Analysis on Summer Drought in Shanxi Province and Its Cause

In terms of precipitation data of summer and corresponding NCEP/NCAR daily reanalysis data since 1961 in Shanxi province, period and intensity of drought and synthesis circulation features of typical wet and drought summers were analyzed to find out the main impact factor of summer drought. It is found that, summer precipitation of Shanxi province has obvious cycling characteristics, the most obvious precipitation of Guanzhong area are 2 a and 5～6 a; there are 3 a and 10 a in Shannan; because of insufficiency of vapour conditions, summer drought is formed easily when no trough and ridge is less evident over the continent of Europeand Asia; pre-cipitation of autumn during summmer drought years is more than normal markedly, sunspot relative number is related to summer drought in Shanxi province.