本文利用 1980～2021年 MERRA2(Modern-Era Retrospective analysis for Research and Applications,version 2)沙尘资料,结合ERA5大气再分析数据,系统分析了中国春季沙尘的时空分布特征及相关的大气环流异常,结果表明:西北地区沙尘主导了我国春季沙尘的长期变化,二者均具有显著的 2～4年和 8年以上的周期变化,表现出明显的年际和年代际特征.利用EOF分析表明,EOF1主要体现我国春季沙尘,尤其是西北沙尘的年际变化,在正位相时表现出西北沙尘的显著增加.而EOF2则主要体现我国春季沙尘的年代际变化,在空间上表现为西北与中国其他地区沙尘变化的偶极子特征,其正位相为西北沙尘负异常和其他区域的正异常;在时间上则表现为 20世纪 90年代末由负转正的位相转变.进一步研究表明,中国春季沙尘变化与气象要素场具有显著的联系:当春季沙尘为正异常时,多为强风控制;此外,较高的地表温度和干旱少雨的背景利于土壤解冻和抑制沙尘沉降,最终造成沙尘天气的发生.此外,影响我国春季沙尘变化的下垫面海温异常表现出类拉尼娜型海温,且海温异常能够从前冬一直持续到同期春季,因此对提前预报春季沙尘变化提供一定的可能性.
Abstract
This study leverages the Modern-Era Retrospective analysis for Research and Applications,version 2(MERRA2)dust data spanning from 1980 to 2021,together with the fifth-generation ECMWF(ERA5)atmospheric reanalysis data,to systematically analyze the temporal and spatial distribution characteristics of spring dust in China and the underlying physical mechanisms driving these patterns.Results show that spring dust activities in Northwest China are the primary drivers of long-term changes observed across the country.These activities exhibit significant periodicities of 2-4 years and beyond 8 years,reflecting clear interannual and interdecadal fluctuations.An empirical orthogonal function(EOF)analysis was employed to identify the dominant patterns of spring dust variability in China.The first EOF mode(EOF1)mainly exhibited interannual variations in spring dust,especially in Northwestern China.The positive phase of EOF1 exhibited significantly increased spring dust anomalies in Northwestern China.By contrast,EOF2 captured pronounced interdecadal variations,displaying an east-west dipole pattern,negative dust anomalies in Northwest China,and positive anomalies in other areas during its positive phase.Notably,an interdecadal phase transition of EOF2 from negative to positive was observed around the late 1990s.Further analysis revealed a strong association between variations in spring dust activities and meteorological conditions.When spring dust levels exceed normal,they are typically driven by strong winds.In addition,high surface temperatures and a lack of precipitation facilitate soil thawing and suppress sand and dust deposition,ultimately leading to increased dust events.Furthermore,La Niña-like sea surface temperature anomalies in the tropical Pacific can affect atmospheric circulation patterns,subsequently influencing dust activities in China.These anomalies,persisting from the previous winter to the following spring,offer potential predictive insights for spring dust activities in China.
关键词
春季沙尘/中国西北/大气环流/厄尔尼诺—南方涛动
Key words
Spring dust activities/Northwestern China/Atmospheric circulation/El Niño-Southern Oscillation
维普
万方数据