Numerical Experiment of the Lateral Boundary Forcing Improvement of the Nesting Dynamical Model

The lateral boundary forcing effects in the buffer zones of a nesting modeling system by improving the calculation method of temperature forcing terms are simulated. This new method makes the regional climate model have the ability to describe the daily temperature evolution characteristics that are consistent with the change rules under different underlying surfaces. By using the regional climate model ASRegCM, a numerical experiment is conducted to test the effects of the lateral boundary emulation. Simulation results show that the anomalous intensity of the surface temperature and precipitation is improved with the improvement of temperature calculation in lateral boundary buffer zones, whereas there is no significant change in the distribution pattern of anomalous signs. It also shows that there is more evident improvement in the simulation of precipitation than that of surface temperature though the sensitive test is conducted on temperature only. The improvement in numerical simulation may be concluded into two aspects. One is the amplification effects on wave amplitudes of the surface temperature. The other is the effects of adding the zonal and longitudinal low frequency wave variability component with a 7~10day cycle into the process of lateral buffer emulation. The coeffects restrain the unstable convective precipitation process, and increase the continuous nonconvective precipitation process. And then the instability between cumulus convection and unconvective clouds in tropical and semi tropical zones are weakened during the model simulation.