Influence of the annual cycle of SST on the monsoon onset

• 作 者: Xingwen Jiang Jianping Li
• 机 构: InstituteofPlateauMeteorology,ChinaMeteorologicalAdministration,Chengdu,ChinaNationalKeyLaboratoryof
• 出 处: 青藏高原与邻近地区天气气候及其全球影响学术研讨会
• 发表日期: 2011年8期
• 关键词: annul cycle of the SST monsoon onset warmest SST axis Bay of Bengal

　　Differing from the traditional focus on land-sea thermal contrasts, this paper examines the influence of the annual cycle of SST on the monsoon onset.It is found that SST is a major driver of tropical circulations in the atmospheric boundary layer.In the trade wind regions, the annual cycle of SST involves a shift in the warmest SST axis (WSSTA) between two local maxima on either sides of the equator, or slight movement of WSSTA north of the equator; consequently, WSSTA has little effect on the regional meridional SST gradient and wind direction.However, in the monsoon regions, the annual cycle of SST is characterized by an abrupt northward jump of WSSTA, resulting in a marked change in regional meridional SST gradient and consequent onset of winds.The onset of the southwesterlies lags behind the abrupt northward jump of WSSTA.