Debra Weisenstein (PI)
Atmospheric and Environmental Research Inc.
dweisens@aer.com

Use of GMI Model to Study Tropospheric and Stratospheric Bromine Budgets

This proposal seeks funding for a three year research effort as part of the GMI Science Team under the NASA Modeling, Analysis and Prediction program.  The GMI model will be used as a tool to investigate the importance of short-lived bromine compounds to tropospheric and stratospheric chemistry, including trends in column ozone.  Measurements of stratospheric BrO imply nonzero concentrations of Bry at the tropopause, a result not obtained with models which include only CH3Br and the halons.  A recent study by Salawitch et al. has shown that lower stratospheric ozone loss would be significantly increased by assuming an additional 4-8 pptv of Bry at the tropopause and throughout the stratosphere, especially during times of aerosol enhancement following volcanic eruptions. Short-lived organic bromine compounds of biogenic origin are likely to account for the excess Bry.  We propose to use the GMI model to investigate the budget of Bry by modeling short-lived organic bromine compounds, including CHBr3, CH2Br2, CH2BrCl, CHBr2Cl, CHBrCl2, and C2H4Br2.  We will develop emission inventories of each gas and examine the resulting distributions of each compound individually.  We will then examine the distribution of Bry from all bromine compounds.  Comparison of modeled BrO with observations from GOME, SCIAMACHY, and in situ instruments will help us to quantify the bromine budget in both troposphere and stratosphere.  Observed seasonal, latitudinal, and interannual variability in BrO will help in validating sources. Knowledge of the sources and budgets of total bromine will be necessary to the prediction of future trends in ozone and other trace gases, as the sources of these biogenic compounds may vary with sea surface temperature and ocean productivity, leading to climatic feedbacks.

+ Back to Participant Listing