9705578 Hegg The main objective of this project is to include a parameterization of heterogeneous droplet chemistry into meteorological models, in particular MM5, and possibly EURAD. This parameterization will be in the form of a linear operator applied to a standard bulk parameterization of cloud chemistry. The modified Eulerian model will be tested against observations for a reasonably complete case study from the literature. Then a set of sensitivity studies will be conducted to address four specific issues: 1) To what extent does heterogeneous cloud chemistry impact chemical deposition? 2) Over what spatial and temporal scales is this heterogeneous chemistry important? 3) How does the phase partitioning of water in the clouds quantitatively affect the impact of heterogeneous chemistry? 4) Are there geographic locations or emissions/climate scenarios where heterogeneous chemistry is likely to have a particularly large impact? This effort will lead to an improved understanding of chemical and physical processes occurring in clouds.
