Measurements of NOx emissions from the Antarctic snowpack

It has been shown that NOx is produced photochemically within the snowpack of polar regions. If emitted to the atmosphere, this process could be a maj or source of NOx in remote snowcovered regions. We report here on measureme nts made at the German Antarctic station, Neumayer, during austral summer 1 999, aimed at detecting and quantifying emissions of NOx from the surface s now. Gradients of NOx were measured, and fluxes calculated using local mete orology measurements. On the 2 days of flux measurements, the derived fluxe s showed continual release from the snow surface, varying between similar t o0 and 3x10(8) molecs/cm(2)/s. When not subject to turbulence, the variatio n was coincident with the uv diurnal cycle, suggesting rapid release once p hotochemically produced. Scaling the diurnal average of Feb. 7th (1.3x10(8) molecs/cm(2)/s) suggests an annual emission over Antarctica of the order 0 .0076TgN.