Calculations of in-snow NO and OH radical photochemical production and photolysis rates:A field and radiative-transfer study of the optical properties of Arctic (Ny-Ålesund, Svalbard) snow

• Published in: Journal of Geophysical Research
• Main Authors: France, J.L., King, M.D., Lee-Taylor, J., Beine, H.J., Ianniello, A., Domine, F., MacArthur, A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2011
• Subjects: Arctic; Ny-Ålesund; Svalbard; Ny Ålesund
• Online Access: https://ueaeprints.uea.ac.uk/id/eprint/52685/; https://doi.org/10.1029/2011JF002019

Depth-integrated production rates of OH radicals and NO molecules from snowpacks in Ny-Ålesund, Svalbard, are calculated from fieldwork investigating the light penetration depth (e-folding depth) and nadir reflectivity of snowpacks during the unusually warm spring of 2006. Light penetration depths of 8.1, 11.3, 5.1, and 8.2 cm were measured for fresh, old, marine-influenced, and glacial snowpacks, respectively (wavelength 400 nm). Radiative-transfer calculations of the light penetration depths with reflectivity measurements produced scattering cross sections of 5.3, 9.5, 20, and 25.5 m kg and absorption cross sections of 7.7, 1.4, 3.4, and 0.5 cm kg for the fresh, old, marine-influenced, and glacial snowpacks, respectively (wavelength 400 nm). Photolysis rate coefficients, J, are presented as a function of snow depth and solar zenith angle for the four snowpacks for the photolysis of H O and NO. Depth-integrated production rates of hydroxyl radicals are 1270, 2130, 950, and 1850 nmol m h (solar zenith angle of 60°) for fresh, old, marine-influenced, and glacial snowpacks, respectively. Depth-integrated production rates of NO are 32, 56, 11, and 22 nmol m h (solar zenith angle of 60°) for the fresh, old, marine-influenced, and glacial snowpacks, respectively. The uncertainty of repeated light penetration depth measurement was determined to be ∼20%, which propagates into a 20% error in depth-integrated production rates. A very simple steady state hydroxyl radical calculation demonstrates that a pseudo first-order loss rate of OH radicals of ∼10-10 s is required in snowpack. The snowpacks around Ny-Ålesund are thick enough to be considered optically infinite.