Seminar Ozean, Eis, Atmosphäre
University of Bremen, Building NW1, N3380
Date: 16.12.2003
Speaker: T. Kunhikrishnan (MPI)
Title: Inter-annual variability of Tropospheric NO2 column over Central Indian Ocean and their scaled sensitivity to continental emissions.In this study we identify recurring plumes of tropospheric NO2 during the monsoon transition periods over the Central Indian Ocean (CIO, 5N-30S, 55E-95E) based on GOME satellite observations and global model (MATCH-MPIC) simulations. The plumes originate from both Africa and Indonesia. Model sensitivity tests indicate that NOx over CIO is mainly sensitive to emissions from Africa and Indonesia especially during the monsoon transition periods. Despite the relatively short lifetime of NOx (one to a few days), these strong plumes can develop due to the pronounced anti-cyclonic circulation over CIO that slopes north-eastward with height and the shallow maritime convection, which limits vertical mixing. Model results indicate that the plumes are mainly transported in the middle troposphere. Thus, our results suggest that the CIO in the Southern Hemisphere is not always as pristine as found during INDOEX and is polluted by these recurring semi-annual plumes.
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