Mapping hydroxyl variability throughout the global remote troposphere via...

The core information for this publication's citation.: 
Wolfe, G. M., J. Nicely, J. M. St. Clair, T. F. Hanisco, J. Liao, L. D. Oman, W. H. Brune, D. Miller, A. Thames, G. G. Abad, T. B. Ryerson, C. Thompson, J. Peischl, K. McKain, C. Sweeney, P. Wennberg, M. Kim, J. D. Crounse, S. R. Hall, K. Ullmann, G. S. Diskin, T. P. Bui, C. Chang, and J. Dean-Day (2019), Mapping hydroxyl variability throughout the global remote troposphere via synthesis of airborne and satellite formaldehyde observations, Proc. Natl. Acad. Sci., doi:10.1073/pnas.1821661116.

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-tohemispheric 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 ± 0.25 × 106 cm−3), and the biseasonal average North/South Hemisphere ratio is 0.89 ± 0.06, consistent with a balance of OH sources and sinks across the remote troposphere. Regional phenomena are also highlighted, such as a 10fold 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.

PDF of Publication: 
Download from publisher's website.
Research Program: 
Atmospheric Composition
Tropospheric Composition Program (TCP)