Hail Identification Technology in Eastern Hubei Based on Decision Tree Algorithm

Yuan Kai; Li Wujie; Pang Jing

doi:10.11898/1001-7313.20230209

Vol.34, NO.2, 2023

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Article Navigation > Journal of Applied Meteorological Science > 2023 > 34(2): 234-245

Yuan Kai, Li Wujie, Pang Jing. Hail identification technology in Eastern Hubei based on decision tree algorithm. J Appl Meteor Sci, 2023, 34(2): 234-245. DOI: 10.11898/1001-7313.20230209.

Citation:

Yuan Kai, Li Wujie, Pang Jing. Hail identification technology in Eastern Hubei based on decision tree algorithm. J Appl Meteor Sci, 2023, 34(2): 234-245. DOI: 10.11898/1001-7313.20230209.

Yuan Kai, Li Wujie, Pang Jing. Hail identification technology in Eastern Hubei based on decision tree algorithm. J Appl Meteor Sci, 2023, 34(2): 234-245. DOI: 10.11898/1001-7313.20230209.

Citation:

Yuan Kai, Li Wujie, Pang Jing. Hail identification technology in Eastern Hubei based on decision tree algorithm. J Appl Meteor Sci, 2023, 34(2): 234-245. DOI: 10.11898/1001-7313.20230209.

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Hail Identification Technology in Eastern Hubei Based on Decision Tree Algorithm

DOI: 10.11898/1001-7313.20230209

Wuhan Meteorological Observatory of Hubei Province, Wuhan 430040

Received Date: 2022-09-19
Rev Recd Date: 2022-12-17
Publish Date: 2023-03-31

Abstract

Abstract

Hail refers to the solid precipitation with a diameter greater than or equal to 5 mm caused by convection. Hail is also one main disastrous weather phenomenon in eastern Hubei, while Doppler weather radar is the most favorable tool for hail identification. At present, there are two hail identification methods used in the actual operation in eastern Hubei, one is artificial conceptual model, the other is the self-contained identification technology in short-time and proximity prediction system. The conceptual model needs to be judged by human, which is too subjective and threshold values of radar echo characteristic are not clear, while the false alarm rate(FAR) of existing automatic technologies in prediction system are too high. To overcome the shortcoming of the above methods, feasibilities of machine learning algorithms for hail identification are explored and a decision tree algorithm is established. Based on hail disaster data of Wuhan, Huanggang, Huangshi, Ezhou, Xianning and Xiaogan, Doppler weather radar data and convention high altitude sounding data of Wuhan from 2015 to 2021, the height of wet bulb 0℃(HWB0) and the height of wet bulb -20℃(HWB-20) are introduced into the hail identification factors, and artificial intelligence technology is applied in hail recognition. The performance is evaluated according to probability of detection(POD), FAR and critical success index(CSI). The result shows that both the decision tree algorithm with radar echo intensity (intensity decision tree) and the decision tree algorithm with radar echo intensity and wet bulb temperature height (intensity-height decision tree) can identify hail effectively. The POD results of the two decision tree algorithms are higher than 0.88, while the FAR are lower than 0.12, and the CSI are higher than 0.8, but the intensity-height decision tree performs better, with the POD and CSI increased by 5.68% and 7.5% than intensity decision tree respectively, while the FAR decrease 41.67%. The key factor of hail recognition by intensity decision tree is the combined reflectivity factor, and the bottom layer is the reflectivity factor of 0.5° and 1.5° elevation. The key factor of intensity-height decision tree is the reflectivity factor of 0.5° elevation and the judgment modules of radar echo extension height with the height of wet bulb temperature, especially with HWB0 included in the middle, and the bottom layer is the strength attributes of storm (vertically integrated liquid water and combined reflectivity). The analysis results of three cases with different occurrence time, location and hail size show that, due to the introduction of height of wet bulb temperature, the intensity-height decision tree reduces the number of empty alarm when the height of HWB0 and HWB-20 are high, especially when the HWB0 is high, thus reduces its FAR and improves its CSI, which indicate its potential wide prospect for operational application.
- hail;
- decision trees;
- height of wet bulb temperature;
- examination and evaluation

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References(40)

Figures and Tables

图 1 鄂东地区判别降雹的强度决策树

(a)R_c≤56.7 dBZ, (b)R_c>56.7 dBZ

Fig. 1 Decision tree of intensity for hail in eastern Hubei

(a)R_c≤56.7 dBZ, (b)R_c>56.7 dBZ

DownLoad: Full-Size Img PowerPoint

图 2 鄂东地区判别降雹的强度-高度决策树

(a)R_0.5≤51.8 dBZ, (b)R_0.5>51.8 dBZ

Fig. 2 Decision tree of intensity-height for hail in eastern Hubei

(a)R_0.5≤51.8 dBZ, (b)R_0.5>51.8 dBZ

DownLoad: Full-Size Img PowerPoint

Fig. 3 Combined reflectivity(the distance between adjacent rings is 50 km, hereinafter)(a) and reflectivity factor profile(b) of hail point of Wuhan radar at 1618 BT 26 Mar 2020

DownLoad: Full-Size Img PowerPoint

图 4 2020年3月26日16：18决策树的识别结果

(红色圆圈表示以降雹点为中心，半径为5 km的区域)

Fig. 4 Identification of decision tree at 1618 BT 26 Mar 2020

(red circle area denotes the hail location with a radius of 5 km)

DownLoad: Full-Size Img PowerPoint

Fig. 5 Combined reflectivity(a) and reflectivity factor profile(b) of hail point of Wuhan radar at 1612 BT 14 May 2021

DownLoad: Full-Size Img PowerPoint

图 6 2021年5月14日16：12决策树识别结果

(红色圆圈表示以降雹点为中心半径为5 km的区域)

Fig. 6 Identification of decision tree at 1612 BT 14 May 2021

(red circle area denotes the hail location with a radius of 5 km)

DownLoad: Full-Size Img PowerPoint

Fig. 7 Combined reflectivity(a) and reflectivity factor profile(b) of Hanchuan hail point of Wuhan radar at 1948 BT 28 Sep 2021

DownLoad: Full-Size Img PowerPoint

图 8 2021年9月28日19：48决策树识别结果

(红色圆圈表示以降雹点为中心半径为5 km的区域)

Fig. 8 Identification of decision tree at 1948 BT 28 Sep 2021

(red circle area denotes the hail location with a radius of 5 km)

DownLoad: Full-Size Img PowerPoint

Table 1 Selection standard and corresponding quantity of non-hail samples

组合反射率因子/dBZ	样本量
40.0~44.9	63
45.0~49.9	158
50.0~54.9	188
55.0~59.9	158
≥60.0	63

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Table 2 Scores of different decision trees

决策树算法	命中率	虚警率	临界成功指数
强度决策树	0.88	0.12	0.80
强度-高度决策树	0.93	0.07	0.86

DownLoad: Download CSV

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