To improve the wind and precipitation forecasts over South China, a modified orographic drag parameterization（OP） scheme that considers both the gravity wave drag（GWD） and the mountain blocking drag（MBD） effects...To improve the wind and precipitation forecasts over South China, a modified orographic drag parameterization（OP） scheme that considers both the gravity wave drag（GWD） and the mountain blocking drag（MBD） effects was implemented in the Global/Regional Assimilation and Prediction System Tropical Mesoscale Model（GRAPES-TMM）. Simulations were performed over one month starting from 1200 UTC19 June 2013. The initial and lateral boundary conditions were obtained from the NCEP global forecast system output. The simulation results were compared among a control（CTL） experiment without the OP scheme, a GWDO experiment with the OP scheme that considers only the GWD effect, and an MBD experiment with the modified OP scheme（including both GWD and MBD）. The simulation with the modified OP scheme successfully captured the main features of precipitation, including its distribution and intensity,and improved the wind circulation forecast in the lower troposphere. The modified OP scheme appears to improve the wind forecast by accelerating the ascending air motion and reinforcing the convergence in the rainfall area. Overall, the modified OP scheme exerts positive impacts on the forecast of large-scale atmospheric fields in South China.展开更多
基金Supported by the Science and Technology Key Project of the South China Regional Meteorological Center(GRMC2014M05)China Meteorological Administration Special Public Welfare Research Fund(GYHY201406003 and GYHY201206010)+1 种基金National Natural Science Foundation of China(41075083 and 41075040)Science and Technology Project of Guangdong Province(2011A032100006 and 2012A061400012)
文摘To improve the wind and precipitation forecasts over South China, a modified orographic drag parameterization（OP） scheme that considers both the gravity wave drag（GWD） and the mountain blocking drag（MBD） effects was implemented in the Global/Regional Assimilation and Prediction System Tropical Mesoscale Model（GRAPES-TMM）. Simulations were performed over one month starting from 1200 UTC19 June 2013. The initial and lateral boundary conditions were obtained from the NCEP global forecast system output. The simulation results were compared among a control（CTL） experiment without the OP scheme, a GWDO experiment with the OP scheme that considers only the GWD effect, and an MBD experiment with the modified OP scheme（including both GWD and MBD）. The simulation with the modified OP scheme successfully captured the main features of precipitation, including its distribution and intensity,and improved the wind circulation forecast in the lower troposphere. The modified OP scheme appears to improve the wind forecast by accelerating the ascending air motion and reinforcing the convergence in the rainfall area. Overall, the modified OP scheme exerts positive impacts on the forecast of large-scale atmospheric fields in South China.
