THE POSITION VARIATION OF THE WEST PACIFIC SUBTROPICAL HIGH AND ITS POSSIBLE MECHANISM

Using NCEP/NCAR daily reanalysis data and SCSMEX data, an investigation is carried out ofthe relationship between the position variation of the west Pacific subtropical high (WPSH) and the apparentheating in June 1998 based on the complete vertical vorticity equation. It is found that the non-adiabatic heatingplays an important role in the position variation of WPSH. In comparison with climatic mean status, the verticalchange of non-adiabatic heating is stronger in the north side of WPSH in June 1998, but weaker in the south sideof WPSH. The anomalous non-uniform heating induces anomalous cyclonic vorticity in South China, areas to thesouth of the Yangtze and its mid-lower valleys, but anomalous anticyclonic vorticity in the Indo-China Peninsulaand South China Sea areas lead to the more southward position of WPSH than the mean.