A modeling analysis of rainfall and water cycle by the cloud-resolving WRF model over western North Pacific

Abstract

This study simulates regional precipitation, especially extreme precipitation events, and the regional hydrologic budgets over the western North Pacific region during the period from May to June 2008 by the high-resolution (4-km grid spacing) Weather Research and Forecast (WRF v3.2.1) model with explicit cloud microphysics. The model initial and boundary conditions are derived from NCEP/DOE R2 reanalysis data.

Adopting the retrieved rainfall from Tropical Rainfall Measuring Mission (TRMM) 3B42 as a reference for comparison, the WRF simulations reproduce the spatial distributions of time mean precipitation amount and rainy days. But the simulated frequency distributions of rainy days and rainfall amount show overestimated light precipitation, underestimated moderate to heavy precipitation, and well simulated extreme precipitation. The vapor budget analysis shows that the heavy precipitation is contributed mostly by the stronger moisture convergence. However, in less convective periods, the precipitation is more influenced by the surface evaporation. The vapor budget is sensitive to the cloud microphysics scheme that affects the location and strength of atmospheric latent heating and then the large-scale circulation.