A32F-06
Source attribution of interannual variability of tropospheric ozone over the southern hemisphere
Wednesday, 16 December 2015: 11:35
3010 (Moscone West)
Junhua Liu1, Jose M Rodriguez2, Jennifer A Logan3, Stephen D Steenrod4, Anne R Douglass5, Mark A Olsen6, Krzysztof Wargan7 and Jerald R Ziemke2, (1)Universities Space Research Association Greenbelt, Greenbelt, MD, United States, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)Harvard Univ, Cambridge, MA, United States, (4)USRA GESTAR, Greenbelt, MD, United States, (5)NASA Goddard SFC, Greenbelt, MD, United States, (6)Morgan State University, Baltimore, MD, United States, (7)Science Systems and Applications, Inc., Lanham, MD, United States
Abstract:
Both model simulations and GMAO assimilated ozone product derived from OMI/MLS show a high tropospheric ozone column centered over the south Atlantic from the equator to 30S. This ozone maximum extends eastward to South America and the southeast Pacific; it extends southwestward to southern Africa, south Indian Ocean. In this study, we use hindcast simulations from the GMI model of tropospheric and stratospheric chemistry, driven by assimilated MERRA meteorological fields, to investigate the factors controlling the interannual variations (IAV) of this ozone maximum during the last two decades. We also use various GMI tracer diagnostics, including a stratospheric ozone tracer to tag the impact of stratospheric ozone, and a tagged CO tracer to track the emission sources, to ascertain the contribution of difference processes to IAV in ozone at different altitudes, as well as partial columns above different pressure level. Our initial model analysis suggests that the IAV of the stratospheric contribution plays a major role on in the IAV of the upper tropospheric ozone and explains a large portion of variance during its winter season. Over the south Atlantic region, the IAV of surface emissions from both South America and southern Africa also contribute significantly to the IAV of ozone, especially in the middle and lower troposphere
