Correlation between Spring Sandstorm Abnormity in Ningxia and Sea Temperature Abnormity in North Pacific
宁夏春季沙尘暴频次异常与北太平洋海温异常的关系研究

Based on spring sandstorm observation data in Ningxia,circumfluence characteristic values at 500 hPa,NCEP reanalyzed data,and grid data of sea water temperature in North Pacific,the relationship between the spring sandstorm frequency in Ningxia and sea temperature in North Pacific is analyzed and studied by applying the methods such as correlation analysis,synthetic analysis,wavelet transform and SVD analysis.It is found that there is an obvious negative correlation between the frequency of spring sandstorm in Ningxia and the sea temperature in California from the previous October to May in the same year;The abnormal cold(or warm) of sea temperature in key region well corresponded to the more(or less)of sandstorms in Ningxia during spring.The El Nino events in the North Pacific also affect the spring sandstorm in Ningxia significantly,fewer sandstorms relates with the El Nino pattern,vice versa.In years with colder sea water in California and during spring season in Ningxia,the Eurasian high air systems are stronger,the meridional circulation increases,lower Mongolian cyclones are favorable to guide the cold air to the south and lead to more sandstorms occurrence.Viewed from wind field,the zone from Heitao-Gansu-west Inner Mongolia-midwest Mongolia are dominated by northwest wind at high and by southeast at low,this unstable circumfluence is also advantageous to the development of sandstorms in northwest China.Besides,in colder sea water years,the East Asia troughs mostly locate west,vortex and meridional circulation are stronger,the westerly circumfluence indices are more like to be negative,the cold fronts are more dynamic, and most of the years have lower winter temperature.In warmer sea water years, the situations are basically reversed.