- Related Research Areas
- Atmospheric Composition, Climate Variability & Change
We propose analyses of Aura and SCISAT satellite data and Global Modeling Initiative (GMI) simulations that will increase our understanding of stratospheric transport processes and reduce the uncertainties in predictions of the stratospheric ozone response to changes in atmospheric composition. This proposal is relevant to MAP because it addresses improvement of our ability to predict future changes to the Earth system through modeling and the analysis of satellite data. Its goals include understanding processes that control the chemical and radiative balance of the UT/LS and understanding how stratospheric processes affect climate. The studies fall broadly into two categories: satellite trace gas data analyses, and chemistry and transport model (CTM) experiments. The satellite data analyses will investigate 1) mass exchange between the tropical upper troposphere/lower stratosphere and the extratropics, 2) cross-tropopause transport from the lowermost stratosphere, and 3) mixing into the tropical pipe, its interannual and QBO variations, and how these processes are connected to polar composition. The CTM experiments are multi-year integrations of the GMI CTM with “Combo” chemistry using both general circulation model and assimilated meteorological fields. Model analyses will address issues such as resolution requirements for realistic representation of various atmospheric processes. The understanding of the important processes that we gain from satellite data analyses will be used to evaluate the representation of those processes in GMI simulations. GMI will integrate a multi-decadal tropospheric “hindcast” experiment that supports IGAC Atmospheric Chemistry and Climate modeling activities. The purpose of the hindcast is to determine if we understand the processes controlling the observed changes in tropospheric composition, especially O3, during the late 20th century. We will evaluate long-term behavior of lower stratospheric O3 in a GMI-Combo hindcast simulation (“GMI-MERRA”). The evaluation will use existing diagnostics of UT/LS transport, long-term O3 data sets, and satellite and aircraft campaign O3 and trace gas data from 1987 to the present. The focus of the GMI-MERRA evaluation will be to assess the credibility of its long-term O3 simulation with regard to trend analyses and transport of stratospheric ozone to the troposphere. We have reached a point in the evaluation of models where we must ask whether our use of the diagnostics is telling us what we need to know. That is, do the diagnostics distinguish between the models based on their physical behavior? Are these diagnostics helping to reduce the uncertainties in chemistry-climate simulations? We will investigate how to judiciously apply the diagnostics we have, and identify and prioritize processes required for a credible simulation. The goal is to develop an integrated evaluation of stratospheric transport in chemistry climate models.
Project PI: Susan Strahan/University of Maryland Baltimore County
Atmospheric Chemistry and Dynamics Building 33, Room E317 NASA GSFC, Code 613.3 Greenbelt, MD 20771 USA
Phone: (301) 614-5995
Fax: (301) 614-5903
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