Formaldehyde (HCHO) in air, snow, and interstitial air at Concordia (East Antarctic Plateau) in summer

Abstract : During the 2011/12 and 2012/13 austral summers , HCHO was investigated for the first time in ambient air, snow, and interstitial air at the Concordia site, located near Dome C on the East Antarctic Plateau, by deploying an Aerolaser AL-4021 analyzer. Snow emission fluxes were estimated from vertical gradients of mixing ratios observed at 1 cm and 1 m above the snow surface as well as in interstitial air a few centimeters below the surface and in air just above the snowpack. Typical flux values range between 1 and 2 × 1012 molecules m-2 s-1 at night and 3 and 5 × 1012 molecules m-2 s-1 at noon. Shading experiments suggest that the photochemical HCHO production in the snowpack at Concordia remains negligible compared to temperature-driven air–snow exchanges. At 1 m above the snow surface, the observed mean mixing ratio of 130 pptv and its diurnal cycle characterized by a slight decrease around noon are quite well reproduced by 1-D simulations that include snow emissions and gas-phase methane oxidation chemistry. Simulations indicate that the gas-phase production from CH4 oxidation largely contributes (66 %) to the observed HCHO mixing ratios. In addition, HCHO snow emissions account for ∼ 30 % at night and ∼ 10 % at noon to the observed HCHO levels.
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Suzanne Preunkert, Michel Legrand, Markus Frey, Alexandre Kukui, Joël Savarino, et al.. Formaldehyde (HCHO) in air, snow, and interstitial air at Concordia (East Antarctic Plateau) in summer. Atmospheric Chemistry and Physics, European Geosciences Union, 2015, 15 (12), pp.6689-6705. ⟨10.5194/acp-15-6689-2015⟩. ⟨hal-01164674⟩

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