Effects of Gravity Wave Drag Induced by Cumulus Convection on the Atmospheric General Circulation

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Abstract
A parameterization scheme of gravity wave drag induced by cumulus convection (GWDC) is implemented in the Yonsei University atmospheric general circulation model (GCM) and the effects of GWDC on the zonal-mean flow and planetary waves are investigated through perpetual July simulations. The GWDC parameterization scheme used in this study includes a momentum gain in the cloud region to conserve the momentum. The gravity wave stress at the cloud top is concentrated in the intertropical convergence zone (ITCZ) with its maximum value of 0.14 N m−2 near the tropopause due to deep cumulus clouds. The wave breaking occurs mainly in the upper troposphere and lower stratosphere. The maximum westerly acceleration in the ITCZ is 0.6 m s−1 day−1, which is close to that observed. It is surprising to observe that the zonal wind difference between the simulations with and without the GWDC parameterization is largest in the Southern Hemisphere (SH) midlatitude stratosphere, where a westerly jet exists, rather th... Abstract A parameterization scheme of gravity wave drag induced by cumulus convection (GWDC) is implemented in the Yonsei University atmospheric general circulation model (GCM) and the effects of GWDC on the zonal-mean flow and planetary waves are investigated through perpetual July simulations. The GWDC parameterization scheme used in this study includes a momentum gain in the cloud region to conserve the momentum. The gravity wave stress at the cloud top is concentrated in the intertropical convergence zone (ITCZ) with its maximum value of 0.14 N m−2 near the tropopause due to deep cumulus clouds. The wave breaking occurs mainly in the upper troposphere and lower stratosphere. The maximum westerly acceleration in the ITCZ is 0.6 m s−1 day−1, which is close to that observed. It is surprising to observe that the zonal wind difference between the simulations with and without the GWDC parameterization is largest in the Southern Hemisphere (SH) midlatitude stratosphere, where a westerly jet exists, rather th...

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