The role of the heat source of the Tibetan Plateau in the general circulation

In this paper, the thermal features of the atmosphere over the Tibetan Plateau in summer and their effects on the general circulation are reviewed. Some recent research results are reported. It is shown that the Plateau acts as a heat source in summer. Particularly the strong surface heating makes the air stratification very unstable and produces strong near-surface convergence and positive vorticity and upper layer divergence and negative vorticity. Intense convective activity generated thereby not only maintains such particular large-scale pattern over the Plateau, but also transport large amounts of sensible heat, moisture, chemical pollutants, as well as air with low ozone concentration from near-surface layers to upper layers. A minimum centre of total ozone concentration and a huge upper layer anticyclone with a warm and moist core are thus observed over the Plateau in summer. The strong divergent flow and anticyclonic vorticity source in the upper atmosphere have a strong influence on the general circulation over the world via meridional as well as longitudinal circulations, and energy dispersion on a spherical surface. It is shown that the surface sensible heating of the Plateau is essential for the occurrence of the abrupt seasonal change of the general circulation there, and for the persistent maintenance of the Asian monsoon. It is also reported that the elevated heating of the Tibetan Plateau together with its mechanical forcing cause the early onset of the Asian monsoon to happen over the eastern coast of the Bay of Bengal, which then generates a favorable circulation background for the monsoon onset over the South China Sea. The Indian monsoon onset follows afterwards.