Using TRMM-Derived Latent Heating to Estimate Momentum Flux from Convection-Induced Gravity Waves into the Lower Stratosphere

Due to a lack of observation, it is a big challenge to quantify the momentum flux transport from the troposphere into the lower stratosphere, especially by gravity waves generated by convection. This limits our understanding of the dynamics of general circulation in the stratosphere, and the interpretation of the Quasi Biennial Oscillation. In the past decade, some general circulation models have linked the momentum flux to the latent heating from subgrid scale convective precipitation with some success. However, there is still a large uncertainty in the sources of subgrid scale convection in these models. This study applies the linkage between the momentum flux and convective latent heating directly to the convective precipitation derived from 16 years of TRMM precipitation radar observations in the tropics and subtropics. The total and directional momentum flux at 100 hPa are derived at individual convective pixels by using the TRMM Spectrum Latent Heating product and large-scale wind profiles from ERA-Interim dataset. For the first time, we are able to estimate the global geographical distribution of momentum flux at 100 hPa from the observed convective sources. The diurnal, seasonal and interannual variations of the derived moment flux are presented and discussed. These results could provide a reference to validate the dynamic coupling between the tropical troposphere and the stratosphere in the general circulation models.