Seasonal transition and its boundary layer characteristics in Anduo area of Tibetan Plateau

摘要

Using the data, especially the GPS rawinsode data, observed in Anduo area of the Tibetan Plateau during the intensive observation period of GAME/Tibet in 1998, the transition from the dry to the rainy season along with their boundary layer characteristics is analyzed comprehensively. The result shows that the formation of the rainy season in Anduo area is related closely to the general atmospheric circulation. The westerly belt moving north and the southeast damp current are basic conditions for development of the rainy season in Anduo area. In the dry season, the air is drier, air temperature higher, and the atmospheric boundary layer is strongly developed to cause its maximum height to reach about 3550 m. Moreover the sensible heat flux is dominant, and the latent heat flux is small in the interaction of land-atmosphere energy exchange, and a reverse humidity phenomenon occurs frequently. In the rainy season, the air is damper, air temperature lower, and the ABL height, with maximum of only about 2300 m, is lower. And the sensible heat flux becomes much smaller, the latent heat flux much larger in the interaction of land-atmosphere energy exchange. The reverse humidity phenomenon disappears.