Collaborative Research: Investigation of Ozone Photochemistry in Lower Free Troposphere Continental Outflow Traveling Over the North Atlantic

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In this project, ozone (O3), NOx (NO+NO2), peroxyacetyl nitrate (PAN), non-methane hydrocarbons (NMHC), and carbon monoxide (CO) will be measured continuously over two full summers at the Pico mountain observatory in the Azores, in order to study transport events over a range of transport altitudes and pathways. To identify and attribute pollution transport events, FLEXPART particle dispersion model simulations of the transport of anthropogenic and boreal wildfire emissions to Pico will be conducted, and all events with observed anthropogenic impacts and minimal boreal fire impacts will be analyzed. Tropospheric O3, CO, and NO2 from the TES, OMI, and SCIAMACHY satellite sensors will be analyzed to assess the importance of the sampled events relative to the total column. Data will be analyzed in conjunction with GEOS-Chem chemical transport model (CTM) simulations to evaluate the ability of the CTM to simulate observed absolute and relative enhancements in measured species and to probe the consistency between observations and simulated photochemistry and mixing. New techniques will be used that combine high-resolution FLEXPART simulations with CTM output to obtain a semi-Lagrangian sampling of CTM simulations in pollution transport events. By analyzing multiple events over two summer seasons, the data will be used to quantify the contribution of such events to large-scale impacts of continental outflow on O3 and O3 precursors. This work will lead to reduced uncertainties in estimates of the impacts of anthropogenic and boreal fire emissions on tropospheric O3. It will provide new information on variability in remote lower free tropospheric O3 and PAN resulting from inter-annual variability in boreal fire activity. This project will contribute to teaching and training by providing a doctoral research topic for one graduate student as well as an undergraduate research project; through the sharing of research findings with high school teachers in the Azores; and through a web site. It will enhance research infrastructure by maintaining the Pico station during a period of transition to a permanent Global Atmosphere Watch (GAW) station. A Pico GAW station would be a valuable resource for the atmospheric science community for long-term monitoring of atmospheric composition and trans-Atlantic pollution transport, and as a base for research intensives.