19 Nov 2020

19 Nov 2020

Review status: a revised version of this preprint was accepted for the journal TC and is expected to appear here in due course.

Sensitivity of the surface energy budget to drifting snow as simulated by MAR in coastal Adelie Land, Antarctica

Louis Le Toumelin1,2, Charles Amory1,3, Vincent Favier1, Christoph Kittel3, Stefan Hofer4, Xavier Fettweis3, Hubert Gallée1, and Vinay Kayetha5 Louis Le Toumelin et al.
  • 1Université Grenoble Alpes, CNRS, Institut des Géosciences de l’Environnement, 38000, Grenoble, France
  • 2Univ. Grenoble Alpes, Université de Toulouse, Météo-France, CNRS, CNRM, Centre d’Études de la Neige, Grenoble, France
  • 3F.R.S.-FNRS, Laboratory of Climatology, Department of Geography, University of Liège, 4000 Liège, Belgium
  • 4Department of Geosciences, University of Oslo, Oslo, Norway
  • 5Science Systems and Applications, Greenbelt, MD, USA

Abstract. In order to understand the evolution of the climate of Antarctica, dominant processes that control surface and low-atmosphere meteorology need to be accurately captured in climate models. We used the regional climate model MAR (v3.11) at 10 km horizontal resolution, forced by ERA5 reanalysis over a 9-year period (2010–2018), to study the impact of drifting snow (designing here the wind-driven transport of snow particles below and above 2 m) on the near-surface atmosphere and surface in Adelie Land, East Antarctica. Two model runs were performed, respectively with and without drifting snow, and compared to half-hourly in situ observations at D17, a coastal and windy location of Adelie Land. We show that sublimation of drifting-snow particles in the atmosphere drives the difference between model runs and is responsible for significant impacts on the near-surface atmosphere. By cooling the low atmosphere and increasing its relative humidity, drifting snow also reduces sensible and latent heat exchanges at the surface (−5.9 W m−2 on average). Moreover, large and dense drifting-snow layers act as near-surface cloud by interacting with incoming radiative fluxes, enhancing incoming longwave radiations and reducing incoming shortwave radiations in summer (net radiative forcing: 5.9 W m−2). Even if drifting snow modifies these processes involved in surface-atmosphere interactions, the total surface energy budget is only slightly modified by introducing drifting snow, because of compensating effects in surface energy fluxes. The drifting-snow driven effects are not prominent near the surface but peak higher in the boundary layer (fifth vertical level, 38 m) where drifting snow sublimation is the most pronounced. Accounting for drifting snow in MAR generally improves the comparison at D17, more especially for the representation of relative humidity (mean bias reduced from −11.1 % to 2.9 %) and incoming longwave radiation (mean bias reduced from −7.6 W m−2 to −1.5 W m−2). Consequently, our results suggest that a detailed representation of drifting-snow processes is required in climate models to better capture the near–surface meteorology and surface–atmosphere interactions in coastal Adelie Land.

Louis Le Toumelin et al.

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Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Louis Le Toumelin et al.

Data sets

Radiation data (2014-2019) at site D17 (Adelie Land, East Antarctica) Charles Amory, Louis Le Toumelin, Vincent Favier, and Christophe Genthon

Louis Le Toumelin et al.


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Short summary
Snow is frequently eroded from the surface by the wind in Adelie Land (Antarctica) and suspended in the lower atmosphere. By performing model simulations, we show firstly that suspended snow layers interact with incoming radiations similarly to a near-surface cloud. Secondly, suspended snow modify the atmosphere thermodynamic structure and energy exchanges with the surface. Our results suggest snow transport by the wind should be taken into account in future model studies over the region.