Modeling Upper Troposphere and Lower Stratosphere Water Vapor from the Monsoons

We use our Forward Domain Filling model with Ames convective cloud tops to study the impact of the Asian (AM) and North American Monsoons (NAM) on the total water vapor budget of the stratosphere. The model does a good job of simulating the water vapor field as observe by MLS. We use tagged parcels to determine when a parcel has intercepted monsoon convective region from which we can determine the relative contributions from the separate monsoon circulations. We have also looked at the impact of increasing the convective heights on the simulation. Extratropical water vapor in the upper troposphere and lower stratosphere is dominated by the monsoon contributions – they individually contribute close to 50% of the observed water vapor below 82 hPa. We find that upper tropospheric/lower stratospheric air parcels that pass through the AM move both north and south – with some parcels reaching the southern tropics. The monsoons dominate the lower stratospheric water vapor field between 10N and 45N during the summer. In the upper troposphere, the monsoon influence is wider, extending into the Southern Hemisphere and the North Pole.