湖北省对流初生时空分布特征及其与地形关系

Spatiotemporal distribution characteristics and relationship on terrain of Convection Initiation in Hubei Province

摘要

对流初生 (Convection Initiation，CI) 是强对流天气开始活动的标志，其识别对于强对流预警具有重要意义。基于 2020-2024 年湖北省高时空分辨率雷达组合反射率拼图数据和地面自动气象站降水资料，采用改进的 CI 客观识别算法，构建湖北省 CI 数据集，并分析了 CI 的时空分布特征及其与地形的关系。结果表明：(1) 2020-2024 年湖北省识别 CI 共 107 322 次，日平均 CI 次数 59 次，日数占比 73%，其中 2020 年日平均 CI 次数和日数占比最多，2022 年最少；季节分布上，夏季最活跃，春、秋季次之，冬季最少。(2) 湖北省 CI 月变化呈双峰型，主峰位于 6-7 月，对应梅雨季，次峰位于 10-11 月，与季节转换冷暖气团交汇以及台风等热带系统影响相对应。(3) CI 日变化特征呈午后至傍晚的单峰或主峰结构，夏季后半夜存在次峰；除秋季外，白天 CI 次数普遍高于夜间。(4) CI 分布受下垫面影响显著，湖北省高频区主要集中在鄂西南山地的恩施与宜昌交界处，鄂东南幕阜山、鄂东北大别山、鄂西北山地及大型湖泊水库周边为 CI 次高频区，而中部平原盆地为低频区。上述结果反映了湖北省 CI 的发生发展规律，有助于本地化 CI 预报模型的构建，以实现对强对流天气的早发现、早预警。

Abstract

Convection Initiation (CI) is an critical precursor to severe convective weather, and its accurate identification are of great significance for severe convective weather early warning. Using high spatiotemporal resolution radar composite reflectivity mosaic data and surface automatic weather station precipitation data from Hubei Province during 2020–2024, this study applied an improved high-resolution grid-based objective CI identification algorithm to construct a CI dataset. The spatiotemporal distribution characteristics of CI and their relationship with topography were subsequently analyzed. The results are as follows. (1) A total of 107,322 CI number were identified in Hubei Province from 2020 to 2024, corresponding to an average of 59 events per day and a CI-day occurrence frequency of 73%. Both the daily mean CI number and the frequency of CI days were highest in 2020 and lowest in 2022. Seasonally, CI was most active in summer, followed by autumn and spring, and least active in winter. (2) The monthly variation of CI exhibited a bimodal pattern, with the primary peak observed in June–July, corresponding to the Meiyu season, and a secondary peak noted in October–November, associated with seasonal transition, cold-warm air convergence, and the influence of tropical systems such as typhoons. (3) The diurnal variation of CI was characterized by a single or dominant peak from afternoon to evening, with a secondary peak identified in the late night during summer. Except in autumn, daytime CI occurrences were generally higher than those at night. (4) The distribution of CI was found to be uneven and significantly influenced by underlying surfaces. High-frequency areas were concentrated mainly in the mountainous regions of southwestern Hubei, particularly along the Enshi-Yichang border. Other relatively active areas included the Mufu Mountains in southeastern Hubei, the Dabie Mountains in northeastern Hubei, mountainous regions in northwestern Hubei, and areas surrounding large lakes and reservoirs. In contrast, the central plains and basins exhibited relatively lower CI frequencies. These findings provide a preliminary understanding of the occurrence and evolution characteristics of CI in Hubei Province and offer a scientific basis for the development of a localized CI forecasting model. Such models can improve the early detection and warning of severe convective weather, thereby enhancing meteorological disaster preparedness and mitigation efforts.

关键词

对流初生 / 客观识别 / 时空分布 / 地形影响

Key words

convective initiation / objective identification / spatio-temporal distribution / topography influence

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基金资助

中国气象局创新发展专项(CXFZ2025J106)

长岛国家气候观象台开放基金项目(2024cdkfz03)

湖北省气象局科技发展基金项目(2025Y22，2025Y35)