INFLUENCE OF HEAT CONTENT ANOMALY IN THE TROPICAL WESTERN PACIFIC WARM POOL REGION ON ONSET OF SOUTH CHINA SEA SUMMER MONSOON

n n Based on the Scripps/NODC Joint Environmental Data Analysis Center's data of heat content in upper ocean (1955--1998) and NCEP/NCAR reanalysis data,the relationship between the heat content anomalies in the warm pool area of the western Pacific (WP) and onset of South China Sea summer monsoon (SCSM) is examined.The results show that the warm pool area (WP) is the place where heat content in the tropical upper layer changes with maximum range and which is most obviously influential to South China Sea summer monsoon.Onset of SCSM is very closely related to the heat content anomaly during the previous period (previous winter and spring) of the WP so that the heat content of March to April in the WP area is a very good predictor for onset of SCSM.When the heat content of the WP area is positive,convection center will be located in the South China Sea-western Pacific with strong convection,a positive anomaly of monsoon circulation and Walker circulation will take place and the subtropical high will be weaker and farther east. Positive anomalous monsoon circulation and Walker circulation will be favorable for westerly and southwesterly flows-SCSM breaks off earlier than normal.Otherwise,SCSM comes later than usual.Large-scale anomalous change of monsoon circulation and Walker circulation seems one of the important mechanisms to influence SCSM.