This study examines how effects of gravity wave drags induced by orgraphy (GWDO) and cumulus convection (GWDC) affect the weather and climate prediction in a global model. The global model used in this study is the Yonsei University Reserch Model System/Global Model (YOURS-GSM). The parameterization methods of GWDO and GWDC follow the Kim and Arakawa and Chun and Baik, respectively. The period of model simulations is June-July-August (JJA) for summer 1997 and December 1996, January-February 1997 (DJF) for winter season.

On the whole, the GWDO with the lower-level enhancedment of gravity wave drag reduces the zonal wind and temeprature bias by reducing the intensity of the polar night jet in the upper troposphere and lower stratosphere. It is also found that the GWDC alone does not improve the simulation results as significantly as the GWDO, but the impacts are positive when both schemes are combined through secondary circulation. The skill for medium-range forecasts is also improved.