The atmospheric circulation patterns influencing the frequency of spring sand-dust storms in the Tarim Basin

摘要

Using NCEP/NCAR reanalysis data and the sand-storm frequency data from 37 weather stations in the Tarim Basin for the period1961–2009,the relationship between the frequency of spring sandstorms in the Tarim Basin and the associated atmospheric circulation patterns is analyzed in this study.We found significantly negative correlations between sandstorm frequency and the 500-hPa geopotential height over the Paris Basin and midwestern Mongolia,while there were positive correlations over the Ural River region.The rising of the 500-hPa geopotential height in midwestern Mongolia and its falling over the Ural region correspond to a weakening of the large-scale wave patterns in the Eurasian region,which directly causes the frequency of the sand-dust storms in the Tarim Basin to decline.Also,the abrupt decline in the spring sandstorm frequency in the Tarim Basin observed in the last half-century is associated with profound changes in the atmospheric circulation in these key regions.At the interannual scale,the strengthened cyclonic atmospheric circulation patterns in the western part of Mongolia and the anticyclonic patterns over the East European plains at 500-hPa geopotential height,are responsible for frequent sandstorm occurrences in the Tarim Basin.