Basic Characteristics of the Pacific Subtropical High

Monthly and seasonal variation,spatial structure,and inner sea surface temperature of the Pacific Subtropical High were studied by using reanalysis potential height data and two-meter sea surface temperature data during 1958-2010 provided by NCEP /NCAR. Results show that in horizontal direction,the center and the ridge line of the Pacific Subtropical High had southern or northern moving and its ridge point had western or eastern shift,in addition,its center had monthly zonal and meridional variation,and its shape changed obviously in June and October,it was strongest in summer and weakest in winter. In vertical direction,the Subtropical High was mainly under 300 hPa level and its intensity decreased with height,and the geopotential height gradient was the biggest near the ground which reached 40 gpm. The sea surface temperature( SST) of the Subtropical High center in Northern Hemisphere had annual cycle with period of 2-7 years,and in every cycle there was an abnormal change of SST,these changes had close links with occurence and developing of El Nino.