Calculations of in-snow NO₂ and OH radical photochemical production and photolysis rates: A field and radiative-transfer study of the optical properties of Arctic (Ny-à lesund, Svalbard) snow

Depth-integrated production rates of hydroxyl radicals are 1270, 2130, 950, and 1850 nmol m⁻² h⁻¹ (solar zenith angle of 60°) for fresh, old, marine-influenced, and glacial snowpacks, respectively. Depth-integrated production rates of NO₂ are 32, 56, 11, and 22 nmol m⁻² h⁻¹ (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 ~10²-10⁴ s⁻¹ is required in snowpack. The snowpacks around Ny-à lesund are thick enough to be considered optically infinite.