1-D Air-snowpack modeling of atmospheric nitrous acid at South Pole during ANTCI 2003 W. Liao and D. Tan Georgia Institute of Technology, Earth and Atmospheric Sciences Department, 311 Ferst Dr. Atlanta, GA 30332, USA
Abstract. A 1-D air-snowpack model of HONO has been developed and constrained by
observed chemistry and meteorology data. The 1-D model includes molecular
diffusion and mechanical dispersion, windpumping in snow, gas phase to
quasi-liquid layer phase HONO transfer and quasi-liquid layer nitrate and
interstitial air HONO photolysis. Photolysis of nitrate is important as a
dominant HONO source inside the snowpack, however, the observed HONO
emission from the snowpack was triggered mainly by the equilibrium between
quasi liquid layer nitrite and firn air HONO deep down the snow surface (i.e. 30 cm
below snow surface). The high concentration of HONO in the firn air is
subsequently transported above the snowpack by diffusion and windpumping.
The model uncertainties come mainly from lack of measurements and the
interpretation of the QLL properties based on the bulk snow measurements.
One critical factor is the ionic strength of QLL nitrite, which is estimated
here by the bulk snow pH, nitrite concentration, and QLL to bulk snow volume
Citation: Liao, W. and Tan, D.: 1-D Air-snowpack modeling of atmospheric nitrous acid at South Pole during ANTCI 2003, Atmos. Chem. Phys., 8, 7087-7099, doi:10.5194/acp-8-7087-2008, 2008.