Comparative analysis of two heavy precipitation events in Northwest China induced by northeastward Tibetan Plateau vortices

In the summer of 2012 and 2013, two northeastward-moving Tibetan Plateau vortices (referred to as TPV) moved out of the Tibetan Plateau (referred to as plateau), and then caused heavy rain in the northwest region. In 2013, The moving path of TPV was more eastward, and the heavy rain intensity was stronger, and the falling area was eastward and wider. Based on the ERA-Interim reanalysis data and the stational precipitation data, the large-scale circulation and the influence of TPVs on the heavy precipitation were compared and analyzed during the movement of the two TPVs. The wet potential vortex is used to diagnose the two rainstorms. The results show that the Hetao high pressure ridge at 500 hPa and the westerly jet at 200 hPa have a significant impact on the movement of TPVs. The configuration of divergence (convergence) in the upper (lower) layer of the lower vortex benefits to a stronger upward movement, which provides powerful dynamic conditions for the rainstorms. The convergence of the vortex in the lower level is conducive to the transport of water vapor to the rainstorm area. The diagnostic results of barotropic wet potential vortex (MPV1) indicate that the rainstorm area in 2013 has stronger unstable conditions; the diagnosis of baroclinic wet potential vortex (MPV2) indicates that warm and humid air from the western Pacific is transported to the center of rainstorm in 2013.