the dual-radar detection area includes: according to Calculate the liquid water content LWC(h1) at any height h1; Among them, DWR h2 is the difference between the Ka-band reflectivity factor and the W-band reflectivity factor at height h2, DWR h1 It is the difference between the Ka-band reflectivity factor and the W-band reflectivity factor at height h1. Height h2 is the height corresponding to the next range gate of the range gate corresponding to height h1. A is the difference in attenuation coefficients of unit liquid water content for Ka-band and W-band. B is a parameter.

5. The cloud and fog visibility inversion method according to claim 3, characterized in that: The Ka-band reflectivity factor in the detection area of ​​the three radars The first extinction coefficient fitting equation obtained by fitting the extinction coefficient observation value Ext1 and the liquid water content LWC1 includes: Perform logarithmic operation preprocessing on the extinction coefficient observation values ​​Ext1 and the liquid water content LWC1 in the three radar detection areas, respectively, to obtain the processed extinction coefficient observation values ​​Ext1′ and the processed liquid water content LWC1′ in the three radar detection areas; The Ka-band reflectivity factor in the detection area of ​​the three radars The processed extinction coefficient observation value Ext1′ and the processed liquid water content LWC1′ are fitted in the form of a multivariate linear regression equation using the least squares method to obtain the processed extinction coefficient Ext′ and Ka-band reflectivity factor Z at any position in the detection area of ​​the three radars. Ka The first extinction coefficient fitting equation Ext′=c+a×LW C ′+b×Z Ka , a, b and c are the coefficients obtained by fitting.

6. The cloud and fog visibility inversion method according to claim 5, characterized in that: The logarithmic operation preprocessing of the extinction coefficient observation value Ext1 and the liquid water content LWC1 in the three radar detection areas comprises: According to Ext1′=101g(Ext1), the extinction coefficient observation value Ext1 in the three radar detection areas is preprocessed by logarithmic operation to obtain the processed extinction coefficient observation value Ext1′ in the three radar detection areas; The liquid water content LWC1 in the three radar detection areas is preprocessed by logarithmic operation according to LWC1′=101g(LWC1) to obtain the processed liquid water content LWC1′ in the three radar detection areas.

7. The cloud and fog visibility inversion method according to claim 5, characterized in that: The extinction coefficient inversion value Ext2 in the dual radar detection area is calculated and obtained by: According to LWC2′=101g(LWC2), the liquid water content LWC2 in the dual radar detection area is pre-processed by logarithmic operation to obtain the processed liquid water content LWC2′ in the dual radar detection area; Substitute the processed liquid water content LWC2′ in the dual radar detection area into the processed liquid water content LWC′ in the first extinction coefficient fitting equation, and substitute the Ka-band reflectivity factor LWC2′ in the dual radar detection area. Substitute the Ka-band reflectivity factor Z into the first extinction coefficient fitting equation Ka , the calculated processed extinction coefficient Ext′ is used as the processed extinction coefficient Ext2′ in the dual radar detection area; according to The extinction coefficient inversion value Ext2 in the dual radar detection area is obtained.

8. The cloud and fog visibility inversion method according to claim 1, characterized in that: The fitting equation for the second extinction coefficient includes: Ka-band reflectivity factor in the dual radar detection area The inversion value of the extinction coefficient Ext2 is fitted by the least square method in the form of a linear regression equation to obtain the indicated extinction coefficient Ext and the Ka-band reflectivity factor Z Ka The second extinction coefficient fitting equation Ext = d × Z Ka +e, d and e are the coefficients obtained by fitting.

9. The cloud and fog visibility inversion method according to claim 8, characterized in that: The obtaining of the extinction coefficient inversion value Ext3 in the non-overlapping detection area includes: The Ka-band reflectivity factor in the non-overlapping detection area Substitute the Ka-band reflectivity factor Z into the second extinction coefficient fitting equation Ka , the calculated extinction coefficient Ext is used as the processed extinction coefficient Ext′3 in the non-overlapping detection area; according to The extinction coefficient inversion value Ext3 in the non-overlapping detection area is obtained.

10. The cloud and fog visibility inversion method according to claim 1, characterized in that: The visibility inversion result in the complete cloud and fog detection area is obtained according to the extinction coefficient in the complete cloud and fog detection area, including: The extinction coefficient Ext at any position in the complete cloud and fog detection area is calculated according to The corresponding visibility inversion results are calculated.

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