Effect of mesoscale topography over the Tibetan Plateau on summer precipitation in China: A regional model study

The effect of mesoscale topography over the Tibetan Plateau (TP) on downstream summer precipitation in China was studied using a regional atmospheric model. Two ensemble simulations with 30 km model resolution were conducted for the 1998 summer monsoon season in China. The control simulation used the uniform resolution for both model atmosphere and topography. In the sensitivity simulation, the mesoscale feature in topography over the TP was smoothed out with the use of the 120 km resolution topography over the TP. The results show that the control simulation reproduced reasonably well but the sensitivity simulation considerably underestimated the observed precipitation in the Yangtze River Valley (YRV). It is found that the mesoscale feature in topography plays an important role in generating and enhancing mesoscale disturbances over the TP. These disturbances enhance the surface sensible heat flux over the TP and propagate eastward to enhance convection and precipitation in the YRV in China.