2024年2月我国中东部两次持续性低温雨雪冰冻过程的环流异常特征分析

Characteristics of circulation anomalies of two continuous low temperature rain and snow freezing weather processes in eastern China in February 2024

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中文摘要：2024年1月31日—2月6日和2月19-25日我国中东部地区先后发生两次持续性低温雨雪冰冻过程,均表现为降水范围广、持续时间长、降水量极端、降水相态复杂、气温显著偏低等特征,春运出行受到其较大影响.采用国家站气象观测资料和NCEP/NCAR再分析资料,对这两次过程的大尺度环流异常特征进行分析,试图揭示西太平洋副热带高压(以下简称副高)北抬原因及强冷空气活动的平流层前兆信号.结果表明:(1)我国大陆上空500 hPa"西低东高"环流形势有利于中东部地区出现持续性降水.2024年1月31日—2月6日(以下简称过程Ⅰ)乌拉尔山附近并无明显的阻塞系统;2月19-25日(以下简称过程Ⅱ)在贝加尔湖以北地区有阻塞高压发展维持.两次过程副高较常年同期偏北、显著偏强,与南支槽共同作用有利于暖湿气流向我国中东部地区输送,低层冷空气南下、暖湿空气沿低层冷垫爬升,为大范围雨雪天气提供重要的动力抬升和温度层结条件.(2)过程Ⅰ主要的水汽来源是孟加拉湾北部的偏西风输送,过程Ⅱ来自西北太平洋的水汽输送贡献更大,且江南地区整层水汽辐合强于过程Ⅰ.(3)副高偏北的原因可能是受到来自西非至北欧一带对流层中高层Rossby波能量在中纬度和副热带地区向下游传播的影响.(4)发生在2月第3候前后的平流层极涡下传可作为过程Ⅱ寒潮活动的前兆信号,平流层极涡下传超前于对流层,可为冬季我国冷空气过程提供预报依据.

外文摘要：Two persistent low temperature,rainfall/snowfall and freezing processes occurred in the central and eastern regions of China from January 1-4 and February 19-24,2024,which are mainly characterized by precipitation of wide range,long duration,extreme rainfall amount,and complex precipitation phase,and combined with significantly low temperature.These events brought serious impacts on the traf-fic during the Spring Festival.Using observation data from the National Meteorological Information Center,NCEP/NCAR reanalysis data,this work analyzed the characteristics of the large-scale circulation anomaly to reveal the reasons for the northward movement of Western Pa-cific subtropical high and the stratospheric precursor signal of the strong cold air.The results show that:(1)The situation of"low in the west and high in the east"at 500 hPa over the Chinese mainland was conducive to the occurrence of sustained precipitation in the central and eastern regions.During the first process(from January 31 to February 6,2024),there was no obvious blocking near the Ural Mountains.The second process(from February 19 to February 25,2024)was sustained by the development of blocking high in the north of Lake Baikal.Dur-ing both processes,the West Pacific subtropical high was stronger and further north than usual.Combined with the southern trough,it was conducive to the transport of warm and humid air to the central and eastern regions of China.The cold air at the lower level moved south and the warm and humid air climbed along the cold pad at the lower level,providing important dynamic lifting and temperature stratification con-ditions for a wide range of rain and snow.(2)The main source of water vapor for the first process was the abnormal westerly wind transport from the north of the Bay of Bengal.For the second process,the abnormal water vapor transport from the northwest Pacific contributed great-er,with a stronger water vapor transport flux intensity.(3)The northward deviation of the West Pacific subtropical high was possibly influ-enced by the Rossby wave energy in the middle and upper troposphere from West Africa to Northern Europe propagating downstream in the middle latitudes and subtropical regions.(4)The descent of the stratospheric polar vortex occurring around the 3rd pentad of February 2024 could be used as a precursor signal for the cold wave activity of the second process.The descent of the stratospheric polar vortex was ahead of the troposphere,providing a new basis for forecasting the cold air activities in China during winter.

外文关键词：

disaster of low temperature heavy snowfall and freezingWestern Pacific subtropical highblockingstratosphere polar vortexRossby wave

作者：

张博、张芳华

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作者单位：

国家气象中心,北京10081

关键词：

低温雨雪冰冻西太平洋副热带高压阻塞高压平流层极涡 Rossby波

基金：

中国气象局水文气象重点开放实验室开放研究项目国家自然科学基金国家重点研发计划

项目编号：

23SWQXM042422306122022YFC3003905

出版年：

2024

DOI：

10.12406/byzh.2024-108

暴雨灾害

中国气象局武汉暴雨研究所

暴雨灾害

CSTPCD

影响因子：1.533

ISSN：1004-9045

年,卷(期)：2024.43(4)