KR101636651B1 - Apparatus and method for estimation of hybrid surface rainfall based on radar - Google Patents

Abstract

Disclosed are an apparatus and a method for estimating hybrid elevation angle radar rainfall. According to the present invention, the method comprises: a step of generating a ground echo map with the minimum elevation angle, not influenced by a ground echo, by using a single polarization radar reflection material; a step of generating a beam shielding mask with the maximum elevation angle, not influenced by beam shielding; a step of generating a hybrid high elevation mask by combining the generated ground echo map with the beam shielding mask; and a step of estimating rainfall through the generated hybrid high elevation mask. Accordingly, the method minimizes an error caused by the ground echo and the beam shielding, thereby correctly estimating the rainfall.

Description

[0001] APPARATUS AND METHOD FOR ESTIMATION OF HYBRID SURFACE RAINFALL BASED ON RADAR [0002]

The present invention relates to an apparatus and method for estimating a hybrid altitude-specific radar rainfall, and more particularly, to an apparatus and method for estimating a hybrid altitude-specific radar rainfall, which can minimize errors caused in estimating a rainfall amount using a weather radar.

In general, radar beams observe importers floating in the air, so it is different from the actual precipitation on the ground. Therefore, when estimating the rainfall with the weather radar, it is necessary to use radar observation data as close as possible to the ground. However, the weather radar is more susceptible to contamination of weather radar data by terrain echoes and topographical echoes as the beam is closer to the ground, and from rainfall echoes due to insects or algae and bright bands.

Therefore, for accurate ground-based rainfall estimation using weather radar, it is important to use the nearest elevation angle to the ground without being contaminated by beam shielding, topography echoes and non-rainfall echoes.

Thus, a Hybrid Surface Rainfall (HSR) mask of a dual polarized radar using a beam shielding simulation and a topographic echo map is used so that the beam shielding by the terrain is avoided in the past, and it is not affected by the terrestrial echo and non-rainfall echo The research to generate has proceeded.

However, since the HSR mask of the conventional dual polarized radar is performed assuming the standard ambience as the beam shielding simulation, there is a limitation in discriminating the shielding caused by the artificial structure or the abnormal radio waves, and the reflectivity data on the day when the terrestrial echo map is clear , It is difficult to grasp the topographic echo distribution of rainfall day.

Therefore, to accurately estimate the rainfall using radar reflectivity data, HSR mask, which can compensate the limitation of terrestrial echo discrimination by using beam shielding simulation and topographic echo mapping, is required.

Korea Patent No. 1451548 Korea Patent No. 1221773

One aspect of the present invention is to generate a hybrid altitude angle mask by combining a topographic echo map that minimizes the effect of the terrain echo and a beam shielding mask that minimizes the beam shielding effect so as to perform accurate rainfall amount estimation, And a rainfall estimation unit for estimating rainfall through each of the masks.

The hybrid altitude radar rainfall estimating apparatus according to one aspect of the present invention includes a weather radar data collection unit for collecting weather radar reflectivity data and a weather radar data collection unit for collecting the weather radar reflectivity data, A topographic echo map generating unit for generating a topographic echo map composed of the minimum altitude angles at which the at least one altitude angle is lower than a predetermined altitude angle, and a meteorological shielding mask composed of the lowest altitude angle not affected by the beam shielding by using the meteorological radar reflectance data collected through the meteorological radar data collecting unit A hybrid altitude angle mask that combines the terrain echo map and the beam shielding mask to generate a hybrid altitude angle mask having a minimum altitude angle at which the beam shielded area and the terrain echo area are not present in each radar bin Each mask generation unit and the hybrid And a rainfall estimating unit that performs rainfall estimation through the altitude angle mask.

The meteorological radar reflectance data collected through the meteorological radar data collecting unit is statistically analyzed to determine a frequency of occlusion of reflectivity (FOR), mean reflectivity (MREF), relativity of mean (REF) And a characteristic variable calculating unit for calculating a characteristic variable including a vertical gradient of FOR (VFOR) and a vertical gradient of REFlectivity (VREF).

Wherein the terrain echo map generating unit compares a frequency of occlusion of reflectivity (FOR) and a mean reflexivity (MREF) calculated for each radar bin with a predetermined threshold value to calculate a frequency of occlusion of reflectivity (FOR) and a mean reflexivity (MREF) The altitude angle of the radar bin may be selected as the lowest altitude angle of the corresponding radar bin, and the terrain echo map may be generated at the selected altitude angle.

Wherein the terrain echo map generating unit compares a frequency of occlusion of reflectivity (FOR) and a mean reflexivity (MREF) calculated for each radar bin with a predetermined threshold value to calculate a frequency of occlusion of reflectivity (FOR) and a mean reflexivity (MREF) The altitude angle of the radar bin may be increased to select the lowest altitude angle, and the terrain echo map may be generated at the selected altitude angle.

The terrain echo map generation unit may increase the elevation angle of the corresponding radar bin to a higher elevation angle and recalculate the frequency of occlusion of reflectivity and mean reflexibility according to the increased elevation angle, (OF) and Mean Reflectivity (MREF) are compared with the preset threshold value to determine whether or not at least one of a Frequency of Occurrence of Reflectivity (FOR) and a Mean Reflectivity (MREF) (Frequency of Occurrence of Reflection) and MREF (Mean Reflectivity) are both equal to or less than the predetermined threshold value, the frequency elevation angle of Reflectivity (MREF) and Mean Reflectivity (MREF) is less than the preset threshold value, Can be selected.

The beam shield mask generation unit may calculate an integrated membership value capable of selecting a minimum altitude angle at which the beam shielding region does not exist using the characteristic variable, compare the calculated overall membership value with a predetermined threshold value, And generate the beam shielding mask at a selected elevation angle through a selected minimum altitude angle and beam shielding simulation.

Wherein the beam shield mask generation unit classifies a shielded area and a non-shielded area using the characteristic variable, calculates a normalized frequency distribution (NFD) of the characteristic variable for each of the shielded area and the non-shielded area, A membership value of a characteristic variable of the characteristic variable and a membership variable value of a characteristic variable of an MF are calculated by using a normalized frequency distribution and a weight of the characteristic variable and a characteristic parameter of an MF The total membership value can be calculated using the membership value of the shielded area.

The weight can be calculated using the normalized frequency distribution (NFD) of the characteristic variable in the shielding region and the width of the region in which the normalized frequency distribution (NFD) of the characteristic variable in the non-shielded region is superimposed. Can be calculated.

는 특성변수의 가중치를 나타내며,

는 i번째 특성변수에 대한 차폐 영역과 비차폐 영역의 NFD(Normalize Frequency Distribution) 값의 중첩 영역의 넓이를 의미하며, S는

로 나타내며, m은 사용한 특성변수의 개수를 의미한다.Here, i means the type of the characteristic variable,

Represents the weight of the characteristic variable,

Is the width of the overlap region of the NFD (Normalize Frequency Distribution) values of the shielded region and the non-shielded region for the i-th characteristic variable, and S

And m denotes the number of the used characteristic variables.

The membership value of each characteristic variable of the MF (Membership Function) is a sum of the Normalized Frequency Distribution (NFD) of the shielded region and the Normalized Frequency Distribution (NFD) of the non-shielded region at any value of the characteristic variable, Is defined as the ratio of the normalized frequency distribution (NFD) of the region, and can be calculated by the following equation.

는 MF(Membership Function)의 특성변수 별 차폐 영역 소속값(Membership value)을 나타내며, p는 특성변수의 임의의 값을 의미하며,

는 차폐 영역에 해당하는 임의의 레이더 빈 위치에서 i번째 특성변수의 NFD(Normalize Frequency Distribution)를 나타내고,

는 비차폐 영역에 해당하는 임의의 레이더 빈 위치에서 i번째 특성변수의 NFD(Normalize Frequency Distribution)를 나타낸다.here,

Denotes Membership value of the shielding zone for each characteristic variable of the MF (Membership Function), p denotes an arbitrary value of the characteristic variable,

Represents a normalized frequency distribution (NFD) of an i-th characteristic variable at an arbitrary radar bin corresponding to the shielded area,

Denotes the Normalized Frequency Distribution (NFD) of the i-th characteristic variable at an arbitrary radar bin corresponding to the non-shielded region.

The total membership value is defined as a sum of products obtained by multiplying the weights by the membership values of the characteristic variables of the MF (Membership Function), and can be calculated by the following equation.

은 종합 소속값을 나타내며,

는 특성변수의 가중치를 나타내며,

는 차폐 영역에 해당하는 임의의 레이더 빈 위치에서 i번째 특성변수에 대한 MF(Membership Function)의 소속값을 나타내며, p는 특성변수의 임의의 값을 의미한다.here,

Represents the total affiliation value,

Represents the weight of the characteristic variable,

Denotes the membership value of the membership function (MF) for the i-th characteristic variable at an arbitrary radar bin corresponding to the shielded area, and p denotes an arbitrary value of the characteristic variable.

Wherein the beam shield mask generation unit compares the integrated membership value with a preset threshold value and selects the altitude angle of the radar bin as the lowest altitude angle of the corresponding radar bin if the integrated membership value is less than the preset threshold value, If the total belonging value is greater than or equal to the preset threshold value, raising the altitude angle of the radar bin to a higher altitude angle, re-calculating the total belonging value according to the increased altitude angle, If the total affiliation value of the property is less than the preset threshold value, the altitude angle is increased to a minimum altitude angle of the corresponding radar bin, and if the integrated belonging value is not less than the predetermined threshold value The altitude angle is increased until the total belonging value becomes less than the preset threshold value, and the minimum altitude angle is selected .

According to an aspect of the present invention, there is provided a method for estimating a hybrid altitude radar rainfall using a weather radar data collection unit provided in a weather radar system, And the beam shield mask generator uses the collected weather radar reflectivity data to generate a beam shield mask composed of the lowest altitude angles not affected by beam shielding , A hybrid altitude angle mask generation unit combines the topographic echo map and the beam shield mask to generate a hybrid altitude angle mask composed of the optimal multiple altitude angles, and the rainfall estimator can perform rainfall estimation through the hybrid altitude angle mask .

The optimal multi-elevation angle may be the lowest altitude angle at which there is no both a beam-shielded area and a terrain echo area in each radar bin.

The generation of the terrain echo map is performed by statistically analyzing the collected weather radar reflectivity data to calculate a frequency of occlusion of reflectivity (FOR) and a mean reflexivity (MREF) for each radar bin, and calculating a frequency of occlusion of reflectivity (FOR) And MREF (Mean Reflectivity) to generate the terrain echo map.

The generation of the terrain echo map using the Frequency of Occurrence of Reflectivity (FOR) and the Mean Reflectivity (MREF) is performed by setting a frequency of occlusion of reflectivity (FOR) and mean reflectivity (MREF) And selecting an altitude angle of the radar bin as a minimum altitude angle of the corresponding radar bin if at least one of the frequency of occlusion of reflectivity (FOR) and the mean reflexivity (MREF) is less than the preset threshold value, The terrain echo map can be generated at the selected minimum altitude angle.

The generation of the terrain echo map using the Frequency of Occurrence of Reflectivity (FOR) and Mean Reflectivity (MREF) is performed by setting a frequency of occlusion of reflectivity (FOR) and an average reflectivity (MREF) If the frequency of occlusion of reflectivity (FOR) and mean reflexivity (MREF) are both equal to or greater than the predetermined threshold value, the altitude angle of the radar bin is increased to select the lowest altitude angle. The terrain echo map can be generated.

The generation of the terrain echo map using the Frequency of Occurrence of Reflectivity (FOR) and the MREF is performed by comparing a Frequency of Occurrence of Reflectivity (FOR) and an MREF (Mean Reflectivity) If the Frequency of Occurrence of Reflectivity (FOR) and the Mean Reflectivity (MREF) are both equal to or greater than the predetermined threshold value, the elevation angle of the corresponding radar bin is increased to select the lowest elevation angle, Lt; / RTI >

Selecting the minimum altitude angle by increasing the altitude of the corresponding radar bin increases the elevation angle of the corresponding radar bin to a higher elevation angle and increases the frequency of occlusion of reflectivity The frequency of occlusion of reflectivity (FOR) and the mean reflectivity (MREF) are compared with the predetermined threshold value to calculate a frequency of occlusion of reflectivity (FOR) and an MREF (REF) and Mean Reflectivity (MREF) are both selected as the minimum altitude angles of the corresponding radar bin when at least one of the mean and the mean REFlectivity is less than the preset threshold value, If at least one of the Frequency of Occurrence of Reflectivity (FOR) and Mean Reflectivity (MREF) is less than the predetermined threshold value You can select the minimum altitude angle by increasing the altitude angle.

The generation of the beam shielding mask is performed by statistically analyzing the collected weather radar reflectivity data to calculate a characteristic variable for each radar bin and selecting a minimum altitude angle at which no beam shielding region exists using the characteristic variable The value of the affiliation value may be calculated, the calculated altitude value may be compared with a predetermined threshold value to select the lowest altitude angle, and the beam shielding mask may be generated at the selected altitude angle through the selected altitude angle and beam shielding simulation.

The characteristic variable includes a frequency of occlusion of reflectivity (FOR), a mean REFlectivity (MREF), a relative of FOR (RFOR), a relative gradient of RE (REF), a vertical gradient of FOR (VFOR) REFlectivity).

Calculating the total membership value is performed by classifying the shielded area and the non-shielded area using the characteristic variable and the non-shielding ratio in the beam shielding simulation, and determining the NFD of the characteristic variable according to the shielded area and the non- And calculates a membership value of a shadowed area for each characteristic parameter of the MF and a characteristic value of the characteristic variable using NFD (Normalized Frequency Distribution) of the characteristic variable, The total membership value can be calculated using the membership value of the shielding area for each characteristic variable of the weight and the membership function (MF).

The weight can be calculated using the normalized frequency distribution (NFD) of the characteristic variable in the shielding region and the width of the region in which the normalized frequency distribution (NFD) of the characteristic variable in the non-shielded region is superimposed. Can be calculated.

는 특성변수의 가중치를 나타내며,

는 i번째 특성변수에 대한 차폐 영역과 비차폐 영역의 NFD(Normalize Frequency Distribution) 값의 중첩 영역의 넓이를 의미하며, S는

로 나타내며, m은 사용한 특성변수의 개수를 의미한다.Here, i means the type of the characteristic variable,

Represents the weight of the characteristic variable,

Is the width of the overlap region of the NFD (Normalize Frequency Distribution) values of the shielded region and the non-shielded region for the i-th characteristic variable, and S

And m denotes the number of the used characteristic variables.

The membership value of the characteristic variable of the MF (Membership Function) is calculated by adding the sum of the Normalized Frequency Distribution (NFD) of the shielded region and the Normalized Frequency Distribution (NFD) of the non- Is defined as the ratio of the normalized frequency distribution (NFD) of the region, and can be calculated by the following equation.

는 MF(Membership Function)의 특성변수 별 차폐 영역 소속값(Membership value)을 나타내며, p는 특성변수의 임의의 값을 의미하며,

는 차폐 영역에 해당하는 임의의 레이더 빈 위치에서 i번째 특성변수의 NFD(Normalize Frequency Distribution)를 나타내고,

는 비차폐 영역에 해당하는 임의의 레이더 빈 위치에서 i번째 특성변수의 NFD(Normalize Frequency Distribution)를 나타낸다.here,

Denotes Membership value of the shielding zone for each characteristic variable of the MF (Membership Function), p denotes an arbitrary value of the characteristic variable,

Represents a normalized frequency distribution (NFD) of an i-th characteristic variable at an arbitrary radar bin corresponding to the shielded area,

Denotes the Normalized Frequency Distribution (NFD) of the i-th characteristic variable at an arbitrary radar bin corresponding to the non-shielded region.

The total membership value is defined as a sum of products of the weight and a membership value of the membership function (MF), and can be calculated by the following equation.

은 종합 소속값을 나타내며,

는 특성변수의 가중치를 나타내며,

는 차폐 영역에 해당하는 임의의 레이더 빈 위치에서 i번째 특성변수에 대한 MF(Membership Function)의 소속값을 나타내며, p는 특성변수의 임의의 값을 의미한다.here,

Represents the total affiliation value,

Represents the weight of the characteristic variable,

Denotes the membership value of the membership function (MF) for the i-th characteristic variable at an arbitrary radar bin corresponding to the shielded area, and p denotes an arbitrary value of the characteristic variable.

Comparing the total membership value with the predetermined threshold value to select the minimum altitude angle may be performed by comparing the total membership value with a predetermined threshold value and if the total affiliation value is less than the preset threshold value, The altitude angle of the corresponding radar bin is increased to a higher altitude angle by one step, and when the total belonging value is greater than or equal to the predetermined threshold value, the altitude angle of the radar bin is increased to a higher altitude angle, The altitude angle obtained by comparing the total affiliation value derived from the property with the predetermined threshold value and increasing the integrated belonging value when the total belonging value is less than the preset threshold value is selected as the minimum altitude angle of the corresponding radar bin, If the total belonging value of the property is equal to or greater than the preset threshold value, You can select the minimum elevation angle by increasing the elevation angle until you reach the limit.

According to an aspect of the present invention, it is possible to generate a rainfall map capable of minimizing the influence of the terrain echo and the beam shielding by discriminating the terrain echo area and the shielded area using the reflectivity statistics and the fuzzy logic, New rainfall maps can be used to estimate rainfall more accurately.

1 is a diagram illustrating an overall system of a hybrid altitude angular rainfall estimating apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing the distribution of the frequency of occlusion of reflectivity (FOR) at altitude angles of 0.0 ° and 0.4 °.
FIG. 3 is a graph showing the distribution of mean reflectivity (MREF) at altitudes of 0.0 ° and 0.4 °.
4 is a diagram showing the distribution of RFOR (Relative of FOR) at altitude angles of 0.0 ° and 0.4 °.
5 is a graph showing the distribution of RREF (relative of mean REFlectivity) at altitude angles of 0.0 ° and 0.4 °.
FIG. 6 is a diagram showing the distribution of a vertical gradient of FOR (VFOR) at altitude angles of 0.0 ° and 0.4 °.
Fig. 7 is a diagram showing the distribution of VREF (Vertical gradient of REFlectivity) at altitude angles of 0.0 ° and 0.4 °.
8 is a graph showing the distribution of the Gwanaksan radar unshielding rate at an altitude angle of 0.0 degrees calculated through beam shielding simulation.
Fig. 9 is a diagram showing the separation of the shielded area and the non-shielded area at altitude angles of 0.0 ° and 0.4 °.
FIGS. 10A and 10B are diagrams illustrating normalized frequency distribution (NFD) of characteristic parameters in a shielded area and a non-shielded area.
11A, 11B, and 11C are views showing a result of rainfall estimation verification using a hybrid altitude angle mask according to an embodiment of the present invention.
12 is a flowchart illustrating a method of estimating a hybrid altitude angle radar rainfall according to an embodiment of the present invention.
13 is a detailed flowchart showing a method of generating the terrain echo map shown in FIG.
14 is a detailed flowchart showing a method of generating the beam shield mask shown in FIG.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings. Embodiments of the present invention include a radar data analyzing unit for generating a rainfall map by analyzing summer single-polarity radar reflectivity data in which rainfall such as typhoons and concentrated rainfall are intensively generated for precise rainfall estimation, Will be described with reference to the drawings.

FIG. 1 is a view showing an overall system of a hybrid altitude angular rainfall estimating apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the frequency of occlusion of reflectivity at altitudes of 0.0 ° and 0.4 ° , And FIG. 3 is a graph showing the mean REFlectivity (MREF) at altitude angles of 0.0 ° and 0.4 °.

The hybrid altitude each radar rainfall estimating apparatus 200 according to an embodiment of the present invention uses a single polarized radar data to discriminate a terrain echo map and a beam shielding region that can discriminate a terrestrial echo region for more accurate rainfall estimation Combining the available beam shielding masks can produce a rainfall map composed of hybrid altitude angles. At this time, the terrain echo map may be composed of the lowest altitude angle that is not affected by the terrain echo, and the beam shield mask may be composed of the lowest altitude angle that is not affected by the beam shielding. The hybrid altitude each radar rainfall estimation apparatus 200 according to an embodiment of the present invention can perform rainfall estimation using the generated hybrid altitude angle mask. The apparatus for estimating the altitude and altitude of the radar rainfall according to an embodiment of the present invention includes a weather radar data collection unit 210, a characteristic variable calculation unit 220, a terrain echo map generation unit 230, A mask generation unit 240, a hybrid altitude angle mask generation unit 250, and a rainfall estimation unit 260.

The weather radar data collection unit 210 may collect the observed weather radar data from the weather radar system 100. At this time, the weather radar is a single polarized radar, and the observation data may be single polarization observation data, radar observation altitude angle information, and radar reflectivity data. At this time, the weather radar according to an embodiment of the present invention has 13 (0.0, 0.4, 0.8, 1.2, 1.6, 2.0, 3.0, 4.2, 5.7, 7.5, 9.8, °, 15.8 °), depending on the elevation angle.

The characteristic parameter calculating unit 220 may calculate characteristic parameters for discriminating the terrain echo area and the beam shielding area using the radar reflectivity data collected by the weather radar data collecting unit 210. [ In this case, the characteristic variables include a frequency of occlusion of reflectivity (FOR), mean reflectivity (MREF), relativity of FOR (RFOR), relativel of mean REFlectivity (RREF), vertical gradient of FOR (VFOR), vertical gradient of REFlectivity , Normalized Frequency Distribution (NFD), and Membership Function (MF).

First, the characteristic parameter calculator 220 can calculate FOR and MREF for each radar bin to analyze the single polarized radar reflectivity data to generate a rainfall map that is not affected by the terrain echo and beam shielding. FOR represents the reflectivity frequency distribution and can be calculated by the ratio of the cumulative total number of total reflection data and the cumulative number of total reflection data over a predetermined threshold value as shown in Equation (1). At this time, the characteristic parameter calculating unit 220 according to an embodiment of the present invention applies a predetermined threshold value of 10 dBZ to calculate FOR.

Where i, j, and k denote the azimuth, radar bin, and altitude angles, respectively, where N is the total number of cumulative data and n is the reflectivity frequency above a predetermined threshold (eg, 10 dBZ). On the other hand, a lower value of FOR may mean that the corresponding radar bin is a potential shielding zone. If the FOR of any radar bin has a relatively higher value than the FOR of the surrounding radar bin, the corresponding radar bin may have a terrain or marine echo area . Referring to FIG. 2, since the FOR value in the north-north direction is lower than that in the other regions, the region in the north-north direction can be analyzed as a shielded region, and a low FOR is observed at an azimuth angle of 37 ° and 76 °. And 76 deg. Can be analyzed as a shielded area. Also, since FOR is higher than other areas within 100 km from the center of the radar, it can be analyzed that the area within 100 km from the radar center is a terrain echo area.

MREF denotes an average reflectivity distribution, and can be calculated as a ratio between the total number of reflectance data and the sum of reflectances on a predetermined value of the mute value as shown in Equation (2). At this time, the characteristic parameter calculating unit 220 according to the embodiment of the present invention applies a predetermined threshold value of 10 dBZ to calculate the MREF.

는 미리 정해진 문턱값(예를 들어, 10dBZ) 이상의 반사도를 나타내며 단위는

이며, N은 총 누적자료수를 의미한다. 한편, 임의의 레이더 빈의 MREF가 인접한 다른 레이더 빈의 MREF에 비해 상대적으로 낮게 나타나면 해당 레이더 빈이 차폐 영역임을 의미하며, 지형 에코 지역에서의 MREF는 강우유무에 관계없이 항상 강한 반사도가 존재하기 때문에, 임의의 레이더 빈의 MREF가 인접한 레이더 빈의 MREF에 비해 상대적으로 높게 나타나는 경우 해당 레이더 빈이 지형 에코 영역임을 의미할 수 있다. 도 3 을 참조하면, 정북방향에서의 MREF 값은 다른 영역에 비해 매우 낮게 나타나므로 정북방향의 영역을 차폐 영역인 것으로 분석할 수 있으며, 방위각 37°와 76°부근에서 MREF가 미리 정해진 문턱값(예를 들어, 10dBZ) 이하의 값으로 나타나는 것으로 보아 방위각 37°와 76°부근의 영역을 차폐 영역으로 분석할 수 있다.here,

Represents a reflectivity higher than a predetermined threshold value (for example, 10 dBZ), and the unit

And N is the total cumulative data. On the other hand, if the MREF of an arbitrary radar bin is relatively low compared to the MREF of another adjacent radar bin, it means that the corresponding radar bin is a shielded area. Since the MREF in the terrain echo area always has a strong reflectivity regardless of rainfall, If the MREF of an arbitrary radar bin is relatively high relative to the MREF of an adjacent radar bin, it may mean that the radar bin is a terrain echo area. Referring to FIG. 3, since the MREF value in the north-north direction is much lower than that in the other regions, it can be interpreted that the region in the north direction is the shielded region. In the vicinity of the azimuth angles of 37 ° and 76 °, the MREF has a predetermined threshold value (For example, 10 dBZ), it is possible to analyze the area around the azimuth angle of 37 ° and 76 ° as the shielded area.

Referring to FIGS. 2, 3 and 9, when comparing FIG. 2 and FIG. 9 with a partial shielding region indicated by a yellow region in FIG. 9, only the FOR and MREF shown in FIGS. . Accordingly, the characteristic variable calculating unit 220 can calculate the characteristic variables RFOR, RREF, VFOR and VREF to discriminate the shielded area which can not be discriminated by using FOR and MREF.

The RFOR can be calculated as a ratio of the FOR number per azimuth to the FOR average value in the class having the highest frequency in the FOR values of the radar bins having the same azimuth number (j) in the radar center as shown in Equation (3).

Here, j, i, and k denote numbers of radar bin, azimuth angle, and elevation angle, respectively. MFOR is a normalized frequency (NFD) for each empty number (j) using a FOR with the same radar bin number Distribution), it means the average value of the FOR class periods with the highest frequency in each NFD. On the other hand, as with FOR, a lower value of RFOR may mean that the corresponding radar bin is a potential shielding zone. If the RFOR of any radar bin has a relatively higher value than the RFOR of the surrounding radar bean, It can mean that it is a marine echo area. FIG. 4 is a graph showing distribution of RFORs at altitude angles of 0.0 ° and 0.4 °. Referring to FIG. 4, a very low RFOR value occurs at azimuth angles of 0 °, 37 ° and 76 °, Can be analyzed. Also, it can be seen that the RFOR value in the region adjacent to the center of the radar is small, which can be analyzed as two types of shielding or RFOR reduction due to the influence of the fluctuation of the rainfall. Therefore, in order to determine whether the low RFOR value appearing at the radar center is caused by the shielding, it should be analyzed together with other characteristic parameters to determine whether or not the shielding is performed.

RREF can be calculated as a ratio of the MREF per azimuth to the average MREF in the class having the maximum frequency at the MREF values of the radar bins of all azimuth angles having the same distance from the radar as shown in Equation (4).

Here, j, i, and k denote the radar bin, azimuth angle, and altitude angle number, respectively, and MMREF is the NFD for each bin number (j) using the MREF with the same radar bin number Means the mean value of the MREF class intervals with the highest frequency in each NFD. On the other hand, since the RFOR and the RREF in the shielding region appear to be much lower than those of the RFOR and RREF in the adjacent region, it is possible to discriminate the shielding region which can not be discriminated through FOR and MREF. Also, RREF, like MREF, indicates that if the RREF of an arbitrary radar bin is relatively low compared to the RREF of another neighboring radar bin, then the corresponding radar bin is a shielded area, and the RREF of an arbitrary radar bean is smaller than the RREF of an adjacent radar bean. If it is relatively high, it may mean that the radar bin is a terrain echo area. FIG. 5 is a graph showing the distribution of RREFs at altitude angles of 0.0 ° and 0.4 °. Referring to FIG. 5, a very low RREF value appears at an azimuth angle of 0 ° and 37 ° and 76 °. ° and 76 ° can be analyzed as a shielded area.

VFOR can be calculated from the vertical hardness of FOR at two different elevation angles, using Equation (5).

Here, Elev represents altitude angle. On the other hand, in the unshielded region, the VFOR value is less than 0 because FOR at the altitude angle below is greater than FOR at the upper altitude angle, and FOR at the upper altitude angle is less than FOR at the altitude angle Because the VFOR value is greater than 0, it can be used to determine the shielded area that can not be identified through FOR and MREF. FIG. 6 shows the distribution of VFORs at altitude angles of 0.0 ° and 0.4 °. Referring to FIG. 6, it can be seen that positive VFORs are widely distributed from the north direction to the azimuth angle of about 120 °. As a result, it can be concluded that the shield exists in the northeast part of the Gwanak mountain radar as a whole.

VREF can be calculated using Equation (6), which is the vertical gradient of the MREF at two different elevation angles.

Here, Elev represents altitude angle. On the other hand, in the unshielded region, the VREF value is smaller than 0 because the MREF at the lower elevation angle is larger than the MREF at the upper elevation angle. In the shielded region, the MREF at the upper elevation angle is larger than the MREF at the lower elevation angle, Since the value is shown as a value larger than 0, it can be used to determine the shielded area which can not be discriminated through FOR and MREF. FIG. 7 is a graph showing distribution of VREFs at altitude angles of 0.0 ° and 0.4 °. Referring to FIG. 7, it can be seen that positive VREFs are widely distributed up to an azimuth angle of 0 ° to 120 °. As a result, it can be analyzed that shielding exists in the vicinity of the azimuth angle of 0 ° to 120 °.

The terrain echo map generating unit 230 can generate the terrain echo map using the FOR and MREF calculated by the characteristic parameter calculating unit 220. [ At this time, the terrain echo map is intended to minimize the influence of the terrain echo, and may be composed of the lowest altitude angle not affected by the terrain echo.

Specifically, the terrain echo map generating unit 230 compares the FOR and MREF calculated for each radar bin by the characteristic parameter calculating unit 220 with a preset threshold value, and selects the lowest altitude angle constituting the terrain echo map . At this time, the predetermined threshold value is set in advance for each FOR and MREF, and it can be determined empirically by analyzing the PPI (Plan Posi- tion Indicator) image of FOR and MREF. The threshold value for FOR and the threshold value for MREF may be set to 30% and 25 dBZ, respectively, according to an exemplary embodiment of the present invention. The terrain echo map generating unit 230 compares the FOR and MREF of the radar bin with a preset threshold value. If at least one of the FOR and MREF is less than a predetermined threshold value, the corresponding radar bin is an area not affected by the terrain echo The altitude angle of the corresponding radar bin can be selected as the minimum altitude angle of the corresponding radar bin. On the contrary, if both FOR and MREF are equal to or greater than a preset threshold value, the terrain echo map generating unit 230 can determine that the radar bin is an area affected by the terrain echo, and is not affected by the terrain echo of the radar bin To select the minimum altitude angle, you can increase the elevation angle and compare it again with a preset threshold value. At this time, increasing the elevation angle increases the elevation angle to one level higher than the previous elevation angle. For example, if the previous elevation angle is 0.0 °, and then the elevation angle is set to 0.4 °, Lt; / RTI > The terrain echo map generating unit 230 re-calculates the FOR and MREF of the radar bin corresponding to the increased altitude angle, and re-compares the forged FOR and MREF with a preset threshold value. The terrain echo map generating unit 230 may select an elevation angle, which is increased when at least one of FOR and MREF is less than a predetermined threshold as a result of the re-comparison, as the minimum altitude angle of the corresponding radar bin. If all of the MREFs are equal to or greater than the preset threshold value, the above-described procedure can be repeated until at least one of the FOR and MREF becomes less than a preset threshold value, thereby selecting the minimum altitude angle of the corresponding radar bin. The terrain echo map generating unit 230 may generate the terrain echo map at the determined minimum altitude angle.

Hereinafter, a process of generating a beam shielding mask constituting a hybrid height-angle mask according to an embodiment of the present invention will be described with reference to FIGS. 8 is a graph showing the distribution of unshielding ratio of Gwanaksan radar at an altitude angle of 0.0 deg. Calculated by beam shielding simulation, and Fig. 9 is a graph showing distinction between shielded regions and unshielded regions at altitude angles of 0.0 and 0.4 degrees FIGS. 10A and 10B are diagrams showing normalized frequency distribution (NFD) of characteristic variables in a shielded area and an unshielded area.

The beam shield mask generation unit 240 can generate a beam shield mask that minimizes the influence of beam shielding. At this time, the beam shielding mask may be configured with a minimum altitude angle that is not affected by the beam shielding.

The beam shield mask generation unit 240 can determine a minimum altitude angle that is not affected by the beam shielding by using a normalized frequency distribution (NFD) of a characteristic parameter. At this time, in order to calculate the NFD of the characteristic variable, it is necessary to distinguish between the shielded area and the non-shielded area. The beam shield mask generation unit 240 can distinguish between the shielded area and the non-shielded area, as shown in FIG. 9, using FOR and MREF, and the non-shielding ratio calculated through the beam shielding simulation shown in FIG. At this time, the red region is a non-shielded region, the yellow region is a partially shielded region, and the blue region is a shielded region. The beam shield mask generation unit 240 according to an embodiment of the present invention is a non-shielded region when the unshielded ratio calculated by the beam shielding simulation is 90% or more, and a partially shielded region when it exceeds 65% If it is 65% or less, it can be determined as a shielded area. Also, if the beam shielding mask generation unit 240 satisfies the shielding conditions of FOR and MREF, it can be determined as a severe shielded region. At this time, the shielding condition of FOR is less than 20% for FOR and less than 25 dBZ for MREF. The beam shield mask generation unit 240 may calculate the NFD by calculating the frequency distribution of the characteristic variables for the separated shielded area and the non-shielded area, and then normalizing the frequency distribution. 10A and 10B, the beam shield mask generation unit 240 generates NFDs (indicated by solid lines in FIGS. 10A and 10B) of the characteristic variables in the shielding region and NFDs of the characteristic variables in the non- ) To detect the overlapping region between the NFD of the characteristic variable in the shielded region and the NFD of the characteristic variable in the unshielded region. At this time, the overlapped region is an area where the NFDs of the shielded region and the non-shielded region overlap, and the degree of the feature parameter can not sufficiently simulate the shielding discrimination. For example, referring to FIG. 10A, for the NFD of the FOR in the shielded area and the non-shielded area, the FOR value is superimposed in the range of 11 to 16% And the ability to identify non-shielded areas is weak. Referring to FIG. 10 (b), since the NFD of the RFOR in the shielded region and the non-shielded region is widely overlapped in the region of 0.8 to 1.2, the RFOR is better than the other characteristic variables in the shielded region and the non- It can be analyzed that it can not be discriminated. Referring to FIG. 10 (c), since the NFD of the VFOR in the shielded area and the non-shielded area is partially overlapped in the range of -5 to 0, the VFOR is smaller than the other shielded areas It can be analyzed that the non-shielded area can be discriminated well. Referring to FIG. 10 (a), since the NFD of the MREF in the shielded region and the non-shielded region has a relatively narrow overlap region in the interval of 21 to 23 dBZ, the MREF is larger than the shielded region and the non- Can be distinguished. Referring to FIG. 10B, since the NFD of the RREF in the shielded region and the non-shielded region has a narrow overlap region in the region of 0.9 to 1.1, the RREF discriminates the shielded region and the non-shielded region better than other characteristic variables Can be analyzed. Referring to FIG. 10 (c), since the NFD of the VREF in the shielded region and the non-shielded region has a very narrow overlapping region in the range of -2 to 0, VREF has a shielded region and an unshielded region It can be seen that this is a well-determined characteristic variable.

)를 산출할 수 있다.The beam shield mask generation unit 240 may calculate the weight of the characteristic variable according to the width of the detected overlapping area so as to determine the minimum altitude angle that is not affected by the beam shielding by using the NFD. The beam shield mask generation unit 240 uses the weight (?

) Can be calculated.

는 i번째 특성변수에 따른 차폐 영역과 비차폐 영역의 NFD 값의 중첩 영역의 넓이를 의미하며, S는

로 나타난다. 이때, m은 사용한 특성변수의 개수를 의미하며, 본 발명의 일 실시예에 따른 특성변수는 FOR, MREF, RFOR, RREF, VFOR, VREF로 m 값은 6이 될 수 있다. 한편, 중첩 영역의 넓이(

)는 차폐 영역과 비차폐 영역의 NFD 값이 동시에 존재하는 영역을 검출하고, 구간 별로 두 NFD 값을 서로 비교하여 최소값을 구한 뒤 누적하여 산출할 수 있다.Here, i means the type of the characteristic variable,

Denotes the width of the overlap region of the NFD values of the shielded region and the non-shielded region according to the i-th characteristic variable, and S

Respectively. In this case, m denotes the number of used characteristic variables, and the characteristic value according to an exemplary embodiment of the present invention may be 6 for FOR, MREF, RFOR, RREF, VFOR and VREF. On the other hand,

) Can detect the area where the NFD values of the shielded area and the non-shielded area coexist and calculate the minimum value by comparing the two NFD values with each other.

The beam shield mask generation unit 240 uses the NFD to determine the minimum altitude angle that is not affected by the beam shielding by using the NFD, and uses the Membership Value ) Can be calculated. The beam shield mask generation unit 240 can calculate the belonging value of the MF using Equations (8) and (9).

는 차폐 영역에 해당하는 임의의 레이더 빈 위치에서의 i번째 특성변수 p에 해당하는 차폐 영역의 NFD를 나타내고,

는 비차폐 영역에 해당하는 임의의 레이더 빈 위치에서의 i번째 특성변수 p에 해당하는 비차폐 영역의 NFD를 나타낸다. 또한,

는 차폐 영역에 해당하는 임의의 레이더 빈 위치에서 i번째 특성변수의 MF 소속값(Membership value)을 의미하며,

는 비차폐 영역에 해당하는 임의의 레이더 빈 위치에서 i번째 특성변수의 MF 소속값(Membership value)을 의미한다.Here, i denotes the type of the characteristic variable, p denotes an arbitrary value of the characteristic variable,

Represents the NFD of the shielded area corresponding to the i-th characteristic variable p at an arbitrary radar bin position corresponding to the shielded area,

Denotes the NFD of the non-shielded region corresponding to the i-th characteristic variable p at an arbitrary radar bin position corresponding to the non-shielded region. Also,

Denotes the membership value of the i-th characteristic variable at an arbitrary radar bin corresponding to the shielded area,

Denotes the membership value of the i-th characteristic variable at an arbitrary radar bin corresponding to the non-shielded area.

)와 MF의 소속값을 이용하여 빔 차폐의 영향을 받지 않는 최저 고도각을 결정할 수 있다. 구체적으로, 빔 차폐 마스크 생성부(240)는 산출한 가중치(

)와 MF의 소속값을 이용하여 종합 소속값(

)을 산출할 수 있다. 이때, 종합 소속값(

)는 수학식 10을 이용하여 산출될 수 있다.The beam shield mask generation unit 240 generates a beam shield mask

) And MF are used to determine the minimum altitude angle that is not affected by the beam shielding. More specifically, the beam shield mask generation unit 240 generates a beam shield mask

) And MF membership values,

) Can be calculated. At this time,

) Can be calculated using Equation (10).

는 i번째 특성변수의 가중치를 나타내며,

는 차폐 영역에 대한 임의의 레이더 빈 위치에서 i번째 특성변수에 대한 MF의 소속값을 나타낸다.Here, i means the type of the characteristic variable,

Represents the weight of the i-th characteristic variable,

Represents the belonging value of the MF with respect to the i-th characteristic variable at an arbitrary radar bin position with respect to the shielded area.

)을 미리 설정된 종합 소속값(

)의 문턱값과 비교하여 산출한 종합 소속값(

)이 미리 설정된 종합 소속값(

)의 문턱값 이상이면 해당 레이더 빈을 차폐 영역으로 판별하고, 미만이면 비차폐 영역으로 판별할 수 있다. 예를 들어, 산출된 종합 소속값(

)가 0.62 이상이면 해당 레이더 빈을 차폐 영역으로 판별하고, 0.62 미만이면 비차폐 영역으로 판별할 수 있다. 이때, 미리 설정된 종합 소속값(

)의 문턱값은 레이더 관측 영역의 종합 소속값(

)의 공간적 분포를 분석하여 경험적으로 결정될 수 있다. 빔 차폐 마스크 생성부(240)는 비차폐 영역으로 판별된 레이더 빈의 고도각을 해당 레이더 빈의 최저 고도각으로 선택할 수 있다. 빔 차폐 마스크 생성부(240)는 차폐 영역으로 판별된 레이더 빈의 현재 고도각은 빔 차폐에 의한 영향을 받는 고도각인 것으로 판단하고, 고도각을 증가시켜 빔 차폐에 의한 영향을 받지 않는 최저 고도각을 검출할 수 있다. 이때, 빔 차폐 마스크 생성부(240)는 차폐 영역으로 판별된 레이더 빈의 고도각을 한단계 위의 고도각으로 증가시켜 특성변수 및 재산출한 특성변수의 NFD를 재산출하고, 재산출한 NFD를 이용하여 중첩영역을 재검출하고, 재검출한 중첩영역의 넓이를 이용하여 종합 소속값(

)을 재산출할 수 있다. 빔 차폐 마스크 생성부(240)는 재산출한 종합 소속값(

)과 미리 설정된 종합 소속값(

)의 문턱값을 비교하여 재산출한 종합 소속값(

)이 미리 설정된 종합 소속값(

)의 문턱값 미만이 되는지 여부를 확인할 수 있다. 빔 차폐 마스크 생성부(240)는 재산출한 종합 소속값(

)이 미리 설정된 종합 소속값(

)의 문턱값 미만이면 한단계 위의 고도각으로 증가시킨 레이더 빈의 고도각을 해당 레이더 빈의 최저 고도각으로 선택할 수 있다. 빔 차폐 마스크 생성부(240)는 재산출한 종합 소속값(

)이 미리 설정된 종합 소속값(

)의 문턱값 이상이면 종합 소속값(

)이 미리 설정된 종합 소속값(

)의 문턱값 이하가 될 때까지 상술한 과정을 반복하여 해당 레이더 빈의 빔 차폐의 영향을 받지 않는 최저 고도각을 선택할 수 있다. 한편, 빔 차폐의 영향을 받지 않는 최저 고도각은 고도각 별로 산출한 종합 소속값(

)을 이용하여 레이더 빈 별로 선택하는데, 같은 방위각 방향에서 인접한 레이더 빈들에 저장된 고도각 값들을 비교하여 최종적으로 결정할 수 있다. 예를 들어, 방위각이 같고 레이더 빈이 n인 위치에서 고도각이 0.8°이고, n+1번째 레이더 빈이 고도각이 0.4°이면 n번째 레이더 빈의 고도각 값이 n+1번째 고도각보다 크기 때문에 n+1번째 고도각은 0.8°로 변경될 수 있다.The beam shield mask generation unit 240 outputs the calculated global membership value (

) To a preset membership value (

) And the total membership value (

) Is a preset integrated membership value (

, It is determined that the corresponding radar bin is a shielded area, and if it is less than the threshold, it is determined that the radar bin is a non-shielded area. For example, the calculated total membership value (

) Is 0.62 or more, the corresponding radar bin is discriminated as a shielded area, and if it is less than 0.62, it can be discriminated as a non-shielded area. At this time,

) Is the total membership value of the radar observation area (

) Can be empirically determined by analyzing the spatial distribution. The beam shield mask generation unit 240 can select the altitude angle of the radar bin determined as the non-shielded area by the minimum altitude angle of the corresponding radar bin. The beam shield mask generation unit 240 determines that the current altitude angle of the radar bin determined as the shielded area is the altitude angle affected by the beam shielding and increases the altitude angle so that the lowest altitude angle that is not affected by the beam shielding Can be detected. At this time, the beam shield mask generation unit 240 re-calculates the NFD of the characteristic variable and the property parameter by increasing the elevation angle of the radar bin identified as the shielded area by one level, The overlapping area is re-detected and the total membership value (

). The beam shield mask generation unit 240 generates a global membership value

) And a preset membership value (

) Are compared with each other and the total membership value

) Is a preset integrated membership value (

≪ / RTI > is less than the threshold of < RTI ID = 0.0 > The beam shield mask generation unit 240 generates a global membership value

) Is a preset integrated membership value (

), It is possible to select the elevation angle of the radar bin which is increased to the elevation angle above one level by the lowest elevation angle of the corresponding radar bin. The beam shield mask generation unit 240 generates a global membership value

) Is a preset integrated membership value (

), The total membership value (

) Is a preset integrated membership value (

The above-described procedure is repeated until the lowest altitude angle free from the beam shielding of the corresponding radar bin is selected. On the other hand, the minimum altitude angle which is not influenced by the beam shielding is a total altitude value

). In this case, altitude angular values stored in adjacent radar bins in the same azimuth direction can be compared with each other and ultimately determined. For example, if the elevation angle is 0.8 ° and the elevation angle of the n + 1th radar bin is 0.4 ° at the same azimuth angle and the radar bin is n, then the altitude angle value of the nth radar bin is larger than the (n + 1) The (n + 1) th elevation angle can be changed to 0.8 degrees.

The beam shield mask generation unit 240 may generate a beam shield mask at a selected altitude angle through a minimum altitude angle and beam shielding simulation selected for each radar bin. At this time, the altitude angle selected through the beam shielding simulation can be selected using a non-shielding rate of less than a predetermined ratio (for example, 90%) calculated for each altitude angle.

The hybrid altitude angle mask generator 250 may generate a hybrid altitude angle mask consisting of an optimal multiple altitude angle that is not affected by the terrain echo and beam shielding. The hybrid altitude angle mask generation unit 250 combines the terrain echo map generated by the terrain echo map generation unit 230 and the beam shield mask generated through the beam shield mask generation unit 240 to generate a hybrid altitude angle mask can do.

The rainfall estimating unit 260 may perform rainfall estimation using the hybrid altitude angle mask generated by the hybrid altitude angle mask generating unit 250. At this time, when the rainfall estimation is performed using the hybrid altitude angle mask, the terrain echo area and the shielded area can be removed by the hybrid altitude angle mask, so accurate rainfall estimation can be performed irrespective of the terrain echo and beam shielding.

11A, 11B, and 11C are views showing a result of rainfall estimation verification using a hybrid altitude angle mask according to an embodiment of the present invention.

11A, 11B, and 11C, using the conventional hybrid altitude angle mask and the hybrid altitude angle mask according to an embodiment of the present invention, And Fig. 11C shows the rainfall estimation performed on May 27, 2013). In this case, the radar reflectivity is -4.11 dBZ, -4.29 dBZ, and -8.13 dBZ, respectively. Referring to FIG. 11A, the rainfall intensity estimated based on the existing hybrid altitude angle mask has red dots that are discriminated as terrestrial echoes in the west coast region of Chungcheongnam-do and the vicinity of Chungcheong Island (the area denoted by a red circle in FIG. 11A) Remains. On the other hand, referring to (b) of FIG. 11, it can be seen that the rainfall intensity estimated based on the generated hybrid altitude mask according to an embodiment of the present invention does not have any red dots. 11A, 11B, and 11C, it can be seen that the terrain echo remains in the conventional hybrid altitude mask. On the other hand, referring to FIGS. 11A, 11B, and 11C (b), it can be seen that almost all of the terrain echo area is removed in the hybrid altitude mask generated according to the embodiment of the present invention. Therefore, it can be seen that the performance of the hybrid altitude mask generated according to the embodiment of the present invention is higher than that of the conventional hybrid altitude mask, and the performance of the rainfall estimation is higher than that of the existing hybrid altitude mask. The hybrid height altitude mask generated according to the example can estimate the rainfall more accurately than the existing hybrid altitude each mask.

Hereinafter, a hybrid altitude angle radar rainfall estimation method according to an embodiment of the present invention will be described with reference to FIG.

First, a weather radar reflectivity data is received from a weather radar system 100 and input 310. A statistical analysis of the received weather radar reflectivity data is performed to calculate the frequency of occlusion of reflectivity (FOR) and mean reflectivity (MREF) (315). At this time, the calculation of FOR and MREF can be calculated through Equations 1 and 2 as described above.

A topographic echo map is generated using the calculated FOR and MREF (320). A detailed terrain echo map generation method will be described later with reference to FIG.

In order to generate a beam shielding mask that is not affected by the beam shielding by using the input radar reflectivity data, additional characteristic parameters are required in addition to the calculated FOR and MREF, so that additional characteristic parameters are calculated using the calculated FOR and MREF (325). The additional characteristic variables are RFOR (Relative of FOR), RREF (Relative of mean REFlectivity), VFOR (Vertical Gradient of FOR) and VREF (Vertical Gradient of REFlectivity) can do.

The beam shielding mask which is not affected by the beam shielding is composed of the lowest altitude angle which is not affected by the beam shielding, and this minimum altitude angle can be selected by analyzing the Normalized Frequency Distribution (NFD) of the characteristic parameters. In order to calculate the NFD of the characteristic variables, the shielded area and the non-shielded area must be distinguished first. Accordingly, the shielded area and the non-shielded area are classified (330). At this time, the shielded area and the non-shielded area can be classified using the non-shielding ratio calculated through FOR, MREF and beam shielding simulation as described above.

After classifying the shielded area and the non-shielded area 330, the NFD of the characteristic parameters is calculated for each of the shielded area and the non-shielded area (335). At this time, the NFD can be calculated by calculating the frequency distribution of the characteristic variables for each of the shielded region and the non-shielded region, and then normalizing the frequency distribution.

) 및 MF(Membership Function)의 소속값을 산출한다(340). 이때, 특성변수의 가중치(

)는 상술한 것과 같이 차폐 영역의 NFD와 비차폐 영역의 NFD 값이 중첩되는 영역의 넓이를 이용하여 산출할 수 있으며, 수학식 7을 통해 산출될 수 있다. 한편, 중첩 영역의 넓이(

)는 차폐 영역과 비차폐 영역의 NFD 값이 동시에 존재하는 영역을 검출하고, 구간 별로 두 NFD 값을 서로 비교하여 최소값을 구한 뒤 누적하여 산출할 수 있다. 또한, 특성변수의 MF 소속값은 수학식 8, 9 를 통해 산출될 수 있다.In order to determine the minimum altitude angle that is not affected by the beam shielding by using the calculated NFD,

And membership function (MF) (340). At this time, the weight of the characteristic variable

Can be calculated using the area of the area where the NFD values of the shielded area overlap with the NFD values of the unshielded area as described above and can be calculated through Equation (7). On the other hand,

) Can detect the area where the NFD values of the shielded area and the non-shielded area coexist and calculate the minimum value by comparing the two NFD values with each other. In addition, the MF belonging value of the characteristic variable can be calculated through Equations (8) and (9).

The lowest altitude angle constituting the beam shielding mask can be determined for each radar bin, and the lowest altitude angle can be selected depending on whether the corresponding radar bin is the shielded area or not. Accordingly, in order to finally determine whether the radar bin is the shielded area, an overall belonging value capable of determining whether the radar bin is the shielded area is calculated (345). At this time, the total membership value can be calculated as the sum of values obtained by multiplying the weight values calculated for each radar bin by MF membership values as described above, and can be calculated through Equation (10).

A beam shielding mask is generated using the total membership value thus calculated (350). A detailed beam shield mask generation method will be described later with reference to FIG.

The generated terrain echo map is combined with the beam shielding mask to generate a hybrid altitude angle mask 355, and the amount of rainfall is estimated 360 using the generated hybrid altitude angle mask.

Hereinafter, a method of generating a terrain echo map according to an embodiment of the present invention will be described with reference to FIG.

)과 비교한다(410). 이때, 미리 설정된 문턱값(

)은 FOR와 MREF 별로 설정되어 있으며, FOR과 MREF의 PPI(Plan Posicion Indicator) 영상을 분석하여 경험적으로 결정될 수 있다.First, the FOR and MREF calculated for each radar bin are set to a preset threshold value (

(410). At this time, a preset threshold value (

) Is set for each FOR and MREF, and can be determined empirically by analyzing the PPI (Plan Posi- tion Indicator) image of FOR and MREF.

) 이상인지 여부를 확인(420)하고, 산출한 FOR 및 MREF 둘다 미리 설정된 문턱값(

) 이상이면 해당 레이더 빈의 고도각은 지형 에코의 영향을 받는 고도각인 것으로 판별하여 지형 에코의 영향을 받지 않는 최저 고도각을 검출하기 위해, 해당 레이더 빈의 고도각을 한단계 윗 고도각으로 증가시킨다(430). 이때, 고도각을 증가시키는 것은 미리 설정되어 있으며, 예를 들어, 고도각 0.0°다음으로 큰 고도각은 0.4°이고, 그 다음은 0.8°일 수 있다.Both the calculated FOR and MREF have a predetermined threshold value (

(420), and both the calculated FOR and MREF are compared with a preset threshold value (

), The elevation angle of the corresponding radar bin is determined to be the elevation angle affected by the terrain echo, and the elevation angle of the corresponding radar bin is incremented by one level to detect the lowest elevation angle not affected by the terrain echo (430). At this time, it is preset to increase the elevation angle, for example, an elevation angle greater than 0.0 ° and an elevation angle greater than 0.4 °, and then a value of 0.8 °.

As the elevation angle increases, the FOR and MREF of the radar bin can be changed accordingly. Accordingly, FOR and MREF corresponding to the increased altitude are calculated (440).

)과 비교한다. 이러한 과정은 레이더 빈의 FOR 및 MREF 중 하나 이상이 미리 설정된 문턱값(

) 미만이 될 때까지 반복한다.Using the increased elevation angle, the FOR and MREF reassigned are again set to a preset threshold value

). This process is repeated until at least one of the FOR and MREF of the radar bin has reached a predetermined threshold value

).

)를 비교(420)했을 때, 산출한 FOR와 MREF 중 하나 이상이 미리 설정된 문턱값(

) 미만이면 해당 레이더 빈의 현재 고도각이 지형 에코의 영향을 받지 않는 고도각인 것으로 판단하여 해당 레이더 빈의 고도각을 해당 레이더 빈의 최저 고도각으로 선택한다(450).Further, the calculated FOR and MREF and a predetermined threshold value (

(420), at least one of the calculated FOR and MREF is compared with a preset threshold value

), It is determined that the current altitude angle of the radar bin is not affected by the terrain echo, and the altitude angle of the corresponding radar bin is selected as the minimum altitude angle of the corresponding radar bin.

A terrain echo map is generated at the lowest altitude angle selected for each radar bin (460).

Hereinafter, a method of generating a beam shielding mask according to an embodiment of the present invention will be described with reference to FIG.

)를 미리 설정된 문턱값(

)과 비교한다(510). 이때, 미리 설정된 문턱값(

)은 레이더 관측 영역의 종합 소속값의 공간적 분포를 분석하여 경험적으로 결정될 수 있다.First, the total membership value calculated for each radar bin

) To a preset threshold value (

(510). At this time, a preset threshold value (

) Can be empirically determined by analyzing the spatial distribution of the integrated membership values of the radar observation region.

)가 미리 설정된 문턱값(

)이상인지 여부를 확인(520)하고, 산출한 종합 소속값(

)가 미리 설정된 문턱값(

) 이상이면, 해당 레이더 빈의 고도각은 빔 차폐에 의한 영향을 받는 고도각인 것으로 판별하여 빔 차폐에 의한 영향을 받지 않는 최저 고도각을 선택하기 위해, 해당 레이더 빈의 고도각을 한단계 윗 고도각으로 증가시킨다(530).The calculated total membership value (

Is set to a preset threshold value

(520), and the calculated total membership value (

Is set to a preset threshold value

), It is determined that the altitude angle of the radar bin is the altitude angle affected by the beam shielding, and in order to select the minimum altitude angle that is not affected by the beam shielding, the altitude angle of the radar bin is set to the one- (530).

At this time, it is preset to increase the elevation angle, for example, an elevation angle greater than 0.0 ° and an elevation angle greater than 0.4 °, and then a value of 0.8 °.

)도 변경될 수 있다. 이에 따라, 증가시킨 고도각에 해당하는 종합 소속값(

)를 산출한다(540).As the elevation angle increases, the total membership value of the radar bin

) Can also be changed. As a result, the integrated membership value (

(540).

)를 다시 미리 설정된 문턱값(

)과 비교한다. 이러한 과정은 레이더 빈의 종합 소속값(

)가 미리 설정된 문턱값(

) 미만이 될 때까지 반복한다.The total membership value of the property

) Again to a preset threshold value (

). This process is called the integration of radar bin values

Is set to a preset threshold value

).

)와 미리 설정된 문턱값(

)를 비교(520)했을 때, 산출한 종합 소속값(

)이 미리 설정된 문턱값(

)미만이면 해당 레이더 빈의 현재 고도각이 빔 차폐의 영향을 받지 않는 고도각인 것으로 판단하여 해당 레이더 빈의 고도각을 해당 레이더 빈의 최저 고도각으로 선택한다(550).In addition, the calculated total affiliation value (

) And a predetermined threshold value (

(520), the calculated total membership value (

) Is less than a preset threshold value

, It is determined that the current altitude angle of the corresponding radar bin is not affected by the beam shielding, and the altitude angle of the corresponding radar bin is selected as the minimum altitude angle of the corresponding radar bin (550).

A beam shielding mask is generated at a selected altitude angle (560) through a selected minimum altitude angle and beam shielding simulation for each radar bin. At this time, the altitude angle calculated through the beam shielding simulation can be selected by using the unshielding ratio of less than a predetermined ratio (for example, 90%) calculated for each altitude angle.

Such a technique of estimating radar rainfall using a hybrid altitude angle mask can be implemented in an application or implemented in the form of program instructions that can be executed through various computer components and recorded in a computer-readable recording medium. The computer-readable recording medium may include program commands, data files, data structures, and the like, alone or in combination.

The program instructions recorded on the computer-readable recording medium may be ones that are specially designed and configured for the present invention and are known and available to those skilled in the art of computer software.

Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like.

Examples of program instructions include machine language code such as those generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules for performing the processing according to the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

100: Weather radar system
200: Hybrid altitude radar rainfall estimator
210: weather radar data collection unit
220: characteristic variable calculating section
230: terrain echo map generation unit
240: beam shield mask generation unit
250: Hybrid altitude angle mask generating unit
260: Rainfall estimation unit

Claims (24)

A weather radar data collection unit for collecting weather radar reflectivity data;
A terrain echo map generating unit for generating a terrain echo map composed of the lowest altitude angles not affected by the terrain echo using the weather radar reflectivity data collected through the weather radar data collecting unit;
A beam shielding mask generating unit for generating a beam shielding mask having a minimum altitude angle that is not affected by beam shielding by using the weather radar reflectivity data collected through the weather radar data collecting unit;
Combining the terrain echo map and the beam shielding mask to generate a hybrid altitude angle mask comprising a lowest altitude angle at which the beam shielding area and the terrain echo area are absent in each radar bin; And
And a rainfall estimator for performing rainfall estimation through the hybrid altitude angle mask. The method according to claim 1,
The meteorological radar reflectance data collected through the meteorological radar data collecting unit is statistically analyzed to determine a frequency of occlusion of reflectivity (FOR), mean reflectivity (MREF), relativity of mean (REF) Further comprising a characteristic variable calculating unit for calculating a characteristic variable including a vertical gradient of FOR (VFOR) and a vertical gradient of REFlectivity (VREF). 3. The method of claim 2,
Wherein the terrain echo map generating unit comprises:
Wherein at least one of a Frequency of Occurrence of Reflectivity (FOR) and a Mean Reflectivity (MREF) is compared with a predetermined threshold value and a Frequency of Occurrence of Reflectivity (FOR) and Mean Reflectivity (MREF) And if the radar intensity is less than the threshold value, selects the altitude angle of the radar bin as the lowest altitude angle of the radar bin and generates the terrain echo map at the selected altitude angle. 3. The method of claim 2,
Wherein the terrain echo map generating unit comprises:
The frequency of Occurrence of Reflectivity (FOR) and the mean REFlectivity (MREF) calculated for each radar bin are compared with a preset threshold value to determine whether the frequency of Occurrence of Reflectivity (FOR) and Mean Reflectivity (MREF) Or more, the altitude angle of the radar bin is increased to select the lowest altitude angle, and the terrain echo map is generated at the selected altitude angle. 5. The method of claim 4,
Wherein the terrain echo map generating unit comprises:
The frequency of Occurrence of Ref (FOR) and Mean Reflectivity (MREF) are re-calculated according to the elevation angle of the radar bin, of the frequency of occlusion of reflectivity (FOR) and mean reflectivity (MREF) of the reed is compared with the preset threshold value, (Frequency of occlusion of reflectivity) and an MREF (Mean Reflectivity) are both equal to or greater than the preset threshold value, the frequency of occlusion of reflectivity (FOR) and the mean The hybrid altitude at which the minimum altitude angle is selected by increasing the altitude angle until at least one of the altitude and the reflectivity becomes less than the preset threshold value Radar Rainfall Estimation device. 3. The method of claim 2,
Wherein the beam shield mask generation unit comprises:
A total membership value for selecting a minimum altitude angle at which a beam-shielded region does not exist is calculated using the characteristic parameter, a minimum altitude angle is selected by comparing the calculated total membership value with a predetermined threshold value, And generates the beam shielding mask at an altitude angle selected through angle and beam shielding simulation. The method according to claim 6,
Wherein the beam shield mask generation unit comprises:
Wherein the normalized frequency distribution (NFD) of the characteristic variable is calculated for each of the shielded region and the non-shielded region using the characteristic variable, and the normalized frequency distribution (NFD) of the characteristic variable is used , Calculates the weight of the characteristic variable and the membership function (MF), and calculates the total membership value using the weight of the characteristic variable and the membership value of the shielded area for each characteristic parameter of the membership function (MF) Hybrid elevation radar rainfall estimator. 8. The method of claim 7,
The weight can be calculated using the normalized frequency distribution (NFD) of the characteristic variable in the shielding region and the width of the region in which the normalized frequency distribution (NFD) of the characteristic variable in the non-shielded region is superimposed. The radar rainfall estimated by the radar estimator.

Here, i means the type of the characteristic variable,

Represents the weight of the characteristic variable,

Is the width of the overlap region of the NFD (Normalize Frequency Distribution) values of the shielded region and the non-shielded region for the i-th characteristic variable, and S

And m denotes the number of the used characteristic variables. 8. The method of claim 7,
The membership value of the shielding area according to the characteristic variable of the MF (Membership Function) is a sum of the Normalized Frequency Distribution (NFD) of the shielded region and the Normalized Frequency Distribution (NFD) of the non- Is defined as a ratio of a normalized frequency distribution (NFD) of a shielded area, and is calculated by the following equation.

here,

Denotes Membership value of the shielding zone for each characteristic variable of the MF (Membership Function), p denotes an arbitrary value of the characteristic variable,

Represents a normalized frequency distribution (NFD) of an i-th characteristic variable at an arbitrary radar bin corresponding to the shielded area,

Denotes the Normalized Frequency Distribution (NFD) of the i-th characteristic variable at an arbitrary radar bin corresponding to the non-shielded region. 8. The method of claim 7,
Wherein the total membership value is defined as a sum of products of the weight and a membership value of a shielded area by a characteristic variable of the membership function (MF), and is calculated by the following equation: Radar rainfall estimator.

here,

Represents the total affiliation value,

Represents the weight of the characteristic variable,

Denotes the membership value of the membership function (MF) for the i-th characteristic variable at an arbitrary radar bin corresponding to the shielded area, and p denotes an arbitrary value of the characteristic variable. The method according to claim 6,
Wherein the beam shield mask generation unit comprises:
If the total membership value is less than the preset threshold value, the altitude angle of the radar bin is selected as the minimum altitude angle of the corresponding radar bin, The altitude angle of the radar bin is increased to a higher elevation angle by one step, the total belonging value is re-calculated according to the increased altitude angle, and the total belonging value of the property is compared with the preset threshold value, If the total belonging value of the property is less than the preset threshold value, the altitude angle increased is selected as the minimum altitude angle of the corresponding radar bin, and if the total belonging value of the property is not less than the predetermined threshold value, Hybrid altitude to select the lowest altitude angle by increasing the altitude angle until it is less than the threshold. Right estimation device. The weather radar data collection unit provided in the weather radar system collects the weather radar reflectivity data,
The terrain echo map generator generates a terrain echo map composed of the minimum altitude angles that are not affected by the terrain echo using the collected weather radar reflectivity data,
The beam shield mask generation unit generates a beam shield mask composed of the lowest altitude angle that is not affected by beam shielding by using the collected weather radar reflectivity data,
A hybrid altitude angle mask generation unit combines the topographic echo map and the beam shield mask to generate a hybrid altitude angle mask configured with an optimal multiple altitude angle,
Wherein the rainfall estimating unit performs rainfall estimation through the hybrid altitude angle mask. 13. The method of claim 12,
Wherein the optimal multi-elevation angle is a minimum altitude angle at which no beam shielding area and topographic echo area are present in each radar bin. 13. The method of claim 12,
Generating the terrain echo map may include:
The frequency of Occurrence of Reflectivity (FOR) and the Mean Reflectivity (MREF) are calculated for each radar bin by statistical analysis of the collected weather radar reflectivity data. Using the Frequency of Occurrence of Reflectivity (FOR) and Mean Reflectivity (MREF) A method for estimating a hybrid altitude angle radar rainfall to generate the terrain echo map. 15. The method of claim 14,
The generation of the terrain echo map using the Frequency of Occurrence of Reflectivity (FOR) and Mean Reflectivity (MREF)
The frequency of occlusion of reflectivity (FOR) and the mean reflectivity (MREF) calculated for each radar bin are compared with a predetermined threshold value, and at least one of the reflectivity FOR and the mean reflectivity (MREF) And selecting the altitude angle of the corresponding radar bin as the lowest altitude angle of the corresponding radar bin and generating the terrain echo map at the selected altitude angle if the radar bin altitude is less than the set threshold value. 15. The method of claim 14,
The generation of the terrain echo map using the Frequency of Occurrence of Reflectivity (FOR) and Mean Reflectivity (MREF)
The frequency of Occurrence of Reflectivity (FOR) and the mean REFlectivity (MREF) calculated for each radar bin are compared with a preset threshold value to determine whether the frequency of Occurrence of Reflectivity (FOR) and Mean Reflectivity (MREF) The method comprising: increasing the elevation angle of the radar bin to select the lowest altitude angle, and generating the terrain echo map at the selected altitude angle. 17. The method of claim 16,
And selecting the lowest altitude angle by increasing the altitude angle of the corresponding radar bin,
The frequency of occurence of reflectance (FOR) and the mean reflectivity (MREF) are re-calculated according to the elevation angle of the radar bin, (MREF) and the Mean Reflectivity (MREF) with the preset threshold value, and when the at least one of the RE and the MREF is less than the predetermined threshold, (Frequency of Occurrence of Reflectivity) and MREF (Mean Reflectivity) are both equal to or greater than the preset threshold value, the frequency of occlusion of reflectivity (FOR) and the mean The hybrid altitude angle selecting means selects the minimum altitude angle by increasing the altitude angle until at least one of the altitude and the reflectivity becomes less than the preset threshold value Radar rainfall estimation method. 13. The method of claim 12,
Generating the beam shielding mask comprises:
The collected meteorological radar reflectivity data is statistically analyzed to calculate a characteristic parameter for each radar bin, and a total membership value capable of selecting a minimum altitude angle at which no beam shielding zone is present is calculated using the characteristic parameter, Selecting a lowest altitude angle by comparing the belonging value with a predetermined threshold value and generating the beam shielding mask at a selected altitude angle through the selected altitude angle and beam shielding simulation. 19. The method of claim 18,
The characteristic variable includes a frequency of occlusion of reflectivity (FOR), a mean REFlectivity (MREF), a relative of FOR (RFOR), a relative gradient of RE (REF), a vertical gradient of FOR (VFOR) REFlectivity). 19. The method of claim 18,
The calculation of the total affiliation value may be performed,
Classifying the shielded region and the non-shielded region using the characteristic variable and the non-shielding ratio in the beam shielding simulation, calculating a normalized frequency distribution (NFD) of the characteristic variable by the shielded region and the non- And calculates the membership value of the shielded area by the characteristic variable of the MF (Membership Function) using the NFD (Normalize Frequency Distribution) of the characteristic variable and the membership value of the MF And calculating the total affiliation value using a membership value of a shielded area for each characteristic variable. 21. The method of claim 20,
The weight can be calculated using the normalized frequency distribution (NFD) of the characteristic variable in the shielding region and the width of the region in which the normalized frequency distribution (NFD) of the characteristic variable in the non-shielded region is superimposed. And estimating the radar intensity of each of the plurality of radars.

Here, i means the type of the characteristic variable,

Represents the weight of the characteristic variable,

Is the width of the overlap region of the NFD (Normalize Frequency Distribution) values of the shielded region and the non-shielded region for the i-th characteristic variable, and S

And m denotes the number of the used characteristic variables. 21. The method of claim 20,
The membership value of the shielding area according to the characteristic variable of the MF (Membership Function) is a sum of the Normalized Frequency Distribution (NFD) of the shielded region and the Normalized Frequency Distribution (NFD) of the non- Is defined as a ratio of a normalized frequency distribution (NFD) of a shielded area, and is calculated by the following equation.

here,

Denotes Membership value of the shielding zone for each characteristic variable of the MF (Membership Function), p denotes an arbitrary value of the characteristic variable,

Represents a normalized frequency distribution (NFD) of an i-th characteristic variable at an arbitrary radar bin corresponding to the shielded area,

Denotes the Normalized Frequency Distribution (NFD) of the i-th characteristic variable at an arbitrary radar bin corresponding to the non-shielded region. 21. The method of claim 20,
Wherein the total membership value is defined as a sum of products of the weights and membership functions (MF), and is calculated by the following equation.

here,

Represents the total affiliation value,

Represents the weight of the characteristic variable,

Denotes the membership value of the membership function (MF) for the i-th characteristic variable at an arbitrary radar bin corresponding to the shielded area, and p denotes an arbitrary value of the characteristic variable. 19. The method of claim 18,
And selecting the lowest altitude angle by comparing the total affiliation value with the preset threshold value,
If the total membership value is less than the preset threshold value, the altitude angle of the radar bin is selected as the minimum altitude angle of the corresponding radar bin, The altitude angle of the radar bin is increased to a higher elevation angle by one step, the total belonging value is re-calculated according to the increased altitude angle, and the total belonging value of the property is compared with the preset threshold value, If the total belonging value of the property is less than the preset threshold value, the altitude angle increased is selected as the minimum altitude angle of the corresponding radar bin, and if the total belonging value of the property is not less than the predetermined threshold value, Hybrid altitude to select the lowest altitude angle by increasing the altitude angle until it is less than the threshold. Right estimation method.

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