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To support short-range weather forecasts, a high-resolution model (1km) is developed and technically upgraded in the South China Regional Center, including the improvement of the 3D reference scheme and the predictor-corrector method for semi-implicit semi-Lagrangian (SISL) in model dynamical core, as well as the improvement of physical parameterization. Furthermore, the multi-process parallel I/O and parallel nudging techniques are developed and have facilitated rapid updating in the assimilation prediction system and fast-output post processing process. The experimental results show that the improved 3D reference scheme and upgraded physic schemes can effectively improve the prediction accuracy and stability with a longer integration time step. The batch test shows that the precipitation forecast performance of 1-km model is significantly better than that of 3-km model. The 1-km model is in operation with a rapidly updating cycle at 12-minute intervals, which can be applied to short-range forecasts and nowcasting. [ABSTRACT FROM AUTHOR]

In the present study, the performance of the GRAPES model in wind simulation over south China was assessed. The simulations were evaluated by using surface observations and two sounding stations in south China. The results show that the GRAPES model could provide a reliable simulation of the distribution and diurnal variation of the wind. It showed a generally overestimated southerly wind speed especially over the Pearl River Delta region and the south of Jiangxi Province as well as the coastal region over south China. GRAPES also exhibited a large number of stations with the opposite surface wind directions over the east of Guangxi and the south of Jiangxi during the nocturnal-to-morning period, as well as an overall overestimation of surface wind over the coastal regions during the afternoon. Although GRAPES could simulate the general evolutional characteristics of vertical wind profile, it underestimated wind speed above 900 hPa and overestimated wind speed below 900 hPa. Though the parameterization scheme of gravity wave drag proved to be an effective method to alleviate the systematic deviation of wind simulation, GRAPES still exhibited large errors in wind simulation, especially in the lower and upper troposphere. [ABSTRACT FROM AUTHOR]

This review summarizes the general developments of the operational mesoscale model system based on the Global / Regional Assimilation and Prediction System-Tropical Monsoon Model (GRAPES-TMM) at the Guangzhou Regional Meteorological Center. GRAPES-TMM consists of the Tropical Regional Atmospheric Model System for the South China Sea (TRAMS, a typhoon model with a horizontal resolution of 9 km), the Mesoscale Atmospheric Regional Model System (MARS, 3km) and the fine-scale Rapid Update Cycling (RUC, 1km) forecasting system. The main advances of model dynamical core and physical processes are summarized, including the development of the 3D reference atmosphere scheme, the coupling scheme between dynamics and model physics, the calculation of nonlinear terms by fractional steps, the gravity wave drag scheme induced by sub-grid orography and a simplified model for land-surface scheme. The progress of model applications is reviewed and evaluated. The results show that the updated 9-3-1 forecasting system provides an overall improved performance on the weather forecasting in south China, especially for typhoon-genesis and typhoon-track forecasting as well as short-range weather forecasting. Capabilities and limitations as well as the future development of the forecasting system are also discussed. [ABSTRACT FROM AUTHOR]