Sensitivity Of Different Boundary Layer Parameterization Schemes On The Numerical Simulation Of A Rainstorm Over North China

WRF is the latest mesoscale numerical model developed by US National Center for Atmospheric Research and many other research institutions. Boundary layer parameterization schemes are a very important part of the WRF model, and the number of boundary layer schemes are continuously increased along with the development of the model WRF. Previous large number of studies have found that the simulations of storm rainfall time, area and intensity are different by taking diverse boundary layer parameterization schemes. For a specific boundary layer scheme, the simulation performance is both sensitive to the simulation area and the season.North China is one of the major industrial and agricultural producing area in our country, it is necessary to summary a relative suitable boundary layer parameterization scheme for north China rainstorm simulation. We select the rainstorm event in North China during 17-19th August,2010, to design eight numerical experiments and test the sensitivity of the rainstorm simulation to the choice of atmospheric boundary layer scheme using WRF model. Through the analysis of the numerical experiments, it is expected to find a suitable boundary layer scheme for rainstorm simulation in north China, and further reveal the physical mechanism of this precipitation process.The results show that the simulated results of different experiments differ greatly from each other. When the domain resolution is 12 km, seven experiments using boundary layer scheme all simulate strong precipitation in A, B, C and D, but there are large differences for precipitation intensity and location of heavy rain center; the rain belt of NOPBL experiment is contractive, and the simulated precipitation is more concentrated. When the resolution is 4km, seven experiments using boundary layer scheme show small-scale precipitation structure, however, the results of small-scale structure in NOPBL experiment are not obvious. MYJ experiment performs best under 12km resolution; when the domain resolution is 4 km, BouLac experiment expresses best. The addition of boundary layer scheme can improve the simulation performance of rainfall distribution, but increasing the magnitude of rainfall.The simulation results of the tests using disparate resolution and boundary layer schemes are obvious different. We do section analyze of the diagnostic quantity along the rainband of each scheme under 12 km and 4km resolution comparing with NOPBL scheme. The results further indicate that the water vapor flux convergence increases, the upward motion strengthens, and the absolute value of divergence and vorticity enlarge a lot when incorporating the boundary layer scheme.