The Impact of Convection on Stratospheric Water and Cloud Fraction

Using our forward domain fill trajectory model we have run a series of experiments to explore the impact of convection on TTL cloud fraction and stratospheric water vapor.  We compare results using MERRA convective fields and a satellite-based estimate of convective cloud heights.  We compare our results to MLS stratospheric water vapor and CALIOP cloud fraction.  The use of the high spatial resolution satellite-based convective cloud heights produces little change in model stratospheric water, but a nearly 50% reduction in model high cloud fraction (well below the observed cloud fraction) compared to the model results when we use the MERRA convective fields. In order to increase the cloud fraction to observed levels we increase the mid-frequency gravity wave amplitudes.  These results suggest that mid-frequency gravity waves play a more significant role in the cloudiness of the TTL region than previously recognized.