On Shanxi Summer Interannual Climate Anomalies: 2. Seldom/Rich Rainfall in N orth/South and Rich/Seldom Rainfall in North/South Pattern
Using American National Centre of Environmental Prediction reanalysis data and monthly precipitation data at 64 observational stations of Shanxi Prov ince, the summer rainfall anomalies in1960-2003, that is the second rainfall patt ern of rich/seldom in the north and seldom/rich in the south, and temperature an omalies variation were analyzed with EOF, wavelet analysis and composite analysi s methods. The temperature linear trend indicated that warmer in the north and c ooler in the south was well accordance to the seldom rainfall in the north and r ich in the south from 1960 to 2003. The distinctive years of the second rainfall pattern were selected and the corresponding spatial and temporal distributions were made. The analysis was performed for the general circulation anomalies fea tures with 500hPa potential height field, zonal winds, 850hPa wind vector anomal ous fields, 700hPa water vapor field and water vapor transportation field. The r esults showed that the second rainfall pattern was closely related to weak East Asian summer monsoon and rich in the north or in the south were different appear ances of weak monsoon. When the rich/poor rainfall in the north and poor/rich ra infall in the south pattern happened, the subtropical high was stronger/weaker a nd presented belt/block pattern, and there was westerly/easterly anomalies in no rth/south, which meant that the northern front region was located more north. A nd the water vapor transport from the southwest to the northeast was stronger/we aker too. When rainfall was rich in the north and seldom in the south, there was a wave train appearing big circle route at mid and high latitudes, while at high latitude the latitudinal wave train appeared -+- anomalous circulation patte rn and along the coast of East Asian continent -+- anomalous circulation pattern too. Analysis of sea surface temperature showed that the second rainfall patter n has strong connection with Pacific SSTA at middle and high latitudes.