A Numerical Study of Typhoon "Nepartak" Impacts on a Precipitation Event during Meiyu Period

In this paper, the effects of typhoon Nepartak on a Meiyu frontal precipitation event is explored by using the piecewise potential vorticity inversion method and the mesoscale WRF model. The results show that after weakening (strengthening) the typhoon, the water vapor flux over the rainfall area increased by 7.34% (decreased by 6.67%), the kinetic energy increased by 7.78% (decreased by 5.36%), the convective available potential energy increased by 6.66% (decreased by 5.71%), and accumulated precipitation in the Yangtze-Huaihe River basin increased by 10.21% (decreased by 8.13%). During the period when typhoon Nepartak was strengthening and approaching Mainland China, the subtropical high was forced to move northward and retreat eastward, which could directly prevent the water vapor and thermal energy from transporting to the Yangtze-Huaihe River basin along the edge of the subtropical high and indirectly lead to significant precipitation reduction and even disappearance in the area. In addition, accompanied with the intensification of typhoon, the depletion of water vapor and energy of the noumenon circulation increased, leading to decreases in water vapor and energy transport form the Bay of Bengal to Yangtze-Huaihe River basin. As a result, the Meiyu frontal precipitation terminated.