Objective

The objective of this proposal is to improve our fundamental understanding of transport from the troposphere into the stratosphere (trop/strat exchange).  There are several specific questions which we plan to address.  1) How important is the role of forest fires in injecting aerosols into the stratosphere (i.e. what is the total stratospheric aerosol mass loading from this source) compared to that of the two currently known sources of stratospheric aerosol: sulfates from volcanic injection of SO2 (episodic), and from upward transport of DMS emitted from the ocean surface (non-episodic)?   2) Do these aerosols have an important radiative effect?  3) What are the mechanisms for the transport of material from the troposphere to the stratosphere at mid and high latitudes (i.e. what is the relative importance of convection, such as that which occurs in the case of forest fire injection, compared to isentropic transport).   These questions have relevance for climate and global circulation models (GCMs), atmospheric chemistry, numerical weather prediction models, and aerosol transport models.