西风南支与高原季风环流场下青藏高原大气边界层结构研究

Study on the Atmospheric Boundary Layer Structure of the Qinghai-Xizang Plateau under the South Branch of the Westerly Wind and the Plateau Monsoon Circulation Field

利用第二次青藏高原(下称高原)综合科考"地-气相互作用与气候效应"立体综合加强期观测试验2019年5月、7月和10月珠峰、林芝、那曲和狮泉河站点的探空资料及ERA5再分析资料。探讨在西风南支与高原季风不同风场控制下高原大气边界层结构特征及其与感热潜热通量的关系。结果表明:西风南支风场下各站点大气边界层高度较高原夏季风风场下的大气边界层高度更高。西风南支风场下珠峰、林芝、那曲和狮泉河最高对流边界层顶分别为3250,2250,2760和3500 m。高原夏季风风场下珠峰、林芝、那曲和狮泉河最高对流边界层顶分别为2000,2100,1650和2000 m。各站点的近地层比湿特征为:7月>5月>10月。林芝地区近地层比湿比其他3个站点的比湿大,林芝近地层比湿最大达到了12.88 g·kg^(-1)。5月和10月,珠峰和林芝分别在1200 m和1500 m以上风向以偏西风为主。林芝7月1200 m以上风向以偏南风为主。狮泉河5月和10月风向以偏西西南风为主,7月风向以偏西西北风为主。珠峰、林芝和狮泉河5月和10月高空的风速较7月高空风速强的多。西风南支风场下各站点以感热通量为主,高原夏季风风场下各站点以潜热通量为主。

Using the second comprehensive scientific expedition of the Qinghai-Xizang Plateau"Land-Atmosphere Interaction and Climate Effect"three-dimensional comprehensive enhanced observation experiment May,July and October 2019 sounding data at the Mount Everest,Nyingchi,Nagqu,Shiquanhe sites and ERA5 reanalysis data.The characteristics of the atmospheric boundary layer structure of the plateau and its relationship with sensible heat and latent heat flux under the control of different wind fields in the south branch of the westerly wind and the plateau monsoon are discussed.Results show that the height of the atmospheric boundary layer at each station under the westerly south branch wind field is higher than that under the summer monsoon wind field.The height of the convective boundary layers of Mount Everest,Nyingchi,Nagqu and Shiquan River in the southwest wind field are 3250,2250,2760 and 3500 m respectively.while the height of the convective boundary layers of Mount Everest,Nyingchi,Nagqu and Shiquan River under the plateau monsoon field are 2000 m,2100 m,1650 m and 2000 m.The specific humidity of the surface layer at all site is larger on July than it on other months.The specific humidity of the surface layer in Linzhi area is larger than that of the other three regions,and it reaches 12.88 g·kg^(-1) at the maximum.The wind direction on Mount Everest over 1200 m is dominated by westerly winds in May and October.The wind direction on Nyingchi above 1500 m is dominated by westerly winds in May and October,and in July,winds above 1200 m is dominated by southerly winds.The wind direction of Shiquan River in May and October is dominated by west-southwest wind,and the wind direction of Shiquan River in July is dominated by west-northwest wind.The high-altitude wind speeds of Mount Everest,Nyingchi and Shiquanhe in May and October are much stronger than those in July.The sensible heat flux at each station under the west wind south branch wind field is dominated,and the latent heat flux at each station under the plateau summer wind field is dominated.