弱La Niňa事件下2022年春季沙尘天气特征及成因分析  

Characteristics and causes of sand-dust weather in 2022 spring under weak La Niña event

作　　者：徐玲玲 钱拴 於俐[2] 延昊 陈紫璇 XU Lingling;QIAN Shuan;YU Li;YAN Hao;CHEN Zixuan(National Meteorological Center,Beijing 100081,China;National Climate Center,Beijing 100081,China)

机构地区：[1]国家气象中心,北京100081 [2]国家气候中心,北京100081

出　　处：《气象科学》2024年第6期1134-1139,共6页Journal of the Meteorological Sciences

基　　金：国家自然科学基金资助项目(31700421);国家气象中心气象现代化专项(QXXDH202113)。

摘　　要：本文基于地面沙尘和气象观测数据,结合遥感植被指数和NCEP/NCAR再分析资料,从下垫面条件和大气环流背景两方面分析了弱La Niňa事件下2022年春季北方地区沙尘天气特征及其气候成因。结果表明:2022年春季我国北方地区共出现8次沙尘天气过程,沙尘天气发生整体偏弱、时间偏晚。2022年春季北方主要沙源地温高雨少,大部植被返青偏早但长势明显偏差、地表裸露度高,沙尘天气发生的物质条件丰富。但是乌拉尔山至贝加尔湖之间以及中国大陆地区上空500 hPa位势高度场春季转为正距平,高纬度冷空气南下偏弱,缺乏形成大范围沙尘天气所需的动力条件;加之主要沙源地附近4月偏西风强度减弱、5月盛行异常偏东风,不利于地表起沙及沙尘粒子向偏东方向输送,以上综合作用导致沙尘天气发生日数较常年同期明显偏少。2022年春季500 hPa位势高度场对La Niňa事件的非典型响应、表现为正异常是沙尘天气发生偏少最直接且重要的关键因子。tBased on surface sand-dust and meteorological observation data,combined with remote sensing Normalized Difference Vegetation Index(NDVI)and NCEP/NCAR reanalysisdata,the characteristics of sand-dust weather and its climatic causes in northern China during 2022 spring under the weak La Nina event were analyzed from underlying surface conditions and atmospheric circulation background.Results show that there were totally 8 sand-dust weather processes occurred in northern China in 2022 spring,which was generally weak and late.Because of the high air temperature and little rain in northern China in 2022 spring,most vegetation grew significantly poor in spite of its earlier regreen,which led to high surface exposure and thick dry soil layer,providing rich sand conditions for sand-dust weather.However,the 500 hPa height field between Ural Mountain and Baikal Lake and over the Chinese Mainland was positive anomalyin 2022 spring,which weakened the cold air from high latitude and resulted in lack of dynamic conditions to form a wide range of dust weather.In addition,the strength of the westerly wind near the main sand source decreased in April,and an abnormal easterly wind prevailed in May,also prevented the sand-dust particles transporting in the easterly direction.Consequently,the sand-dust weather occurrences in the northern region was significantly less than the multi-year averaged value.The positive anomaly of the 500 hPa height field was the most direct and important key factor for the less occurrence of sand-dust weathers in 2022 spring.

关 键 词：春季沙尘天气 天气气候成因 弱La Niňa事件 

分 类 号：P425.55[天文地球—大气科学及气象学]