Seasonal Variation and Heat Preference of the South Asia High

Abstract: By use of the NCEP/NCAR reanalysis data, the seasonal variation of the South Asia high (SAH) isanalyzed. The influences of temporal and spatial variations of the middle and upper level atmospheric tem-peratures, the visible heat sources, and the diabatic heating rates in the whole atmospheric column on theseasonal variation of the SAH are discussed. Results show that the SAH has two seasonal balancing modes,one of which is the land high in summer and the other the ocean high in winter. The land high itself can bedivided into two patterns as well, that is the Tibetan high and the Iranian high. Heating fields have impor-tant impacts on the seasonal variation of the SAH. The SAH is a warm high and its center has the propertyof heat preference, usually locating over or moving to an area with relatively larger heating rates. The annu-al cycle of the SAH is mainly controlled by the seasonal process of the latent and sensible heating in SouthAsia. Strong shortwave radiative heating in the north at high latitudes and over the Tibetan Plateau also hasan effects on the northward movement and maintenance of the SAH. The cooling effect of infrared radiationis an important cause in weakening the SAH.

Keywords:
• the South Asia high,
• seasonal balancing modes,
• seasonal variation,
• heating fields,
• mechanism study