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France J L, Reay H J, King M D, Voisin D, Jacobi H W, Domine F, Beine H, Anastasio C, MacArthur A, Lee-Taylor J,. (2012). Hydroxyl radical and NOx production rates, black carbon concentrations and light-absorbing impurities in snow from field measurements of light penetration and nadir reflectivity of onshore and offshore coastal Alaskan snow. J. Geophys. Res., 117, D00R12 ST -.
Abstract: Photolytic production rates of NO, NO2 and OH radicals in snow and the total absorption spectrum due to impurities in snowpack have been calculated for the Ocean-Atmosphere-Sea-Ice-Snowpack (OASIS) campaign during Spring 2009 at Barrow, Alaska. The photolytic production rate and snowpack absorption cross-sections were calculated from measurements of snowpack stratigraphy, light penetration depths (e-folding depths), nadir reflectivity (350–700 nm) and UV broadband atmospheric radiation. Maximum NOx fluxes calculated during the campaign owing to combined nitrate and nitrite photolysis were calculated as 72 nmol m-2 h-1 for the inland snowpack and 44 nmol m-2 h-1 for the snow on sea-ice and snowpack around the Barrow Arctic Research Center (BARC). Depth-integrated photochemical production rates of OH radicals were calculated giving maximum OH depth-integrated production rates of ~160 nmol m-2 h-1 for the inland snowpack and ~110–120 nmol m-2 h-1 for the snow around BARC and snow on sea-ice. Light penetration (e-folding) depths at a wavelength of 400 nm measured for snowpack in the vicinity of Barrow and snow on sea-ice are ~9 cm and 14 cm for snow 15 km inland. Fitting scaled HULIS (HUmic-LIke Substances) and black carbon absorption cross-sections to the determined snow impurity absorption cross-sections show a “humic-like” component to snowpack absorption, with typical concentrations of 1.2–1.5 μgC g-1. Estimates of black carbon concentrations for the four snowpacks are ~40 to 70 ng g-1 for the terrestrial Arctic snowpacks and ~90 ng g-1 for snow on sea-ice.
Keywords: Barrow OH black carbon e-folding depth nitrate photochemistry 0736 Cryosphere: Snow (1827, 1863) 0770 Cryosphere: Properties 0798 Cryosphere: Modeling (1952, 4316),
Programme: 1017
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