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Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2019,6,4]]},"abstract":"<jats:p>\n                    The hydroxyl radical (OH) fuels tropospheric ozone production and governs the lifetime of methane and many other gases. Existing methods to quantify global OH are limited to annual and global-to-hemispheric averages. Finer resolution is essential for isolating model deficiencies and building process-level understanding. In situ observations from the Atmospheric Tomography (ATom) mission demonstrate that remote tropospheric OH is tightly coupled to the production and loss of formaldehyde (HCHO), a major hydrocarbon oxidation product. Synthesis of this relationship with satellite-based HCHO retrievals and model-derived HCHO loss frequencies yields a map of total-column OH abundance throughout the remote troposphere (up to 70% of tropospheric mass) over the first two ATom missions (August 2016 and February 2017). This dataset offers unique insights on near-global oxidizing capacity. OH exhibits significant seasonality within individual hemispheres, but the domain mean concentration is nearly identical for both seasons (1.03 \u00b1 0.25 \u00d7 10\n                    <jats:sup>6<\/jats:sup>\n                    cm\n                    <jats:sup>\u22123<\/jats:sup>\n                    ), and the biseasonal average North\/South Hemisphere ratio is 0.89 \u00b1 0.06, consistent with a balance of OH sources and sinks across the remote troposphere. Regional phenomena are also highlighted, such as a 10-fold OH depression in the Tropical West Pacific and enhancements in the East Pacific and South Atlantic. This method is complementary to budget-based global OH constraints and can help elucidate the spatial and temporal variability of OH production and methane loss.\n                  <\/jats:p>","DOI":"10.1073\/pnas.1821661116","type":"journal-article","created":{"date-parts":[[2019,5,20]],"date-time":"2019-05-20T20:24:45Z","timestamp":1558383885000},"page":"11171-11180","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":89,"title":["Mapping hydroxyl variability throughout the global remote troposphere via synthesis of airborne and satellite formaldehyde observations"],"prefix":"10.1073","volume":"116","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6586-4043","authenticated-orcid":false,"given":"Glenn M.","family":"Wolfe","sequence":"first","affiliation":[{"name":"Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, MD 21228;"},{"name":"Atmospheric Chemistry and Dynamics Laboratory, NASA 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