Relationship between Intensity of East Asian Summer Monsoon and Preceding Heat Content Anomaly over Western Pacific Warm Pool

Using the historical SST data provided by Japan Meteorological Agency and Hadley center,NCEP/NCAR reanalysis data (1951~2010),the relationship between the intensity of East Asian summer monsoon (EASM) and the preceding heat content anomalies over western Pacific warm pool and its possible reasons are studied.The results show that the intensity of EASM is positively related to the heat content anomalies over the warm pool.The 0~400 m heat content over the key area (-5.5°~5.5°N,157.5°~170.5°E) in preceding winter could be regarded as a good precursor of the intensity of EASM.In regressed field of atmospheric circulation against HCI and the intensity index of EASM,it is found that the western Pacific subtropical high (WPSH) is further north and much weaker.It shows strong rising motion located in the tropical monsoon trough region with greater westerly anomalies and strong sinking motion in the Meiyu front area with larger easterly anomalies.In the post February of the warm years,the position of westerly belt is further north,inducing much difference of thermal condition between sea and land in summer,which inclines to appear strong summer monsoon and vice versa.Above results indicate that the heat content anomalies are high (low) over the western Pacific warm pool in the preceding winter would cause the strong (weak) EASM.