Effects of Initial/ Lateral Boundary Conditions on Regional Climate Simulations
Zheng Yiqun and Qian Yongfu(Department of Atmospheric Sciences, Nanjing University, Nanjing 210093)Gui Qijun(Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101)Yu Ge(Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008)
The simulation of the 1998 summer monsoon climate and the discussion of the effect of initial and lateral boundary conditions on simulation show that regional climate model (RegCM2) can well simulate the climate variations in monthly scale, but it should be further improved in simulating the climatic anomaly. From the simulations by adopting varied initial fields in different seasons, we find that, the simulation starting from spring is the most sensitive to the initial fields, and the deviation of the initial fields will cause a obvious effect on anaphase simulations. Relatively, the simulation starting from winter is not strongly dependent on initial fields, and the bias of initial fields will gradually decline in the later integration process, The regional climate simulation by using RegCM2 beginning from winter is suitable, in this kind of integration, the results of simulation are not notably affected by initial bias. In addition, we simply discuss the effect of using different lateral boundary schemes on climate simulations. The results show that, if adopting smaller buffer zone (five-grid-point-wide buffer zone), employing sponge lateral boundary brings about a better effect than employing exponential relaxation lateral boundary on temperature/ humidity/ geopotential height simulations, and a slight improvment also takes place in the precipitation simulations, but worse effect on the wind field simulations.