Comparison and Analysis of Two Different Calculation Schemes of SLEVE-
Hybrid Coordinate in GRAPES_MESO Model |
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| Authors: | LI Chao LI Xingliang and HU Jianglin |
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| Institution: | National Meteorological Center, CMA, Beijing 100081 China |
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| Abstract: | The calculation scheme of the smoothed-level and hybrid (SLEVE-hybrid for short) coordinates in numerical forecasting model is not limited to one. It is divided into the semi-analytical scheme and the finite differential scheme in
terms of the various differential methods of the coordinate deformation variables. Comparing the dynamic equation and the long-time batch simulation results of the two schemes, the present study draws the following conclusions. The first-
order finite difference accuracy of the coordinate deformation variables in the finite differential scheme is theoretically lower than that in the semi-analytical scheme. The larger the vertical gradient of the layer thickness is, the larger the
relative errors of the finite differential scheme are. The long-time batch simulation test in the GRAPES model dynamic core demonstrates that the bias of the temperature and the geopotential height in the semi-analytical scheme is smaller
under the default layering, while the simulation difference of the two schemes is greatly reduced when the layering is more uniform. |
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| Keywords: | GRAPES model SLEVE-hybrid coordinate dynamic core numerical modelling |
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