The distribution of ozone, water vapor, carbon dioxide and aerosols in the lower atmosphere are strongly influenced by transport. Quantifying this transport is central to understanding and predicting air quality, climate change, and stratospheric ozone depletion. This collaborative project will use a combination of trace gas measurements and model simulations. The effort will also promote training and learning of graduate students a a postdoctoral fellow. Material from this research. Materials from the research will be included in a core course for the Johns Hopkins University (JHU) Integration of Graduate Education and Research Training (IGERT) program on Water, Climate and Health, as well as teacher training courses at JHU and Columbia University. The results of the research will be widely disseminated at international science meetings, publishing in peer-reviewed journals, and posts of non-technical reports on websites.
A particularly important quantity is the transit-time distribution (TTD) for transport from Northern Hemisphere populated regions, where there are large emissions of pollutants and their precursors. Maximum entropy inversions will used together with surface and aircraft trace gas measurements to constrain the TTDs. These data-constrained TTDs will be combined with chemical transport model simulations and meteorological analyses to examine seasonal and interannual variations, and connections with atmospheric dynamics. Chemistry climate model integrations will be used to explore how the transport changes with climate.
Specifically, this project will provide the following: (1) data-constrained estimates of the TTDs since air was last in contact with Northern Hemisphere continental regions, including seasonal and interannual variations; (2) knowledge of the key dynamical controls on tropospheric transport timescales; and (3) an understanding of how tropospheric transport may change in response to climate. In combination these will allow a fundamental disentangling of the roles of chemistry and transport in shaping the composition of the troposphere, with important implications for understanding of air quality, climate change, and stratospheric ozone.
