High-resolution satellite measurements are used to study the air-sea interaction over the Kuroshio Extension (KE) region during spring time. There are two oceanic fronts in the KE region off the east coast of Japan. These fronts are generally associated with strong ocean currents, which may display unstable meander, resulting in remarkable warm sea surface temperature (SST) ridges and cold SST troughs. Analyses of these satellite observations reveal a significantly positive correlation between sea surface wind speed and its underlying SST along these fronts. This positive SST-wind correlation be-comes even more significant when strong meanders occur along the fronts. This positive SST-wind correlation indicates an ocean-to-atmosphere feedback over the KE region during spring time. A high-resolution regional atmospheric model is used to investigate the atmospheric response to SST changes along the two fronts.
Using NCEP/NCAR daily reanalysis data and SCSMEX data, an investigation is carried out of the relationship between the position variation of the west Pacific subtropical high （WPSH） and the apparcnt heating in June 1998 based on the complete vertical vorticlty equation. It is tbund that the non-adiabatic heating plays an important role in the position variation of WPSH. In comparison with climatic mean status, the vertical change of non-adiabatic heating is stronger in the north side of WPSH in June 1998, but weaker in the south side of WPSH. The anomalous non-uniform heating induces anomalous cyclonic vorticity in South China, areas to lhe south of the Yangtze and its mid-lower valleys, but anomalous anticyclonic vorticity in the Indo-China Peninsula and South China Sea areas lead to the more southward position of WPSH than the mean.
The NCEP/NCAR II daily mean reanalysis data and observed precipitation data are employed to investigate the westward extension of the western Pacific subtropical high (WPSH) during the heavy rain period over the southern China in June 2005. Results show that there may exist a relationship between the east-west shift of the WPSH and the process of a southern China heavy rain. The analysis indicates that the vertical motion in the WPSH area is mainly caused by the latent heat release of monsoon rain belts on its northern and southern sides. The vertical motion could cause the accumulation of air mass in the center and west of the WPSH, which leads to its strengthening. The appearance of the northern and southern monsoon rain belts could not only enhance the WPSH by strengthening the descending draft, but also excite the development of positive vorticity and restrict the WPSH's movement in the north-south direction. Moreover, the Indian monsoon rainfall to the west of the WPSH may excite the development of anticyclonic vorticity on its eastern side, which leads to the westward extension of the WPSH.
