Plumes above anvils—a newly discovered stratospheric-tropospheric chemical exchange process due to deep convective clouds

Recent studies based on the NOAA AVHRR infrared imageries reveal that plumes exist above the anvil of some severe thunderstorms in extratropical regions. The nature and origin of the plumes are not understood clearly at present. This study uses a 3-D cloud dynamical and microphysical model to simulate the plume formation process and the results show that these plumes are indeed features that form above the anvil and that they are associated with the gravity wave activities and turbulent diffusion at the cloud top of severe thunderstorms. The animation of model results shows unequivocally that water vapor are transported from the troposphere to the stratosphere via the plume formation mechanism. This indicates that the same process can also transport other trace gases (ozone, NOx, SOx, etc.) and aerosol particles between the troposphere and the stratosphere since some of these species are even less prone to the freeze-dry mechanism than water vapor. This process can occur readily in the middle latitudes where the majority of the industrially related chemical species are generated and hence may have great impacts to the global atmospheric chemistry. More refined simulations are being performed. New results and animations of the simulations will be shown in the meeting.