The evolution of atmospheric composition downwind of a city depends strongly on the concentration of OH within the plume. We use space-based observations of NO2, a molecule that affects both the sources and sinks of OH, to examine the functional dependence of OH concentration on the speed of the wind over Riyadh, Saudi Arabia. These observations illustrate the nonlinear dependence of the OH concentration on NO2 and on the rate of atmospheric mixing. We derive a range of NOx lifetimes of 5.5–8.0 h, lifetimes that correspond to an effective plume-averaged OH concentration of 7.6 × 106 molecules cm–3 at fast (26 km h–1) and 5.2 × 106 molecules cm–3 at slow (4 km h–1) wind speeds.
Variations of OH radical in an urban plume inferred from NO2 column measurements
Valin, L.C., A.R. Russell, and R.C. Cohen (2013), Variations of OH radical in an urban plume inferred from NO2 column measurements, Geophys. Res. Lett., 40, 1856-1860, doi:10.1002/grl.50267.
Abstract
PDF of Publication
Download from publisher's website
Research Program
Atmospheric Composition Modeling and Analysis Program (ACMAP)
Disclaimer: This material is being kept online for historical purposes. Though accurate at the time of publication, it is no longer being updated. The page may contain broken links or outdated information, and parts may not function in current web browsers. Visit https://espo.nasa.gov for information about our current projects.