CN103267986B - Method for finding three-body scattering in meteorology - Google Patents
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Abstract
The invention discloses a method for finding three-body scattering in meteorology. The method comprises the following steps: finding an image area with reflectivity value higher than or equal to 60dBZ in a radar reflectivity graph and finding a target area according to the image area; performing image pretreatment to the target area to obtain a labeled graph of a weak back wave area; performing short three-body scattering identification to the labeled graph; and performing long three-body scattering identification to the labeled graph. By adopting the method, the automatic detection of the three-body scattering is realized, the disaster is pre-warned in time, and the economic loss and the personal casualty are reduced; and furthermore, the effectiveness of the method is verified by experiments.
Description
Technical field
The present invention relates to meteorology field, particularly a kind of method for finding Three body scattering in meteorology.
Background technology
Weather radar is monitored strong convective weather and one of the main tool of early warning.The electromagnetic wave of weather radar transponder pulse form, when electromagnetic wave runs into precipitation material (snowflake, raindrop and hail etc.), most of energy moves on, and has sub-fraction energy by the to all the winds scattering of precipitation material, and the energy of scattering is backward received by radar.Zrnic in 1987 finds the meteorologic phenomena of Three body scattering, and called after " Three body scattering " (TBSS), according to the theory of Zrnic, 1) ripple that sends of radar by strong hail class precipitation material strong scatter to ground downwards; 2) ripple scattering to ground again by ground scatter to original precipitation material; 3) last, ripple returns radar again.
If the electromagnetic wave of radar emission runs into strong hail at A point, as shown in Figure 1, after this, electromagnetic most of energy continues onwards transmission, remainder is scattering towards periphery, wherein, the sub-fraction of scattering wave returns radar, detects target A to show, some scattering another earthward, form close echo again and be reflected back hail A, the portion of energy of close echo is absorbed by A, and separately some continues to advance to radar.Easily find out, when the intensity of hail A is very large, the path coming from the scattering wave arrival ground of hail A is longer, the energy getting back to the ripple of hail A is more weak, if only fall in Fig. 1 with BC(or BD) march to radar for the close echo dump energy in the border circular areas of radius can support this ripple, at this moment, radar the close echo signal on this part approach ground can be misread as along electromagnetic wave sender to and weak echo E away from hail certain distance continued presence, F, G, and this Distance Theory is more than or equal to A to ground distance, i.e. AF=h, AG=AC=AD>AF, h=R × sin α, thus within the scope of FG, there is arrowband weak echo image.
Liao Yufang, Yu little Ding [1] adds up the Three body scattering phenomenon that 23 strong storms occurred in China's 11 strong convection events produce, find that each strong storm creates the strong hail of diameter at more than 2cm, wherein have 4 strong storms to create the hail that diameter is more than 10cm.That is, if S-band China New Generation Weather Radar produces Three body scattering phenomenon, then the possibility of strong hail is almost 100%, simultaneously mostly with ground disastrous gale.Showing in the statistics in the north, Hunan, all there is Three body scattering in more than the 2cm diameter hail of about 80%.Again because the duration of TBSS mostly is between 30-60min, and the time that the time lag of ground hail shooting occurs in Three body scattering, so Three body scattering can be used as strong hail warning index, moreover, D.S.ZRNIC [2] demonstrates Three body scattering also has relation with hail size, like this, Three body scattering plays vital effect for hail early warning in short-term.But whether the strong reflection rate factor that the U.S. and the strong hail algorithm of China's China New Generation Weather Radar are inspection 50dBz expands to more than-20 DEG C of layer place height, hit rate is only 70%, and false alert rate is 49%.The northern data in Hunan are added up, between 2002 to 2005 in totally 19 hailstorms, have 16 Three body scattering, account for 84%,
Inventor is realizing in process of the present invention, finds at least there is following shortcoming and defect in prior art:
Also automatically do not detect the method for Three body scattering both at home and abroad at present, again because Three body scattering may appear in each elevation angle, artificial observation is wasted time and energy, and can have influence on the ageing of forecast; And timely early warning can not be carried out to hail disaster, cause economic loss and casualties.
Summary of the invention
The invention provides a kind of method for finding Three body scattering in meteorology, this method can detect Three body scattering automatically, carries out early warning timely to disaster, reduces economic loss and casualties, described below:
For finding a method for Three body scattering in meteorology, said method comprising the steps of:
(1) from radar reflectivity figure, find the image-region that reflectance value is more than or equal to 60dBZ, and find target area according to described image-region;
(2) Image semantic classification is carried out to described target area, obtain the signature of weak echo region;
(3) short Three body scattering identification is carried out to described signature;
(4) long Three body scattering identification is carried out to described signature.
The described step according to described image-region searching target area is specially:
Using the center of described radar reflectivity figure as detection center, be angular bisector by described detection center to the ray of the geometric center of described image-region, do two rays opening 30 ° of angles, defining described detection center to the distance of the geometric center of described image-region is radius r, geometric center is h, h=r × sin α to the distance on ground, using r+h as the first distance, first distance adds 20 for second distance, and α is the elevation angle of described radar reflectivity figure; Centered by described detection center, respectively with second distance described in described first Distance geometry for radius draws circle, two rays and two are justified crossing sector region as described target area.
Describedly carry out Image semantic classification to described target area, the step obtaining the signature of weak echo region is specially:
1) do the boundary rectangle of described target area, Image semantic classification is carried out to described boundary rectangle;
2) with the direction, due east of described radar reflectivity figure for angular bisector, with described detection center for summit, do 45 angles, using angle region as the subregion such as the 0th, with the subregion such as the described 0th for benchmark is in the counterclockwise direction by radar reflectivity Fig. 8 decile, be labeled as the subregion such as the 1st to the 7th successively, record the subregional numberings such as place, described target area.
Described the step that described boundary rectangle carries out Image semantic classification to be specially:
Be white by 0 to the zone marker of 25dBZ in described target area, respective value is 1; Remaining is background, is labeled as black, and respective value is 0, obtains described signature.
Described the step that described signature carries out short Three body scattering identification to be specially:
1) template is arranged to the subregion such as each, obtain stencil function;
2) each described stencil function is substituted into described signature, obtain image function Q (x, y), if there is the point being greater than threshold value 29 in described image function Q (x, y), then there is Three body scattering.
Described the step that described signature carries out long Three body scattering identification to be specially:
Edge line is extracted to described signature, extract the chain code that described edge line carries out on eight directions, the subregions such as corresponding one of each direction, if the geometric center of described image-region is in subregions such as N, then principal direction is N direction, is in the other direction the relative direction of described principal direction; When the coding sum in described principal direction and described opposite direction is greater than threshold value with the ratio of gross yards, in described signature, there is Three body scattering.
The beneficial effect of technical scheme provided by the invention is: this method is by carrying out the identification of short Three body scattering and long Three body scattering to signature, obtain Three body scattering, achieve Three body scattering automatically to detect, early warning is timely carried out to disaster, decrease economic loss and casualties; And demonstrate the validity of this method by experiment.
Accompanying drawing explanation
Fig. 1 is Three body scattering formation basic theory schematic diagram;
Fig. 2 is target area schematic diagram;
Fig. 3 is 8 point area schematic such as grade provided by the invention;
Fig. 4 is the process flow diagram of a kind of method for finding Three body scattering in meteorology provided by the invention;
Fig. 5 is experiment effect figure.
Embodiment
For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail.
In order to automatically Three body scattering can be detected, early warning is timely carried out to disaster, reducing economic loss and casualties, embodiments providing a kind of method for finding Three body scattering in meteorology, see Fig. 4, described below:
101: from radar reflectivity figure, find the image-region that reflectance value is more than or equal to 60dBZ, and find target area according to image-region;
Wherein, the method finding target area is as follows: from radar reflectivity figure, find the image-region that reflectance value is more than or equal to 60dBZ, using the center of radar reflectivity figure as detection center, be angular bisector by detection center to the ray of the geometric center of image-region, do two rays opening 30 ° of angles, see Fig. 2, definition detection center is radius r to the distance of the geometric center of image-region, geometric center is h to the distance on ground, h=r × sin α, using r+h as the first distance, the first distance adds 20 for second distance, and α is the elevation angle of radar reflectivity figure; Centered by detection center, respectively with the first Distance geometry second distance for radius draws circle, two rays and two are justified crossing sector region as target area.
102: Image semantic classification is carried out to target area, obtain the signature of weak echo region;
Wherein, this step is specially:
1) do the boundary rectangle of target area, Image semantic classification is carried out to boundary rectangle;
Namely in the target area by 0 to 25dBZ(weak echo) zone marker be white, respective value is 1; Remaining is background, is labeled as black, and respective value is 0, obtains signature; Defined label figure function is line number and the columns that f (x, y), x and y are respectively pixel, and the value of f is 0 or 1.
2) with the direction, due east of radar reflectivity figure for angular bisector, to detect center for summit, do 45 angles, using angle region as the subregion such as the 0th, with the subregion such as the 0th for benchmark is in the counterclockwise direction by radar reflectivity Fig. 8 decile, be labeled as the subregion such as the 1st to the 7th successively, as shown in Figure 3, the subregional numberings such as place, record object region.
103: short Three body scattering identification is carried out to signature;
Wherein, this step is specially:
1) template is arranged to the subregion such as each, obtain stencil function;
Arrange a template to the subregion such as each, definition stencil function g (i, j), i, j are respectively line number and columns, and value is 0-6.The subregional template such as the 0th and the 1st as shown in Table 1 and Table 2, other etc. subregion rotate by this template, the subregional templates such as the 2nd, 4,6 respectively with the subregional template such as the 0th for benchmark is rotated counterclockwise 90 °, 180 °, 270 °; 3rd, the subregional templates such as 5,7 respectively with the subregional template such as the 1st for benchmark is rotated counterclockwise 90 °, 180 °, 270 °.
Table 1
| 0.5 | 0.5 | -1 | -1 | -1 | -1 | -1 |
| 1 | 1 | 1 | 0.5 | 0.5 | -1 | -1 |
| 1 | 1 | 1 | 1 | 1 | 1 | 0.5 |
| 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| 1 | 1 | 1 | 1 | 1 | 1 | 0.5 |
| 1 | 1 | 1 | 0.5 | 0.5 | -1 | -1 |
| 0.5 | 0.5 | -1 | -1 | -1 | -1 | -1 |
Table 2
| -1 | -1 | -1 | -1 | -1 | 0.5 | 1 |
| -1 | -1 | 0.5 | 0.5 | 1 | 1 | 0.5 |
| 0.5 | 0.5 | 1 | 1 | 1 | 1 | -1 |
| 1 | 1 | 1 | 1 | 1 | 0.5 | -1 |
| 1 | 1 | 1 | 1 | 1 | 0.5 | -1 |
| 1 | 1 | 1 | 1 | 0.5 | -1 | -1 |
| 1 | 1 | 1 | 1 | 0.5 | -1 | -1 |
2) each stencil function is substituted into signature,
obtain image function Q (x, y), if there is the point being greater than threshold value 29 in Q (x, y), then there is Three body scattering.
104: long Three body scattering identification is carried out to signature.
First edge line is extracted to signature, then the chain code [3] that edge line carries out on eight directions extracts, and the subregions such as corresponding one of each direction, if the geometric center of image-region is in subregions such as N, then principal direction is N direction, is in the other direction the relative direction of principal direction; When the coding sum in principal direction and opposite direction is greater than threshold value with the ratio of gross yards (the coding sums on eight directions), then illustrate that this boundary image is along principal direction growth, then exist Three body scattering in signature.
Such as: if target area is positioned at the 0th direction (principal direction), so require the coding in the 0th direction and the 4th direction (in the other direction) and be greater than threshold value with the ratio of coding sum, threshold value value is 1/3.Then illustrate that this boundary image is along principal direction growth, then exist Three body scattering in signature.
The feasibility of a kind of method for finding Three body scattering in meteorology that the embodiment of the present invention provides is verified below with concrete experiment, see Fig. 5, described below:
Guangdong, Jiangxi, the Tianjin reflectance map that totally 144 width contain Three body scattering is tested.In 144 examples, comprise " long Three body scattering " 27 width figure, account for 18.75%, " short Three body scattering " be totally 117 width figure, accounts for 81.25%.Detect Three body scattering totally 133 width figure in 144 figure, recall rate is 92.36%.Do not test containing the reflectance map of Three body scattering 200, Tianjin again, have two flase drops to be Three body scattering, false drop rate is 1%.Fig. 5 illustrates experiment effect figure, and in the middle of wherein visible, Three body scattering appears in the upper left corner of cloud element, and by Three body scattering region that square frame circle firmly detects.
List of references
[1] Liao Yufang, Yu little Ding, Wu Linlin, He Caifen, Yin Zhonghai. strong hailstorm radar Three body scattering statistics is analyzed [J] with an example. plateau meteorology, 2007,26 (4): 812-820.
[2]D,S,Zrnic,G,Zhang.Three-Body Scattering and Hail Size[J].JOURNAL OFAPPLIED METEOROLOGY AND CLIMATOLOGY,2010,49:687-700.
[3] Paul Gonzales. Digital Image Processing [M] .2. Beijing: Electronic Industry Press, 2003:522-524.
It will be appreciated by those skilled in the art that accompanying drawing is the schematic diagram of a preferred embodiment, the invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (2)
1. for finding a method for Three body scattering in meteorology, it is characterized in that, said method comprising the steps of:
(1) from radar reflectivity figure, find the image-region that reflectance value is more than or equal to 60dBZ, and find target area according to described image-region;
(2) Image semantic classification is carried out to described target area, obtain the signature of weak echo region;
(3) short Three body scattering identification is carried out to described signature;
(4) long Three body scattering identification is carried out to described signature;
Wherein, the described step according to described image-region searching target area is specially:
Using the center of described radar reflectivity figure as detection center, be angular bisector by described detection center to the ray of the geometric center of described image-region, do two rays opening 30 ° of angles, defining described detection center to the distance of the geometric center of described image-region is radius r, geometric center is h, h=r × sin α to the distance on ground, using r+h as the first distance, first distance adds 20 for second distance, and α is the elevation angle of described radar reflectivity figure; Centered by described detection center, respectively with second distance described in described first Distance geometry for radius draws circle, two rays and two are justified crossing sector region as described target area;
Wherein, describedly carry out Image semantic classification to described target area, the step obtaining the signature of weak echo region is specially:
1) do the boundary rectangle of described target area, Image semantic classification is carried out to described boundary rectangle;
2) with the direction, due east of described radar reflectivity figure for angular bisector, with described detection center for summit, do 45 angles, using angle region as the subregion such as the 0th, with the subregion such as the described 0th for benchmark is in the counterclockwise direction by radar reflectivity Fig. 8 decile, be labeled as the subregion such as the 1st to the 7th successively, record the subregional numberings such as place, described target area;
Wherein, described the step that described signature carries out short Three body scattering identification to be specially:
1) template is arranged to the subregion such as each, obtain stencil function;
2) each described stencil function is substituted into described signature, obtain image function Q (x, y), if there is the point being greater than threshold value 29 in described image function Q (x, y), then there is Three body scattering;
Wherein, described the step that described signature carries out long Three body scattering identification to be specially:
Edge line is extracted to described signature, extract the chain code that described edge line carries out on eight directions, the subregions such as corresponding one of each direction, if the geometric center of described image-region is in subregions such as N, then principal direction is N direction, is in the other direction the relative direction of described principal direction; When the coding sum in described principal direction and described opposite direction is greater than threshold value with the ratio of gross yards, in described signature, there is Three body scattering.
2. a kind of method for finding Three body scattering in meteorology according to claim 1, is characterized in that, is describedly specially the step that described boundary rectangle carries out Image semantic classification:
Be white by 0 to the zone marker of 25dBZ in described target area, respective value is 1; Remaining is background, is labeled as black, and respective value is 0, obtains described signature.
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