Application Of Parameterization Of The Sub-Grid Orography Gravity Wave On Qinghai-Tibet Plateau And Study Of Numerical Simulation

The scheme of parameterization of Gravity Wave Drag induced by sub-grid orography(SOGWD) proposed by Kim and Arakawa(KA95) and Lott and Miller(LM97) is implemented into the Regional Assimilation and Prediction System(GRAPES),which fills up the black of physics in the GRAPES_Meso. Simulation characteristics of SOGWD in Tibetan Plateau are elaborated as follows. The blocking drag lies in 1 to 5 layer of the pattern layer and the fifth layer is far from the ground about 417 meters. The gravity wave drag lies in 5 to 10 layer of the pattern layer and the tenth layer is far from the ground about 1440 meters. The blocking drag, which corresponds to the area of large topographic standard deviation, is mainly located in the edge of the Qinghai-Tibetan Plateau. The gravity drag is induced by the flow that climbs up the mountain and the blocking is induced by the flow bypasses the mountain.So the factor determining of the ability of bypassing the mountain- Froude number and the height of the blocking layer are studied. Airflow has ability to climb up the mountain along the Himalayas and in the eastern part of Qinghai-Tibet Plateau.The Blocking layer is the highest in the seventh layer of pattern layer along the Himalayas and in the eastern part of Qinghai-Tibet Plateau. The Blocking layer is in the third layer in western Plateau and second layer in the center of the Plateau. The higher of terrain elevation the higher of blocking height from the surface. Finally the characteristics of gravity wave breaking were analyzed, and the gravity waves broken area exists stagnation point, namely wind speed u rapid decrease is close to zero,meanwhile the isentropic line will have severe changes of potential temperature significantly decreases. Through the presence of gravity wave drag parameterization scheme is used to contrast test shows that after adopting the scheme, there is a more accurate description for the lower gravity waves breaking. Lower gravity waves break occurs mainly in airflow climbs the location of the position and the downhill. Simulating the gravity wave breaking in higher layers which the CTRL test could not simulate. An example of statistical test and the batch test show that after introducing the scheme of SOGWD, height field, wind field and temperature field all are closer to the real atmosphere, and the root mean square error of wind field and temperature field become smaller.At the same time the missing negative rate is improved.