New estimation of NO x snow-source on the Antarctic Plateau for a better global model parameterization

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Barbero, Albane, Savarino, J., Blouzon, C., Frey, M., Picard, G., Ahmed, S, Amory, C, Thomas, J, Huang, Y., Caillon, N., Grilli, Roberto
• Other Authors: Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), ANR-16-CE01-0011,EAIIST,Projet International d'exploration de la calotte polaire de l'Antarctique de l'Est(2016)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Model parameterization; Nitrate photolysis; Antarctic Plateau; Oxidative capacity; Flux chamber; Snowpack emissions; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Antarc*; Antarctic; Antarctica
• Online Access: https://hal.science/hal-03402244; https://hal.science/hal-03402244/document; https://hal.science/hal-03402244/file/20210224_New%20estimation%20of%20NOx%20snow_V3_ab.pdf; https://doi.org/10.1029/2021JD035062

International audience To fully decipher the role of nitrate photolysis on the atmospheric oxidative capacity in snow-covered regions, NOx flux must be determined with more precision than existing estimates. Here, we introduce a method based on dynamic flux chamber measurements for evaluating the NOx production by photolysis of snowpack nitrate in Antarctica. Flux chamber experiments were conducted for the first time in Antarctica, at the French-Italian station Concordia, Dome C (75°06'S, 123°20’E, 3233 m a.s.l) during the 2019–2020 summer campaign. Measurements were gathered with several snow samples of different ages ranging from newly formed drifted snow to 6-year-old firn. Contrary to existing literature expectations, the daily average photolysis rate coefficient, urn:x-wiley:2169897X:media:jgrd57323:jgrd57323-math-0007, did not significantly vary between differently aged snow samples, suggesting that the photolabile nitrate in snow behaves as a single-family source with common photochemical properties, where a urn:x-wiley:2169897X:media:jgrd57323:jgrd57323-math-0008 = (2.37 urn:x-wiley:2169897X:media:jgrd57323:jgrd57323-math-0009 0.35) × 10−8 s−1 (1urn:x-wiley:2169897X:media:jgrd57323:jgrd57323-math-0011) has been calculated from December 10th 2019 to January 7th 2020. At Dome C summer daily average NOx flux, urn:x-wiley:2169897X:media:jgrd57323:jgrd57323-math-0015, based on measured NOx production rates was estimated to be (4.3 urn:x-wiley:2169897X:media:jgrd57323:jgrd57323-math-0017 1.2) × 108 molecules cm−2 s−1, which is 1.5–7 times less than the net NOx flux observed previously above snow at Dome C using the gradient flux method. Using these results, we extrapolated an annual continental snow sourced NOx budget of 0.017 urn:x-wiley:2169897X:media:jgrd57323:jgrd57323-math-0022 0.003 Tgurn:x-wiley:2169897X:media:jgrd57323:jgrd57323-math-0023N y−1, urn:x-wiley:2169897X:media:jgrd57323:jgrd57323-math-00252 times the nitrogen budget, (N-budget), of the stratospheric denitrification previously estimated for ...