A Composite Study of the Synoptic Differences between Major and Minor Dust Storm Springs over the China-Mongolia Areas

Abstract

In order to improve the understanding of the mean circulations of and the differences between major and minor dust storm springs over the China-Mongolia area, multiple-cases, multiple-element circulation composite analyses were conducted utilizing the NCEP/NCAR reanalysis gridded data. The main conclusions are: 1) Based on the differences in the dust storminducing system, dust origin, route of cold air and main dust storm-hit areas, the China-Mongolia dust storms regime can be divided into west, east and Southwest China-Mongolia sub-regimes; 2) During the major dust storm springs in Western China-Mongolia, circulations on the mid-and lowerlevels are characterized by a deeper and stronger Siberian high, dominant troughs or cyclones in and around Mongolia, and intensified westerly winds around the China-Mongolia border, with cold air moving frequently along northwestern or northern routes into China. During minor dust storm springs in Western China-Mongolia, the pattern is altered toward lesser cold air intrusions; 3) During major dust storm springs in Eastern China-Mongolia, circulations on the mid- and lower-levels are characterized by the dominant China-Mongolia ridges and troughs or cyclones in and around the Japan Sea, with cold air moving frequently along northeast routes into China; 4) The inter-annual and inter-decadal variations in dust storm occurrences in the last five decades are related closely to the changes in synoptic circulations; and 5) Warming in Mongolia and Southwest Siberia are accompanied with a weakening of the Siberian cold air mass and intensification of the Xingjiang ridges since the 1980¡¦s. These conditions are unfavorable for the initiation of major dust storms. Hence, if warming in this region continues in phase with the current global warming trend, dust storm activities will decrease in the future.

Read 1009 times