Deposition of dinitrogen pentoxide, N₂O₅, to the snowpack at high latitudes

Abstract. Dinitrogen pentoxide, N₂O₅, is an important nighttime intermediate in the oxidation of NO_x that is hydrolysed on surfaces. We conducted a field campaign in Fairbanks, Alaska during November 2009 to measure the gradient and derive a flux (and deposition velocity) of N₂O₅ depositing to snowpack using the aerodynamic gradient method. The deposition velocity of N₂O₅ under Arctic winter conditions was found to be 0.59 ± 0.47 cm s⁻¹, which is the first measurement of this parameter to our knowledge. Based on the measured deposition velocity, we compared the chemical loss rate of N₂O₅ via snowpack deposition to the total steady state loss rate and found that deposition to snowpack is at least 1/8th of the total chemical removal of N₂O₅ that is located within the first few meters above the ground surface.