Verification Of WRF Simulation Capacity For SACOL Meteorological Elements On Different PBL Schemes Near The Ground Surface In Winter

The atmospheric boundary layer (ABL) is affected directly by the dynamic and thermodynamic impact factors of underlying surface with significant turbulence vertical exchange, in which the inter-action between land and atmosphere and air pollution are mainly existed. Energy activities in ABL provide energy for the development of global atmospheric system, land surface process and terrain change also provide dynamic forcing for atmospheric motion. ABL researches have profound influence on weather forecasting, climate change, and thus human life. With the increasingly serious global drying trend, the climate change over semi-arid region presents more and more importance in the research of global climate change. In the arid and semi-arid region, the biological, physical, and chemical processes between the underlying surface and atmosphere is very complex, and their properties still cannot be exactly and comprehensively gained.The surface temperature, wind speed, sensible heat, and latent heat over the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) from1to6December2009are simulated using three different planetary boundary layer (PBL) parameterization schemes (YSU, MYJ, and ACM2) in WRF model, and then compared with observation. The capacities of WRF model over complex terrain were testified by comparing simulated results with observation, the difference between the meteorological fields from three PBL schemes were discussed, and then the capability of WRF model in the simulation with high resolution over the Loess Plateau and validated.(1) Comparison between the observations and simulations shows that the metrological variables from three PBL schemes have similar spatial distributions, but the temperature in nighttime from MYJ scheme was lower than that from the other two schemes, with opposite results during the daytime, which is mainly due to the worse description of the local closed MYJ scheme compared with YSU and ACM2schemes. The horizontal gradient of surface temperature in daytime was smaller than in nighttime due to the effect of stronger turbulence mixing in daytime.(2) Local closed MYJ scheme presents more reasonable daily changes of surface temperature under stable ABL in winter than the other non-local closed schemes (YSU and ACM2).(3) Compared with the observation, all the three PBL schemes can simulate the daily evolutions of sensible heat and latent heat, while MYJ scheme simulates best and then ACM2scheme is in the second.