The Influences Of The Western Pacific Subtropical High On The Summer Precipitation Of Shandong Province

The simultaneous influences of the western Pacific subtropical high on the Shandong's precipitation on both seasonal and monthly time scales as well as the corresponding annual and interdecadal variations are analyzed from the viewpoints of the general circulation anomaly of the atmosphere. The NCAR/NGEP re-analyzed monthly upper air data and the monthly (June, July, August) precipitation observations from 40 weather stations in Shandong Province are used in the present paper.As far as the Shandong 's precipitation on both summer and monthly summer, the rainfall shows the distribution which inclines from the southeast to the west and to the north of the province respectively,and it's biggest area is between Moutain tai-lu-yi and Mountain ni.The rainfall in summer and July shows the same distribution.The first pattern of the rainfall in summer and monthly summer by Empirical orthogonal function (EOF) analysis is the integral identification which reflects the effect of the large-scale systems and orographic land in Shandong province,it also shows the same distribution that the biggest number areas is among mountains which lie in the middle of Shandong province and the smallest around the mountains in summer and july,it shows the distribution which inclines from the southeast to the northwest in June, and it shows the distribution which inclines from the east to the west in august.The secend pattern of the rainfall in summer and monthly summer by Empirical orthogonal function (EOF) analysis shows some deferences,it shows northeast-southwest out of phase in summer and august,it shows the north-south out of phase in june,and it shows the east-west out of phase in July.The Shandong's precipitation in summer and monthly summer has annual and interdecadal time scales,and it's interdecadal time scales in summer is infeluenced by the the western Pacific subtropical high beforeand after 1979.In summer, the western Pacific subtropical high impacts on Shandong's precipitation by deference ways with it's seasonal changes.In June, East Asia trough withdrawing from the east coast of our country, Aleutian lower pressure wadding, the 500hPa geopotential field finishing the translation from winter to summer fastly, and thus resulting in more rainfall, contraily less rainfall.In summer and July ,when the 500hPa height field increases (decreases) from South-China to South China Sea to Mashaoer islands, moisture channels to Shandong maintaining (missing),thurs less (more) rainfall. In august,when the key areas of 500hPa height field increases (decreases) which around the western Pacific subtropical high, thurs less (more) rainfall.Upwards inference of the 500hPa height field to Shandong precipitation can explain the definition of rainfall by EOF analysis.In June,when the 500hPa height field from South China Sea to Mashaoer Islands increases (decreases) and Aleutian Islands decreases (increases), thurs more (less) rainfall in northwest Shandong,and less (more) rainfall in southeast Shandong.In summer and July ,when cool air of subtropical front comes from the north, more rainfall in east and less rainfall in west Shandong, when cool air of subtropical front comes from the west, less rainfall in east and more rainfall in west Shandong.In august,when cool air of subtropical front comes from the west, more rainfall in northeast and less rainfall in southwest Shandong.In midsummer (July and August) there exist the teleconnection wave trains, which make the Shandong's summer precipitation be the pattern of east-west out of phase in July and northeast-southwest in august. The wave trains appear in the second pattern of the SVD (singular value decomposition) analysis combining the precipitation and the height field. The centers and the main axes of the wave trains are different from July and August. In July the centers are located in the western Pacific from 15-30 N, Shandong Peninsular, Korea Peninsular, and the far-east area of Russia from 50-60N, and the trend of the main axis is from north to south. While in August, the center...