Tuning of a convective gravity wave source sheme based on HIRDLS observations

Convection as one dominant source of atmospheric gravity waves (GWs) has been in focus of investigation over recent years. However, its spatial and temporal forcing scales are not well known. In this work we address this open issue by a systematic verification of free parameters of the Yonsei convective GW source scheme based on observations from the High Resolution Dynamics Limb Sounder (HIRDLS). Observational constraints are taken into account by applying a comprehensive observational filter on the simulated GWs. By this approach, only long horizontal scale convective GWs are addressed. Results show that effects of long horizontal scale convective GWs can be successfully simulated by the superposition of three or four combinations of parameter sets reproducing the observed GW spectrum. These selected parameter sets are different for northern and southern summer. Although long horizontal scale waves are only part of the full spectrum of convective GWs, the momentum flux of these waves are found to be significant and relevant for the driving of the QBO. The zonal momentum balance is considered in vertical cross sections of GW momentum flux (GWMF) and GW drag (GWD). Global maps of the horizontal distribution of GWMF are considered and consistency between simulated results and HIRDLS observations is found. The latitude dependence of the zonal phase speed spectrum of GWMF and its change with altitude is discusse