| 基于决策树算法的鄂东地区冰雹识别技术北大核心CSCD |
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| 引用本文： | 袁凯,李武阶,庞晶.基于决策树算法的鄂东地区冰雹识别技术北大核心CSCD[J].应用气象学报,2023,34(2):234-245. |
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| 作者姓名： | 袁凯 李武阶 庞晶 |
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| 作者单位： | 湖北省武汉市气象台, 武汉 430040 |
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| 基金项目： | 武汉市气象局临近预报创新团队项目(2022年度)。 |
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| 摘 要： | 冰雹是对流性天气常见的灾害之一,雷达是识别冰雹强有利的工具,为克服现有方法主观性强、特征量阈值不明确以及虚警率高的不足,探究机器学习算法用于冰雹识别的可行性,基于决策树算法利用2015年1月1日—2021年12月31日鄂东地区冰雹灾情资料、武汉多普勒天气雷达以及探空资料,将湿球温度高度引入冰雹识别因子中,并根据命中率、虚警率和临界成功指数定量评估其识别能力。结果表明:仅包含回波强度的决策树(强度决策树)和包含回波强度和湿球温度高度的决策树(强度-高度决策树)均能有效识别冰雹,强度-高度决策树较强度决策树的命中率和临界成功指数均小幅提高,且虚警率明显降低;强度决策树识别冰雹的关键因子为组合反射率因子,底层多为0.5°和1.5°仰角反射率因子,强度-高度决策树的关键因子为0.5°仰角反射率因子,底层多为风暴的整体强度属性;个例分析显示强度-高度决策树减少了湿球0℃层高度较高时的虚警次数,展现出良好的应用前景。
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| 关 键 词： | 冰雹 决策树算法 湿球温度高度 检验评估 |
| 收稿时间： | 2022-09-19 |
Hail Identification Technology in Eastern Hubei Based on Decision Tree Algorithm |
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| Affiliation: | Wuhan Meteorological Observatory of Hubei Province, Wuhan 430040 |
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| 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. |
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