KR102632005B1 - Device for attenuation correction of x-band single polarization radar reflectivity using adjacent multiple terrestrial microwave links and method therefor - Google Patents

Abstract

The present invention relates to an X-band single polarization radar reflectivity correction device and method, and particularly to an X-band single polarization radar reflectivity correction device and method using multiple terrestrial communication base station microwaves. The X-band single polarization radar reflectivity correction device and method using a multi-terrestrial communication base station microwave according to the present invention can determine the optimal attenuation correction coefficient that can take into account the spatial and temporal variations of rainfall. In addition, the There is an advantage.

Description

X-band single polarization radar reflectivity correction device and method using multiple terrestrial communication base station microwaves {DEVICE FOR ATTENUATION CORRECTION OF

The present invention relates to an X-band single polarization radar reflectivity correction device and method, and particularly to an X-band single polarization radar reflectivity correction device and method using multiple terrestrial communication base station microwaves.

Radar (Radio Detection And Ranging, RADAR) was initially used for military purposes, but has been used in various fields such as hydrology and meteorology since World War II. Weather radar is a remote observation equipment that transmits electromagnetic waves and receives electromagnetic waves that hit the target (precipitation particles) and return after being backscattered, and measures the distance to the target (precipitation particles) and the intensity of the precipitation particles. High-output large S-band and C-band radars have a spatial resolution of more than 1 km and a temporal resolution of 5 to 10 minutes at an observation radius of more than 200 km, so there are technical limitations in low-altitude and precise rainfall observation with high spatial and temporal resolution. there is. In contrast, the small It is effective for observing localized heavy rain in the area. The U.S. Collaborative Adaptive Sensing of the Atmosphere-Engineering Research Center (CASA-ERC), established in September 2003 with support from the National Science Foundation, uses several small The Japanese Disaster Prevention Science and Technology Research Institute has established a successful urban flood warning system by building several X-band radar networks since 2006. However, the X-band radar reflectivity with a short wavelength (3cm) is greatly attenuated by strong precipitation echoes, making it impossible to detect precipitation echoes behind the azimuth of the precipitation, so the reflectivity size must be corrected. An attenuation correction algorithm is being developed with the introduction of the We propose a new method to correct reflectivity attenuation of band single-polarized radar.

Republic of Korea Patent Publication No. 10-1291980 (registered on July 25, 2013)

The purpose of the present invention is to provide a correction device and method for correcting single-polarization X-band radar reflectivity, which has large radio wave attenuation due to precipitation.

The object of the present invention is not limited to the object mentioned above, and other objects and advantages of the present invention that are not mentioned can be understood through the following description and will be more clearly understood by the examples of the present invention. Additionally, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof indicated in the patent claims.

The X-band single polarization radar reflectivity correction device using a multi-terrestrial communication base station microwave according to the present invention collects the transmission power and reception power of the microwave link, and at least one Korea Meteorological Administration automatic weather observation equipment installed around the microwave link ( An observation data collection module that collects the rainfall time recorded in the rainfall detector of the Automatic Weather System (AWS) and the accumulated rainfall and rainfall time data recorded in the rain gauge, and microwave attenuation is performed using the difference between the transmitted power and received power of the microwave link. A microwave attenuation calculation module that calculates, a rainfall detection module that detects the presence or absence of rainfall based on the autocorrelation coefficient of microwave attenuation, and an attenuation size ( ) and the radar reflectivity of the X-band radar ( Attenuation-corrected radar reflectivity calculated using ) ( ) and includes a reflectivity correction module having an X-band radar reflectivity correction module that corrects the X-band radar reflectivity.

In addition, in the The above steps include collecting accumulated rainfall data and rainfall time data recorded at regular intervals in the rain detector and rain gauge of the Korea Meteorological Administration's Automatic Weather System (AWS), and measuring the transmission power and reception power of the microwave link. A microwave attenuation calculation module calculates microwave attenuation using the difference, a rainfall detection module detects the presence or absence of rainfall based on the autocorrelation coefficient of microwave attenuation, and a reflectivity correction module determines a cost function to determine the attenuation correction coefficient. Calculate the radar reflectivity and reflectivity X-band radar attenuation size for each gate (r) calculated by applying attenuation correction coefficients a and b Radar reflectance corrected for attenuation with It includes the step of calculating and correcting the X-band radar reflectivity.

Here, the attenuation corrected radar reflectivity ( )Is, and is the X-band radar attenuation magnitude, ego, is the attenuation value of the first gate of the X-band radar. The value of is 0, N is the total number of X-band radar gate data, is the gate spacing (km) of the X-band radar, and a and b are the attenuation correction coefficients of the X-band radar.

The X-band single polarization radar reflectivity correction device and method using a multi-terrestrial communication base station microwave according to the present invention can determine the optimal attenuation correction coefficient that can take into account the spatial and temporal variations of rainfall.

In addition, the There is an advantage.

In addition to the above-described effects, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

Figure 1 is a conceptual diagram of an X-band single polarization radar reflectivity correction device using microwaves from a multi-terrestrial communication base station according to the present invention.
Figure 2 is a diagram showing the variability of the attenuation correction coefficient for each microwave link in the case of convective clouds.
Figure 3 is a diagram showing the variability of the attenuation correction coefficient for each microwave link in the stratiform cloud case.
Figure 4 shows the calculation of the attenuation size for each gate by applying the average, maximum, minimum, and median values of the attenuation correction coefficients calculated from the microwave link, and then using this to correct the X-band radar reflectivity and verify it by comparing it with the S-band radar reflectivity. This is a diagram showing the results statistically.
Figure 5 shows the X-band radar reflectivity (Plan Position Indicator, PPI) before attenuation correction of the Korea Institute of Civil Engineering and Building Technology in the case of convection clouds at 7 o'clock on July 5, 2016.
Figure 6 shows the Korea Meteorological Administration's S-band radar reflectivity (PPI).
Figure 7 shows the
Figure 8 shows the calculated attenuation size for each X-band radar gate. This shows the X-band radar reflectivity corrected for attenuation by applying Equation 10.
Figure 9 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction at the AWS location operated by the Korea Meteorological Administration in Seoul.
Figure 10 shows a scatter plot between the attenuation corrected X-band radar reflectivity and S-band radar reflectivity.
Figure 11 shows the X-band radar reflectivity (PPI) before attenuation correction of the Korea Institute of Civil Engineering and Building Technology at 22:00 on May 2, 2016, a case of stratiform clouds.
Figure 12 shows the Korea Meteorological Administration's S-band radar reflectivity (PPI).
Figure 13 shows the X-band radar attenuation field calculated by applying the optimal attenuation correction coefficient calculated by applying the attenuation of seven microwave links from Equation 1 to Equation 9 to Equation 6.
Figure 14 shows the calculated attenuation size for each X-band radar gate. This shows the X-band radar reflectivity corrected for attenuation by applying Equation 10.
Figure 15 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction at the AWS location.
Figure 16 shows a scatter plot between the attenuation corrected X-band radar reflectivity and S-band radar reflectivity.
Figure 17 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction in the case of convective clouds on July 5, 2016.
Figure 18 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity after attenuation correction.
Figure 19 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction in the case of stratiform clouds on May 2, 2016.
Figure 20 shows a scatter plot between the X-band radar reflectivity and the S-band radar reflectivity after attenuation correction.
Figure 21 is a flowchart of X-band single polarization radar reflectivity correction using multiple terrestrial communication base station microwaves according to the present invention.

The above-mentioned objects, features, and advantages will be described in detail later with reference to the attached drawings, so that those skilled in the art will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, identical reference numerals are used to indicate identical or similar components.

Figure 1 is a conceptual diagram of an X-band single polarization radar reflectivity correction device using microwaves from a multi-terrestrial communication base station according to the present invention.

As shown in Figure 1, the Thus, microwave attenuation (Rain-caused attenuation, ), a microwave attenuation calculation module 200 that calculates, a rain presence detection module 300 that detects the presence or absence of rain based on microwave attenuation data, and a reflectivity correction module 400 that corrects the reflectivity of the X-band radar with an attenuation correction coefficient. Includes.

Table 1 shows the characteristics of the seven microwave links to be input to the observation data collection module according to the present invention and the name of the Automatic Weather Station (AWS) point installed closest to the receiving antenna of each microwave link.

Link
name Nearest
AWS Frequency
(GHz) Power
(dBm) Link Length (km) Signal resolution Time resolution HG 419 8.06 29 21.1 0.01 dBm 15 seconds GH 413 7.75 29 21.1 WM 401 6.32 29 5.7 MW 401 6.06 29 5.7 MH 401 8.26 30 17.6 H.M. 421 7.95 30 17.6 MB 425 6.23 30 37.4

The present invention collects the transmission power and reception power of 7 microwave links at 15 second intervals with a resolution of 0.01 dB, and uses microwaves of 6 to 8 GHz or less as a reference value for X-band radar reflectivity correction.

Table 2 shows the characteristics of the Korea Institute of Civil Engineering and Building Technology's X-band dual-polarization radar and the Korea Meteorological Administration's S-band single-polarization radar.

Parameters KICT radar GDK radar Location 37.67°N, 126.74°E 38.1173°N, 127.4336°E Transmitter type Magnetron Klystron Antenna Diameter 1.8m 8.5m Frequency 9410±30 MHz 2887 MHz Peak power 8kW 850kW Pulse width 0.6 μsec 0.8 μsec & 4.5 μsec Pulse repetition frequency 2000 Hz 250 to 1200 Hz Gain 41dB 45dB Time resolution 1 min 10min Spatial resolution 60m 250m Antenna polarization Simultaneous H/V Simultaneous H Effective observation range 40 km 240km Beam width 1.4° 1°

The observation data collection module 100 receives and collects observation data for X-band radar reflectivity correction. Here, the observation data collected by the observation data collection module 100 are the transmission power and reception power of the microwave link, and the rainfall time recorded in the rainfall detector of the Korea Meteorological Administration's Automatic Weather System (AWS) installed around the microwave link. It includes the accumulated rainfall and rainfall time data recorded in the rain gauge, the reflectivity of the X-band radar, and the reflectivity of the S-band radar. In addition, in order to collect this, the observation data collection module 100 includes a microwave link data collection module that collects the transmission power and reception power of the microwave link, and the rainfall recorded in the rainfall detector of the Korea Meteorological Administration's automatic weather observation equipment installed around the microwave link. A rainfall detector data collection module that collects duration data, an X-band radar data collection module that collects reflectivity from the Korea Institute of Civil Engineering and Building Technology's Includes.

The microwave attenuation calculation module 200 calculates microwave attenuation (rainfall-caused attenuation) using the difference between the transmitted power and received power of the microwave link. )

Calculate . Here, the microwave attenuation calculation module 200 calculates the microwave attenuation using the difference between the transmitted power and received power of the microwave link with 15 second resolution.

The presence or absence of rainfall detection module 300 detects the presence or absence of rainfall based on microwave attenuation data. To this end, the rainfall presence/absence detection module 300 includes a window size calculation module 310 that determines the minimum delay time at which the autocorrelation coefficient of microwave attenuation according to rainfall characteristics is 0.65 or more as the window size (moving time window, Wt); , the average microwave attenuation during the determined window size ( ), the average microwave attenuation calculation module 320, which calculates the microwave attenuation and the average microwave attenuation during the determined window size ( ), a test statistic calculation module 330 for microwave attenuation that calculates the test statistic of microwave attenuation using the difference between ), and a threshold value that determines the threshold value necessary to primarily determine the presence or absence of rainfall using microwave attenuation. Calculation module, primary rainfall detection module 350, which primarily detects the presence or absence of rainfall through the exceedance between the test statistic of microwave attenuation and a threshold value, the primarily determined rainfall presence or absence detection result and the average microwave during a specific window size attenuation( ), a microwave reference attenuation calculation module 360 that calculates the microwave reference attenuation (Ad) in real time, and a secondary rainfall detection module ( 370).

The window size calculation module 310 determines the minimum delay time at which the autocorrelation coefficient of microwave attenuation is statistically significant, for example, 0.65, based on the microwave attenuation data calculated by the microwave attenuation calculation module 200, to determine the window size. (moving time window, Wt).

Here, the autocorrelation coefficient is as shown in Equation 1 below.

In equation 1, ego represents the delay time.

The average microwave attenuation calculation module 320 averages the microwave attenuation during the window size determined in the window size calculation module 310 to calculate the average microwave attenuation ( ) is calculated.

Here, the average microwave attenuation ( ) is the average of the microwave attenuation size within the window size (Wt), and is expressed in Equation 2 below.

In equation 2, is the microwave attenuation magnitude measured in real time, is the number of microwave attenuation data within the window size (Wt).

The test statistic calculation module 330 for microwave attenuation calculates the microwave attenuation calculated in the microwave attenuation calculation module 200 ( ), and the average microwave attenuation calculated in the average microwave attenuation calculation module 320 ( ) is used to calculate the test statistic of microwave attenuation. Here, the test statistic of microwave attenuation ( ) is equivalent to Equation 3 below.

In Equation 3, since microwave attenuation is nonstationary, the test statistic of microwave attenuation ( ) and the standard deviation of microwave attenuation do not converge. is the average of the microwave attenuation within the window size (Wt).

The threshold calculation module 340 calculates the threshold value ( ) is calculated. In this embodiment, the final threshold ( ), which illustrates that it is 0.09.

The primary rainfall detection module 350 detects the test statistic of microwave attenuation ( ) and the threshold value calculated by the threshold calculation module 340. The presence or absence of rainfall is initially detected. That is, once the window size (Wt) is determined, the threshold ( ) is determined, and the presence or absence of rainfall using microwave attenuation, that is, the presence or absence of primary rainfall, is determined primarily by Equation 4 below.

The microwave reference attenuation calculation module 360 is the average microwave attenuation calculated by the average microwave attenuation calculation module 320 ( ), and the microwave reference attenuation (Ad) is calculated in real time using the primary rainfall detection result detected by the primary rainfall detection module 350. Here, the microwave reference attenuation (Ad) is calculated as Equation 5 below.

It is determined to be caused by rainfall when the magnitude of microwave attenuation exceeds the microwave reference attenuation (Ad) calculated in real time. The presence or absence of rainfall is finally determined secondarily by correcting the result of the presence or absence of rainfall determined primarily according to whether there is an excess between the microwave attenuation and the microwave reference attenuation (Ad). The microwave attenuation calculation module 200 caused by rainfall is the microwave attenuation calculated in the microwave attenuation calculation module 200 ( ) is the microwave reference attenuation calculated in the microwave reference attenuation calculation module 360 ( ) is the microwave attenuation magnitude ( Microwave attenuation caused by rainfall when greater than 2.5% of ) ( ) is decided.

The secondary rainfall detection module 370 detects microwave attenuation ( ) and the microwave reference attenuation (Ad). The presence or absence of secondary rainfall is detected by correcting the primary rainfall detection result determined through the exceedance. Here, the microwave reference attenuation (Ad) is the average of the microwave attenuation within the window size, and the microwave attenuation that differs significantly from the microwave reference attenuation within the window size ( ) is microwave attenuation when it rains ( ) is used to determine. Finally, microwave attenuation ( ) is used to determine the presence or absence of rainfall. In addition, this is verified by comparing it with the time data recorded as rainfall in the rainfall detector of the Automatic Weather Station (AWS) installed closest to the microwave link transmitting and receiving antenna.

The reflectivity correction module 400 calculates an attenuation correction coefficient to correct the reflectivity of the X-band radar. To this end, the reflectivity correction module 400 includes a microwave attenuation determination module 410 and an attenuation size for each X-band radar gate (r) ( ), an attenuation size calculation module 420 for each X-band radar gate, and an X-band radar average attenuation size ( ) X-band radar average attenuation magnitude calculation module 430, microwave attenuation magnitude converted to radar frequency ( ), a microwave attenuation k size calculation module 440 that calculates the cost function ( ) includes a cost function calculation module 450 that calculates, and an X-band radar reflectivity correction module 460 that corrects the X-band radar reflectivity. The microwave attenuation determination module 410 determines the microwave attenuation (Ad) exceeding the microwave reference attenuation (Ad). ) to the microwave attenuation caused by rainfall ( ) is decided.

The attenuation size calculation module 420 for each X-band radar gate determines the attenuation size for each X-band radar gate (r). ) is calculated. Here, the attenuation size for each X-band radar gate is expressed in Equation 6 below.

In equation 6, is the measured reflectivity data of the X-band radar, is the first gate of the radar, the attenuation value of the first gate of the radar The value of is 0. N is the total number of radar gate data. is the gate interval of the radar (km), and was multiplied by 2 to consider the round-trip distance of the radar electromagnetic wave. a, b are radar attenuation correction coefficients determined empirically. In this example, a is fluctuates within the range, and b is For example, it is a range. The radar azimuth closest to each microwave link was selected, and the microwave link was assumed to be on the line of that radar azimuth.

In order to determine the optimized a and b coefficients, the X-band radar average attenuation size calculation module 430 calculates the X-band radar average attenuation size ( ) is calculated. The coefficients a and b are initial values, and a is And b is used as a constant of 0.7.

In equation 7, is the total number of nearest radar gates corresponding to the path length of the microwave link.

The microwave attenuation size calculation module 440 is a microwave attenuation size converted to radar frequency ( ) is calculated. If the frequency of the microwave link and the X-band radar frequency are different, the attenuation size of the microwave link ( is multiplied by the ratio of the microwave link frequency and the X-band radar frequency to obtain the microwave attenuation magnitude ( ) is converted as shown in Equation 8 below and used as a reference value to determine the radar attenuation correction coefficient a.

The cost function calculation module 450 is the average attenuation size of the X-band radar ( ) and the converted microwave attenuation magnitude ( ) is calculated to calculate the difference between the cost function ( ) is estimated.

The average attenuation magnitude of the X-band radar ( ) The coefficients a and b required in the calculation are initial values, and a is was set relatively large, and a was set to be relatively large. Calculation stability was achieved by decreasing the number of units. And b was used as a constant of 0.7, and the value of a when the value of the cost function was less than 0.25 was determined as the X-band radar attenuation correction coefficient value.

Figure 2 is a diagram showing the variability of the attenuation correction coefficient for each microwave link in the case of convective clouds, and Figure 3 is a diagram showing the variability of the attenuation correction coefficient for each microwave link in the case of stratiform clouds. In addition, Figure 4 calculates the attenuation size for each gate by applying the average, maximum, minimum, and median values of the attenuation correction coefficients calculated from the microwave link, then uses this to correct the X-band radar reflectivity and compares it with the S-band radar reflectivity. This is a diagram that statistically shows the verification results.

Referring to Figures 2 and 3, Figure 2 shows the attenuation correction coefficients (a1, a2, a3, a4) for each microwave link determined using Equation 1 to Equation 9 described above in the case of convective clouds and 3 stratiform clouds. , a5, a6, a7). The attenuation correction coefficients for most microwave links ranged from 0 to 0.04 or less, but microwave links 6 and 7 showed relatively large changes due to the relatively short link length and the horizontal distance between the two microwave links and the X-band radar. Because it was relatively farthest. Figure 4 calculates the attenuation size for each gate by applying the average, maximum, minimum, and median values of the attenuation correction coefficients calculated from each microwave link, then uses this to correct the X-band radar reflectivity and compares it with the S-band radar reflectivity. This is a statistical representation of the verified results.

The X-band radar reflectivity correction module 460 is a radar reflectivity correction module. X-band radar attenuation size for each gate (r) calculated by applying attenuation correction coefficients a and b Use to correct the X-band radar reflectivity. This is the radar reflectivity corrected for attenuation as shown in Equation 10 below: It can be performed by calculating .

Figure 5 shows the X-band radar reflectivity (Plan Position Indicator, PPI) before attenuation correction of the Korea Institute of Civil Engineering and Building Technology in the case of convection clouds at 7 o'clock on July 5, 2016. Figure 6 shows the Korea Meteorological Administration's S-band radar reflectivity (PPI). Figure 7 shows the Figure 8 shows the calculated attenuation size for each X-band radar gate. This shows the X-band radar reflectivity corrected for attenuation by applying Equation 10. Figure 9 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction at the AWS location operated by the Korea Meteorological Administration in Seoul. Figure 10 shows a scatter plot between the attenuation corrected X-band radar reflectivity and S-band radar reflectivity. Figure 5 shows the X-band radar reflectivity (Plan Position Indicator, PPI) before attenuation correction of the Korea Institute of Civil Engineering and Building Technology in the case of convection clouds at 7 o'clock on July 5, 2016. Compared to the stratiform cloud case, the reflectivity of local rainfall cells was more than 40 dBZ. Figure 6 shows the Korea Meteorological Administration's S-band radar reflectivity (PPI). Figure 7 shows the Figure 8 shows the calculated attenuation size for each X-band radar gate. This shows the X-band radar reflectivity corrected for attenuation by applying Equation 10. After attenuation correction, it can be seen that the S-band radar reflectivity and spatial distribution are quite consistent. Figure 9 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction at the AWS location operated by the Korea Meteorological Administration in Seoul. The Mean Absolute Error (MAE) was 16.2 dB, RMSE was 17.7 dB, and the correlation coefficient was 0.7, indicating that the measurement was underestimated due to rainfall attenuation compared to the S-band radar reflectivity. Figure 10 shows the scatter plot between the attenuation corrected It was confirmed that it increased.

Figure 11 shows the Korea Institute of Civil Engineering and Building Technology's . Figure 13 shows the X-band radar attenuation field calculated by applying the optimal attenuation correction coefficient calculated by applying the attenuation of seven microwave links from Equation 1 to Equation 9 to Equation 6. Figure 14 shows the calculated attenuation size for each X-band radar gate. This shows the X-band radar reflectivity corrected for attenuation by applying Equation 10. Figure 15 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction at the AWS location. Figure 16 shows a scatter plot between the attenuation corrected X-band radar reflectivity and S-band radar reflectivity.

Figure 11 shows the X-band radar reflectivity (PPI) before attenuation correction of the Korea Institute of Civil Engineering and Building Technology at 22:00 on May 2, 2016, a case of stratiform clouds. Figure 12 shows the Korea Meteorological Administration's S-band radar reflectivity (PPI). Since the S-band radar electromagnetic waves are not greatly attenuated by precipitation, it can be seen that their size is relatively large compared to the X-band radar reflectivity. Figure 13 shows the X-band radar attenuation field calculated by applying the optimal attenuation correction coefficient calculated by applying the attenuation of seven microwave links from Equation 1 to Equation 9 to Equation 6. Figure 14 shows the calculated attenuation size for each X-band radar gate. This shows the X-band radar reflectivity corrected for attenuation by applying Equation 10. After attenuation correction, it can be seen that the S-band radar reflectivity and spatial distribution are quite consistent. Figure 15 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction at the AWS location. The absolute average error was 8.9 dB, RMSE was 10.3 Db, and the correlation coefficient was 0.3, indicating that it was underestimated. Figure 16 shows the scatter plot between the attenuation corrected did.

Figure 17 shows a scatter plot between the It is shown. Figure 19 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction in the case of stratiform clouds on May 2, 2016. Figure 20 shows a scatter plot between the X-band radar reflectivity and the S-band radar reflectivity after attenuation correction.

Figure 17 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction in the case of convective clouds on July 5, 2016. The black symbol shows the scatter between reflectivities in AWS located within a 10 km radius from the center of the It shows the scatter plot between reflectances. The absolute average error between the Figure 18 shows a scatter plot between the X-band radar reflectivity and the S-band radar reflectivity after attenuation correction. It can be seen that after attenuation correction, the absolute error between the Figure 19 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity before attenuation correction in the case of stratiform clouds on May 2, 2016. The absolute average error between the X-band radar and S-band radar reflectivities before attenuation correction was 6.4 dB, RMSE was 8.1 dB, and the correlation coefficient was 0.6. Figure 20 shows a scatter plot between the X-band radar reflectivity and S-band radar reflectivity after attenuation correction. The absolute average error between the X-band radar and S-band radar reflectivity after attenuation correction decreased from 6.4 dB before attenuation correction to 6.3 dB, and the RMSE decreased from 8.1 dB to 7.9 dB. It can be seen that the attenuation correction effect is greater in the convective cloud case than in the stratiform cloud case.

Next, the attenuation-corrected X-band radar reflectivity was verified using the

In order to verify the attenuation-corrected First, because the difference in horizontal distance between the two radars is hundreds of kilometers, a difference in beam height occurs due to the effect of the Earth's curvature. Therefore, in the present invention, the beam difference in the X-band radar elevation angle (5°) was minimized by adjusting the S-band radar elevation angle (0 to 1.7°) as shown in Table 3.

AWS
Site KICT
RBH (km) G.D.K.
RBH (km)/Elevation angle (°) AWS
Site KICT
RBH (km) G.D.K.
RBH (km)/Elevation angle (°) 116 2.8 2.7/1.0 411 2.0 2.2/0.6 400 2.9 2.6/1.0 413 2.9 2.6/1.0 401 2.9 2.8/1.0 414 2.1 2.0/0.6 402 3.4 3.3/1.7 415 2.4 2.2/0.6 403 3.2 3.5/1.7 416 1.6 1.5/0.2 404 1.5 1.4/0.0 417 2.4 2.3/0.6 405 1.9 1.9/0.3 418 2.2 2.3/0.6 406 2.2 2.3/1.0 419 2.2 2.1/0.6 407 2.8 3.1/1.7 421 2.7 2.6/1.0 408 2.6 2.5/1.0 423 2.0 1.9/0.3 409 2.9 3.2/1.7 424 1.9 1.9/0.6 410 2.3 2.3/0.6 425 2.9 2.8/1.0 506 0.9 1.3/0.0 509 2.6 2.7/1.0 510 1.9 1.8/0.3 532 2.3 2.1/1.0 540 1.2 1.3/0.0 541 3.3 2.9/1.7 544 1.9 2.0/0.3 569 3.2 3.1/1.7 572 3.5 3.7/1.7 589 0.3 1.4/0.0 590 3.2 2.9/1.0 599 3.4 2.4/1.7

The wavelength of the similar. When observed with a weather radar with a radio wave wavelength of several centimeters, Rayleigh scattering occurs in raindrops with a diameter of several millimeters, and Rayleigh scattering or Mie scattering occurs in snowflakes or hail with a diameter of several millimeters to several centimeters. S-band radar reflectivity was converted to X-band radar reflectivity using Equation 11 below.

In equation 11, is the S-band radar reflectivity, is the S-band radar reflectivity converted to X-band radar wavelength. When the S-band radar reflectivity is less than 25dBZ The reflectivity was converted by applying the equation, and when the S-band radar reflectivity is between 25dBZ and 45dBZ, The formula was applied, and if it is above 45dBZ, The conversion was performed by applying the formula.

The height difference of the radar beam and the wavelength difference between the X-band and S-band radars were considered, and other differences were assumed to be negligible. Quantitative verification was performed statistically using the formula below.

In the present invention, we proposed a method of using all seven microwave link attenuation data located within the radar radius to determine the optimal X-band radar attenuation correction coefficient a considering the spatiotemporal variability of rainfall. The average attenuation magnitude of the X-band radar due to rainfall corresponding to each microwave link path length ( , , , , , , 7 microwave link attenuation converted to X-band radar frequency ( ) and each cost function ( ) is the minimum ( The attenuation correction coefficients (a1, a2, a3, a4, a5, a6, a7) when 0.25) were calculated respectively. In the stratiform cloud rainfall case with little spatial and temporal variability, the average value of the seven attenuation correction coefficients was used, and in the convective cloud case, the maximum value of the seven attenuation correction coefficients was determined as the optimal attenuation correction coefficient. The present invention has the advantage of being able to determine the optimal attenuation correction coefficient that can take into account spatiotemporal variations in rainfall, and to stably calculate the attenuation correction coefficient even when a specific microwave link cannot provide attenuation data due to mechanical reasons. .

Next, an X-band single polarization radar reflectivity correction method using a multi-terrestrial communication base station microwave according to the present invention will be described with reference to the drawings. Each step of the X-band single polarization radar reflectivity correction method using multiple terrestrial communication base station microwaves according to the present invention, which will be described later, uses the X-band single polarization radar reflectivity correction device using the above-described multiple terrestrial communication base station microwaves.

Figure 21 is a flowchart of the X-band single polarization radar reflectivity correction method using microwaves from a multi-terrestrial communication base station according to the present invention.

Referring to Figure 21, the It includes a detection step (S2, not shown) and a step of correcting the reflectivity of the X-band radar (S3).

The observation data collection step (S1) is an observation data collection module that collects observation data for X-band radar reflectivity correction. Here, the observation data collected in the observation data collection step (S1) is the transmission power and reception power of the microwave link, and the rainfall detector of the Korea Meteorological Administration's Automatic Weather System (AWS) installed around the microwave link. It includes rainfall time, accumulated rainfall and rainfall time data recorded in the rain gauge, reflectivity of X-band radar, and reflectivity of S-band radar.

In the step (S2) of detecting the presence or absence of rainfall based on microwave attenuation data, the rainfall presence detection module detects the presence or absence of rainfall based on the microwave attenuation data.

The step (S3) of correcting the reflectivity of the X-band radar determines the cost function, calculates the attenuation correction coefficient, and calculates the radar reflectivity X-band radar attenuation size for each gate (r) calculated by applying attenuation correction coefficients a and b Radar reflectance corrected for attenuation with Calculate the X-band radar reflectivity. The step of correcting the reflectivity of the X-band radar (S3) includes the step of determining the cost function (S3-1) and the radar reflectivity It includes a step (S3-2) of calculating and correcting the X-band radar reflectivity.

The step of determining the cost function (S3-1) calculates the cost function based on the observation data collected in the step of collecting observation data (S1), and determines whether the calculated cost function is the minimum. To this end, the step of determining the cost function (S3-1) includes calculating the attenuation size for each X-band radar gate (S3-1-1), and calculating the microwave attenuation caused by rainfall using link characteristics. Step (S3-1-2), calculating the microwave attenuation magnitude (S3-1-3), calculating the X-band radar average attenuation magnitude (S3-1-4), and calculating the cost function ( S3-1-5).

The step (S3-1-1) of calculating the attenuation size for each X-band radar gate is performed by the attenuation size calculation module for each X-band radar gate (r). ) is calculated. Here, the attenuation size for each X-band radar gate (r) ( ) is the same as Equation 6 described above.

In the step (S3-1-2) of calculating the microwave attenuation caused by rainfall using link characteristics, the microwave attenuation calculation module calculates microwave attenuation (rainfall-caused attenuation) using the difference between the transmitted power and received power of the microwave link. ) is calculated.

The step of calculating the microwave attenuation magnitude (S3-1-3) is the microwave attenuation magnitude calculation module converting the microwave attenuation magnitude to the radar frequency ( ) is calculated. This can be obtained as in Equation 8 described above.

In the step (S3-1-4) of calculating the X-band radar average attenuation size, the X-band radar average attenuation size calculation module calculates the X-band radar average attenuation size ( ) is calculated.

In the step of calculating the cost function (S3-1-4), the cost function calculation module calculates the average attenuation size of the X-band radar ( ) and the converted microwave attenuation magnitude ( ) by calculating the difference between the cost function ( ) is estimated.

radar reflectivity The step (S3-2) of calculating and correcting the X-band radar reflectivity is the radar reflectivity. Calculate the X-band radar reflectivity. For this purpose, the radar reflectivity The step of calculating the X-band radar reflectivity (S3-2) includes calculating the attenuation correction coefficient (S3-2-1), selecting the attenuation correction coefficient (S3-2-2), and the reflectivity It includes a step of correcting (S3-2-3).

The step of calculating the attenuation correction coefficient (S3-2-1) is the microwave link attenuation obtained by converting the average attenuation size of the seven X-band radars due to rainfall corresponding to the microwave link path length into the seven X-band radar frequencies and each Calculate the attenuation correction coefficient when the cost function becomes minimum. Of course, this embodiment illustrates the average attenuation size of seven X-band radars because the characteristics of seven microwave links are input to the observation data collection module, and this may vary depending on the number of characteristics of the microwave links input to the observation data collection module You can.

In the step of selecting the attenuation correction coefficient (S3-2-2), among the attenuation correction coefficients calculated in the step of calculating the attenuation correction coefficient (S3-2-1), in the case of stratiform cloud rainfall with little spatial and temporal variability, 7 attenuation The average value of the correction coefficients is selected, and in the case of convective clouds, the maximum value of the seven attenuation correction coefficients is selected as the optimal attenuation correction coefficient.

In the step of correcting reflectivity (S3-2-3), the X-band radar reflectivity correction module X-band radar attenuation size for each gate (r) calculated by applying attenuation correction coefficients a and b Using the attenuation-corrected radar reflectivity as shown in Equation 10 above, Calculate the X-band radar reflectivity.

As described above, the present invention has been described with reference to the illustrative drawings, but the present invention is not limited to the embodiments and drawings disclosed herein, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. It is obvious that transformation can occur. In addition, although the operational effects according to the configuration of the present invention were not explicitly described and explained while explaining the embodiments of the present invention above, it is natural that the predictable effects due to the configuration should also be recognized. In other words, the present invention may be applied to various situations other than the medical request situation described above, such as area search, map service, construction of base data for a specific area, etc. Additionally, the above-described control method may be implemented as a program and stored in a storage medium.

100: Observation data collection module
200: microwave attenuation output module
300: Rainfall detection module
310: window size calculation module
320: Average microwave attenuation calculation module
330: Microwave attenuation test statistic calculation module
340: Threshold calculation module
350: Primary rainfall presence/absence detection module
360: Microwave reference attenuation calculation module
370: Secondary rainfall presence/absence detection module
400: Reflectivity correction module
410: Microwave attenuation determination module
420: X-band radar gate-specific attenuation size calculation module
430: X-band radar average attenuation magnitude calculation module
440: Microwave attenuation magnitude calculation module
450: Cost function calculation module
460: X-band radar reflectivity correction module

Claims (4)

The transmitted power and received power of the microwave link are collected, and recorded at regular intervals in the rain detector and rain gauge of at least one Korea Meteorological Administration Automatic Weather System (AWS) installed around the microwave link. An observation data collection module that collects accumulated rainfall data and rainfall time data,
A microwave attenuation calculation module that calculates microwave attenuation using the difference between the transmitted power and received power of the microwave link,
A rainfall detection module that detects the presence or absence of rainfall based on the autocorrelation coefficient of the microwave attenuation, and
Attenuation size for each X-band radar gate (r) when detecting rainfall in the rainfall detection module ) and the radar reflectivity of the X-band radar ( Attenuation-corrected radar reflectivity calculated using ) ( ) and includes a reflectivity correction module having an X-band radar reflectivity correction module that corrects the X-band radar reflectivity,
The attenuation corrected radar reflectivity ( )Is,
and
remind is the X-band radar attenuation magnitude,
ego,
remind is the attenuation value of the first gate of the X-band radar. The value of is 0,
N is the total number of X-band radar gate data,
remind is the gate spacing (km) of the X-band radar,
Above, a and b are an X-band single polarization radar reflectivity correction device using a multi-terrestrial communication base station microwave, which is the attenuation correction coefficient of the X-band radar.
delete The observation data collection module collects the transmitted power and received power of the microwave link and sends them to the rain detector and rain gauge of at least one Korea Meteorological Administration Automatic Weather System (AWS) installed around the microwave link. Collecting accumulated rainfall data and rainfall time data recorded at regular intervals;
A microwave attenuation calculation module calculating microwave attenuation using the difference between the transmitted power and received power of the microwave link,
A rainfall detection module detects the presence or absence of rainfall based on the autocorrelation coefficient of the microwave attenuation, and
The reflectivity correction module determines the cost function and calculates the attenuation correction coefficient, and the radar reflectivity X-band radar attenuation size for each gate (r) calculated by applying attenuation correction coefficients a and b Radar reflectance corrected for attenuation with It includes the step of calculating and correcting the X-band radar reflectivity,
The attenuation corrected radar reflectivity ( )Is,
and
remind is the X-band radar attenuation magnitude,
ego,
remind is the attenuation value of the first gate of the X-band radar. The value of is 0,
N is the total number of X-band radar gate data,
remind is the gate spacing (km) of the X-band radar,
Above, a and b are the attenuation correction coefficients of the X-band radar.
delete