IMPACT STUDY OF THE VERTICAL COORDINATE ON A NON-HYDROSTATIC MESO-SCALE HIGH-RESOLUTION MODEL

With the development of super computer techniques and the progress of correla tive subjects, it expedites the steps of development on the nonhydrostatic meso-scale high-resolution models in home and overseas, such as GRAPES ( Global/Regional Assimilation and Prediction System) in China Meteorological Administration, WRF (Weather Research and Prediction) in the United States, LM ( Local Model ) developed by German, Italy and Switzerland etc. and ALADIN model developed by France, which are all non-hydrostatic meso-scale high-resolution models. High-resolution in non-hydrostatic meso-scale numerical models is the requirement of simulating the complicated and elaborate possible process of atmosphere, and it is also a research tool and approach probing into many uncertain mechanism of atmosp heric process. However, some of techniques, such as vertical coordinate system impact the use of meso-scale non-hydrostatic numerical weather. Based on WRF (Weather Research and Forecast) model, the influence of vertical coordinates on the non-hydrostatic meso-scale high-resolution model is compared. It showed that the error of various coordinates in lower levels is almost the same when the geometry height (z) and the pressure (p) to set up a terrainfoll owing coordinate; but the error of the height terrainfollowing coordinate in higher levels is smaller than that of the pressure terrainfollowing coordinate. The higher is the resolution, the bigger is the error. The results of the high-resolution simulation exhibited that the trend of the difference in the two coordi nates existed. In addition, the correlative coefficient and standard error are also analyzed by comparison between the forecast fields and the corresponding analysis fields.