云南冬季强降温过程冷空气路径及大气环流差异  

Differences of cold air paths and atmospheric circulation during winter strong cooling processes in Yunnan

作　　者：姚愚[1] 晏红明[1] YAO Yu;YAN Hong-ming(Yunnan Climate Center,Kunming 650034,Yunnan,China)

机构地区：[1]云南省气候中心,云南昆明650034

出　　处：《云南大学学报（自然科学版）》2024年第1期94-105,共12页Journal of Yunnan University(Natural Sciences Edition)

基　　金：国家自然科学基金(U1902209)。

摘　　要：基于云南125个测站日平均气温数据,判定了1961—2020年云南冬季95次强降温过程的4种冷空气路径,对比分析了不同路径冷空气对云南降温的影响及大气环流差异.结果表明,东北路径冷空气对云南降温幅度影响最剧烈、影响空间范围最广;偏东路径出现频率最高,偏东路径和偏北路径在降温幅度和影响范围上较为接近;东南路径降温幅度和影响范围最弱,出现频率最低.超前强降温日2 d时,东北路径欧亚大陆500 hPa位势高度场上正高度距平异常区域强度和面积、700 hPa反气旋距平环流强度和西伯利亚高压均为最强,东南路径最弱,偏东路径和偏北路径介于前二者之间.东北路径500 hPa上东亚槽横槽转竖特征最明显,偏东路径和偏北路径东亚槽槽底南压加深,但转竖特征不及东北路径明显;东南路径东亚槽底部较宽广;东北路径副高呈块状面积最小,其它3种路径副高则呈带状,偏东路径副高面积最大.700 hPa上东北路径和偏东路径在日本附近有较强海平面气压负距平发展,朝鲜半岛气旋距平环流较强,其西侧较强的偏北气流引导冷空气进入云南;东南路径和偏北路径在朝鲜半岛气旋距平环流及其西侧的偏北气流较弱.在200 hPa纬向风距平场上,东北路径急流轴附近正负距平区强度最强,偏东路径沿急流轴距平分布为西正东负;东南路径正负距平区强度最弱,负距平区主要分布在急流轴北侧,偏北路径负距平区分布在急流轴南北两侧.Based on the daily average temperature data of 125 stations in Yunnan,the four paths of cold air entering Yunnan during 95 strong temperature-decreasing processes in winter from 1961 to 2020 are determined.The impacts of cold air along different paths on temperature-dropping in Yunnan and differences in atmospheric circulation are compared and analyzed.The result shows that the cold air along the northeast path has the severest impact on the temperature-dropping range and the widest spatial range of Yunnan.The easterly path has the highest frequency.The temperature-dropping ranges and impacting spatial scales of the easterly and northerly paths are close,while those of the southeast path are the weakest and least frequent.For the two days ahead of strong cooling day,the strongest are the intensity and area of positive height anomaly in the 500 hPa geopotential height field on the Eurasian continent,the intensity of the 700 hPa anticyclone anomalous circulation and the Siberian high of the northeast path,and the weakest are those of the southeast path,while between the previous two paths are those of the easterly path and the northerly path.The Eastern Asian trough at 500 hPa of the northeast path has the most obvious feature of transforming from horizontal mode to vertical mode.The trough bottoms at 500 hPa of easterly path and northerly path have deepened and moved southward,but the feature of transforming from horizontal mode to vertical mode is not as obvious as those of the northeast path.The trough bottom of southeast path is wider and broader.The subtropical high of the northeast path looks like blocks and has the smallest area,while the subtropical highs of the other three paths are banded,and the area of subtropical high in the easterly path is the largest.Both the northeast and easterly paths have strong negative sea level pressure anomaly areas near Japan,the cyclone anomaly circulations on the Korean Peninsula at 700 hPa are stronger,and the strong northerly airflow on the west side of the cyclone lead

关 键 词：云南 冬季 强降温过程 冷空气路径 环流差异 

分 类 号：P458.1[天文地球—大气科学及气象学]