THE EFFECT OF BOUNDARY LAYER PARAMETERIZATION SCHEMES ON THE SIMULATION OF TURBULENT EXCHANGE PROPERTIES OF A MEI-YU RAINSTORM
SHEN Xin-yong
MA Zheng
GUO Chun-yan
LI Xiao-fan
Abstract：Different planetary boundary layer parameterizations in the WRF model are used to simulate a heavy rainfall in Yangtze-Huaihe basin during July 3-5,2007.The results indicate that the use of different parameterization schemes has impact on the distribution and intensity of the rainstorm.The differences in precipitation rate and surface factors become larger as the rainstorm goes on.The differences in the vertical distribution of horizontal wind fields,vertical velocity and potential pseudo-equivalent temperature caused by the use of different schemes,have direct effect on the simulation of the rainstorm.The vertical distribution of turbulent kinetic energy (TKE) different from the clear state is simulated well by all schemes,with positive effect from wind shear and TKE transport and negative from buoyancy.The characteristics of turbulent exchange simulated by different schemes correspond well to those of TKE.Compared with other schemes,MYJ simulated weaker TKE development and turbulent exchange,and weaker vertical transport of heat fluxes.GBM predicted weaker exchange within the boundary layer,and much larger exchange coefficients above PBL.The vertical transport of heat flux at higher levels simulated by GBM showed obvious errors and influenced the simulation of meteorological elements in the precipitation area.Thus,further improvement is still needed.As to this case,the MYNN Level-3 scheme performs the best simulation.
Keywords：WRF modelPBL parameterization schemeMei-yu rainstormturbulent kinetic energy(TKE)turbulent exchange
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：19( 793-811 )