TY - JOUR
T1 - Calculations of in-snow NO and OH radical photochemical production and photolysis rates
T2 - A field and radiative-transfer study of the optical properties of Arctic (Ny-Ålesund, Svalbard) snow
AU - France, J.L.
AU - King, M.D.
AU - Lee-Taylor, J.
AU - Beine, H.J.
AU - Ianniello, A.
AU - Domine, F.
AU - MacArthur, A.
PY - 2011/12
Y1 - 2011/12
N2 - 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.
AB - 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.
KW - Arctic
KW - fluxes
KW - hydroxyl radical
KW - nitrate
KW - snowpack
UR - http://www.scopus.com/inward/record.url?scp=80052979690&partnerID=8YFLogxK
U2 - 10.1029/2011JF002019
DO - 10.1029/2011JF002019
M3 - Article
AN - SCOPUS:80052979690
VL - 116
JO - Journal of Geophysical Research F: Earth Surface
JF - Journal of Geophysical Research F: Earth Surface
IS - 4
M1 - F04013
ER -