近50a黔东南冬季凝冻时空分布及异常凝冻年环流特征分析

Analysis of Annual Circulation Characteristics of Temporal and Spatial Distribution and Abnormal Freezing in Winter in Southeastern Guizhou in Recent 50 Years

摘要: 本文利用1971~2020年黔东南16个国家站冬季(12月至次年2月)雨凇观测资料，NCEP/NCAR海平面气压、500 hPa高度场再分析资料和NOAA海表温度资料，借助M-K、EOF、小波分析及合成分析等方法对黔东南冬季凝冻的时空分布特征、时间演变规律以及环流特征进行了诊断分析研究。结果表明，黔东南雨凇总体分布形势呈西部、东部多、南北少的特点。雨凇存在较大的年际和年代际变化，从20世纪90年代初期开始雨凇呈下降的趋势；北半球强凝冻年500 hPa位势高度距平场上亚洲西部为正距平控制，整个欧亚地区50˚N以北为正距平、以南为负距平；弱凝冻年环流场中欧亚地区50˚N以北为负距平、以南为正距平。强凝冻年赤道中东太平洋海水表面温度异常偏冷，阿留申–阿拉斯加湾为负距平，热带印度洋和热带中东太平洋为显著的负距平，冷海温发展有利于冬季凝冻偏多；弱凝冻年海温距平分布与强凝冻年相反。

Abstract: Based on the observation data of winter (December to February of the following year) at 16 national stations in southeastern Guizhou from 1971 to 2020, the NCEP/NCAR sea level pressure & 500 hPa height field reanalysis data & NOAA sea surface temperature data, temporal evolution law and the characteristics of circulation situation in southeastern Guizhou in winter were studied, which are more in the west and east and less in the north and south, through M-K, EOF, wavelet analysis and synthetic analysis, the temporal and spatial distribution characteristics. The silver thaw has great interannual and interdecadal changes. From the early 1990s, the silver thaw showed a downward trend. In the 500 hPa geopotential height anomaly field in the Northern Hemisphere during strong freezing years, the western part of Asia is controlled by the positive anomaly, and the whole Eurasian region is controlled by the positive anomaly in the north of 50˚N and negative anomaly in the south; In the circulation field of the weak freezing year, the north of 50˚N in Eurasia is a negative anomaly and positive anomaly in the south. In severe freezing years, the surface temperature of the equatorial Middle East Pacific Ocean is abnormally cold, with a negative anomaly in Aleutian-Gulf of Alaska, and a significant negative anomaly in the tropical Indian Ocean and tropical Middle East Pacific Ocean. In years with strong freezing events, the sea surface temperature (SST) in the equatorial central-eastern Pacific Ocean is abnormally cold, there is a negative anomaly in the Aleutian-Gulf of Alaska, and significant negative anomalies in the tropical Indian Ocean and the tropical central-eastern Pacific Ocean. The development of cold SST is conducive to more freezing events in winter; the distribution of SST anomalies in years with weak freezing events is opposite to that in years with strong freezing events.