Measurements of NO x emissions from the Antarctic snowpack

It has been shown that NO x is produced photochemically within the snowpack of polar regions. If emitted to the atmosphere, this process could be a major source of NO x in remote snowcovered regions. We report here on measurements made at the German Antarctic station, Neumayer, during austral summer 1999, aimed at detecting and quantifying emissions of NO x from the surface snow. Gradients of NO x measured, and fluxes calculated using local meteorology measurements. On the 2 days of flux measurements, the derived fluxes showed continual release from the snow surface, varying between ∼0 and 3 × 10 8 molecs/cm²/s. When not subject to turbulence, the variation was coincident with the uv diurnal cycle, suggesting rapid release once photochemically produced. Scaling the diurnal average of Feb. 7th (1.3 × 10 8 molecs/cm²/s) suggests an annual emission over Antarctica of the order 0.0076TgN.