贵州凝冻灾害事件特征和成因及其预报预测研究

Based on the frequency, the duration and catastrophe of freezing process which occurred in Guizhou in recent several decades, the freezing disaster events in Guizhou were defined. On this basis, taking into account the continuity of space and time, the regional freezing events in Guizhou were recognized in nearly 60 years and the freezing event case library was established (start date, duration, number of stations, the central site, event strength, etc.), then the strength of frozen disaster in Guizhou will be divided and its characteristics of climate change were analyzed. The new time series of frozen disaster in Guizhou were established by considering the strength and frequency of occurrence. The events characteristics in different periods, different regions, different intensity and its circulation were analyzed, meanwhile, the research of key area factor (atmosphere, ocean circulation, etc.) of typical frozen year was carried out to deepen our understanding of the formation reasons of persistent freezing events in Guizhou and provide ideas for the mid - extension period forecast of freezing disaster event. Finally, build the prediction model of winter freezing in Guizhou, by using the long-term model and seasonal climate model products to realize the mid - extended - short-term climate forecasting of Guizhou freezing disaster events, improve the prediction accuracy of freezing weather, and respond to the development of economic and social in local.

基于贵州各地历年凝冻过程的发生频次、持续天数及一定的致灾和时间持续性，对贵州的凝冻灾害事件进行定义。在此基础上，同时兼顾空间连续性，对贵州近60多年的区域性凝冻事件进行识别并建立凝冻事件个例库（开始日期、持续时间、影响站数、中心站点、事件强度等），继而对贵州凝冻灾害事件的强度进行划分并分析其气候变化特征。在综合考虑强度及发生频次的基础上，形成新的贵州凝冻灾害时间序列。分析不同时段、不同区域、不同强度的凝冻事件及其对应的环流特征，并对典型凝冻年份的同期、前期环流（大气、海洋等）关键区因子开展研究，以期加深对于贵州持续性凝冻事件形成原因的认识，为开展中期-延伸期的贵州凝冻灾害事件的预报预测提供思路。最后，搭建贵州冬季凝冻预测模型，借助中长期模式产品和季节气候模式产品，实现贵州凝冻灾害事件中期-延伸期-短期气候的无缝隙预报预测业务化，提高凝冻天气的预报预测准确率，更好服务于当地经济社会发展。

本项目收集了贵州省1961-2019年59年冬季贵州凝冻日数时空分布特征，重新确定了单站凝冻过程和区域性凝冻过程的定义、分级标准，得到了凝冻灾害事件个例库，统计了二者的时空特征，并完成不同等级区域性凝冻过程的个例的环流特征分析。59年间贵州省共计出现134次区域性凝冻过程，年均区域性凝冻过程2.3次。.对2000年以来2次超强凝冻过程的海温场、环流场、温度场进行了细致的对比分析，得到了超强凝冻过程的环流配置场模型。拉尼娜事件是两次过程的有利气候背景，东亚地区500hPa 西高东低的距平分布、850hPa切变线的稳定维持、700hPa西南急流、温度场上逆温区以及温度垂直剖面图的800～600hPa之间的融化层均是两次过程的有利的形势条件。.对典型凝冻年的同期、前期环流关键区开展研究，为冬季凝冻灾害的预测奠定基础。当前期赤道中东太平洋存在拉尼娜事件的发生发展，且西太平洋和东印度洋地区存在海温距平由负转正的异常变化时，贵州冬季凝冻日数易出现异常偏多，经向环流特征明显，高空纬向风分布比较均匀，中亚地区上空有风速大值中心；而当赤道中东太平洋出现拉尼娜事件的减弱消亡和西北太平洋海温正距平的维持时，贵州冬季凝冻日数易出现异常偏少，其亚洲中高纬盛行纬向环流，且纬向风在经向上具有明显的不对称性。并完成贵州省不同强度、不同类型区域性凝冻过程的对比分析，为凝冻过程的延伸期预测奠定基础。.利用不同起报日的NCEP气候预测模式产品，对4次区域性凝冻过程的温度场、位势高度场进行预测，以评估不同起报日的气候预测模式产品对此次过程的预测能力。并对2020年冬季的区域性凝冻过程开展中期-延伸期预测试验，实现贵州凝冻灾害的中期-延伸期-短期气候的无缝隙预报预测。检验结果表明基于NCEP气候预测模式开展的未来30天降温过程预测准确率达80%，基于NCEP气候预测模式开展的未来30天凝冻过程预测准确率达30%。