Gaining an understanding of the sources and sinks of ozone (O3) in the troposphere and lower stratosphere is important because O3 affects the earth's radiation budget, the flux of ultraviolet…

This is a $656,849.46 grant awarded by NASA to the Regents of the University of Colorado (University of Colorado) to study the transport and scavenging of ozone precursors in convective clouds. The effort aims to build on previous NASA field campaigns, including the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and Deep Convective Clouds and Chemistry (DC3) studies. The University of Colorado, in collaboration with researchers from the National Center for Atmospheric Research and the U.S. Environmental Protection Agency, will analyze data collected during these campaigns to better understand how convective clouds impact the sources and sinks of tropospheric and lower stratospheric ozone. This research is intended to improve regional and global chemistry transport models and aid in determining upper tropospheric ozone trends, which is a key focus area for NASA's Atmospheric Composition Modeling and Analysis Program (ACMAP). The grant does not have a set-aside designation.

Gaining an understanding of the sources and sinks of ozone (O3) in the troposphere and lower stratosphere is important because O3 affects the earth's radiation budget, the flux of ultraviolet radiation to the surface, and the production of radical species that are responsible for the removal of primary pollutants. In the upper troposphere (UT), where O3 is a radiatively active trace gas, the primary sources of this gas are transport of high O3 from the stratosphere as well as transport of O3 precursors from the boundary layer followed by in situ chemical production. Chemistry involving HOX (= OH + HO2) and NOX (= no + NO2) radicals in the presence of volatile organic compounds (vocs) generally results in net ozone production. To get to the UT, these O3 precursors are often transported through convective clouds where other processes, e.g. scavenging into cloud particles and multiphase chemistry occur. In the past, our quantitative understanding of how much soluble O3 precursors, such as CH2O, H2O2, CH3OOH, and CH3OH, were removed by convective clouds was limited because of the lack of methodical air composition measurements in the inflow, outflow, and interstitial cloud regions of the convection. However, the recent NASA sponsored field campaigns SEAC4RS (studies of emissions, atmospheric composition, clouds and climate coupling by regional surveys) and DC3 (deep convective clouds and chemistry) provided invaluable airborne data to address these limitations. The PIS in their analysis of DC3 data determined significant differences in their deduced scavenging efficiencies (SES) for the above O3 precursors with those of past studies. These new findings from DC3 resulted in three publications in 2016. The three papers from DC3, which present independent methods in determining scavenging efficiencies for the above O3 precursors, determined that one of the most important aspects for high accuracy in the determination of SES is the identification of boundary layer inflow that best represents the sampled outflow in the UT. Researchers from the university of colorado (CO-PI alan fried), the national center for atmospheric research (CO-PI mary barth), and the united states environmental protection agency (CO-i nick heath) are proposing a 3-year effort applying similar analysis methods and lessons learned from DC3 to convection sampled during the 2013 SEAC4RS and, where possible, during 2016 korean-united states air quality (korus-AQ) NASA aircraft studies. These studies, particularly the SEAC4RS campaign, frequently sampled convection at various stages and at various altitudes employing a fully instrumented NASA DC-8 aircraft platform. This and the added information afforded by the onboard APR2 radar will provide significant new opportunities to study convection at various stages and potentially with different water phases. Specifically, the collaborative team herein proposes to: carefully identify coherently-related inflow and outflow sampling regions; employ various insoluble trace gases measured on the NASA DC-8 aircraft along with WRF-chem modeling in determining entrainment rates and ultimately SES for the aforementioned gases and potentially other important O3 precursors; and continue the determination of ICE retention factors. The proposing team will then employ this information to ultimately determine the resulting impact on UT O3 employing in-cloud photochemical modeling. These results will be synthesized with similar results from other NASA campaigns to produce a more universal picture of the cloud chemistry processes. Thus, the overall results from the project will benefit regional-scale and global-scale chemistry transport models by providing improved methods for representing processes affecting trace gases in convection. The improved model simulations will then allow better determination of O3 trends in the upper troposphere, which is one of the main areas of interest in NASA's acmap solicitation.