Abstract ATM-9415336 Wang, Wei-Chyung SUNY Albany Title: Atmospheric Trace Constituents and Global Climate Atmospheric ozone absorbs incoming solar radiation, in particular, the UV-B radiation and acts as s greenhouse gas by absorbing outgoing longwave radiation. Recent studies suggest that the observed ozone changes in the stratosphere and troposphere can substantially perturb the radiative forcing with important climate implications. However, large uncertainties exist, mainly related to radiative transfer schemes and vertical distributions of ozone and temperature. In addition, ozone is a secondary constituent formed by chemical reactions in the atmosphere involving several precursors (NOx, hydrocarbons and CO). The concentrations of these precursors depend on the oxidation process in the atmosphere, which varies strongly with time and space (and thus the climate state) and depends, in addition to the precursors, on the hydrogen radicals like OH and HO2. There fore, it is necessary to have a self-consistent chemistry-radiative-dynamical model to stimulate the observed ozone changes and account for the feedbacks in computing the radiative forcing. Concerns have also been raised in recent years about the climatic efffect due to increasing tropospheric sulfate aerosols of anthropogenic origin. The aerosols are expected to cool the surface by directly backscattering the solar radiation and directly enhancing the cloud albedo due to increased aerosol cloud condensation nuclei. However, large uncertainties exist in the calculated radiative forcing, in particular the enhancement of the cloud albedo, and its climatic effect. This project will continue modeling and observational studies of "global climate and atmospheric trace constituents" with focus on atmospheric ozone and sulfate aerosols. The PI will use an improved radiation model to address several issues related to the radiative forcing calculations associated with observed ozone changes. His ma in effort is to use the NCAR/GENESIS (General ENvironmental and Ecological Simulation of Interactive Systems) global model to study the direct climatic effects due to observed ozone changes and increased sulfate aerosols. For the indirect climatic effects, two exploratory tasks are initiated: the development of a coupled climate-chemistry model through continued collaboration with Prof. Ivar Isaksen at the University Oslo; and the study of increased cloud albedo associated with enhanced number density of sulfate aerosols and its parameterization for use in GENESIS through collaboration with Dr. Joyce Penner at the Lawrence Livermore National Laboratory. This research is important because it addresses questions of primary importance to global change research.
