Measurements of NO_x emissions from the Antarctic snowpack

Abstract

Abstract.It has been shown that NOs is produced photochemically within the snowpack of polar regions. If emitted to the atmosphere, this process could be a major source of NOs 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• from the surface snow. Gradients of NOs were 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 3x108 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(1.3x108 molecs/cm2/s) suggests an annual emission over Antarctica of the order 0.0076TgN.

Tropospheric NO<sub>2</sub> columns: a comparison between model and retrieved data from GOME measurements

“…The production of NO 2 in or just above snow is believed to result from the photolysis of HNO 3 carried to the Antarctic in the snow (e.g. Jones et al, 2001). This cycling mechanism is certainly not in the model yet, but the differential signal may be seen by GOME.…”

Modelling the physical multiphase interactions of HNO<sub>3</sub> between snow and air on the Antarctic Plateau (Dome C) and coast (Halley)

“…Emissions of nitrogen oxides, NO x = NO + NO 2 , from snow to the overlying air as a result of photolysis of the nitrate anion, NO − 3 , within snow have been observed in polar (Jones et al, 2001;Beine et al, 2002) and midlatitude regions (Honrath et al, 2000). They were found to have a significant impact on the oxidising capacity of the atmospheric boundary layer, especially in remote areas, such as the polar regions, where anthropogenic pollution is small (Grannas et al, 2007).…”

Iodine monoxide in the Antarctic snowpack

“…Nitrate and MSA formation are both dependent on photolytic processes, with MSA being a product of dimethyl sulphide oxidation by OH radicals during abstraction and addition oxidation pathways (von Glasow and Crutzen, 2004). It is thought that most of the nitrate excess (compared to background winter levels) observed during spring and summer originates from sedimentation from the stratosphere, and to a lesser degree (and perhaps latter in the summer season) from photolytic release of nitrate from the snow pack (Wagenbach et al, 1998;Jones et al, 2001;Weller et al, 2004;Savarino et al, 2007). Thus these three independent indicators should give a reliable representation of summer/winter stratification in the snow pit, and can be clearly seen in Fig.…”