Contribution of blowing snow sublimation to the surface mass balance of Antarctica

Blowing snow transport is an essential polar boundary layer process and constitutes the major ablation term in the Antarctic ice sheet's surface mass balance (SMB). Here, we present an update to the blowing snow model in the Regional Atmospheric Climate Model (RACMO), version 2.3p3, to include the effect of blowing snow sublimation and transport in the prognostic equations for temperature and water vapour. Updates rectify the numerical artefacts in the modelled blowing snow flux variation with wind speed. Updates include the replacement of uniformly distributed ice particle radius, which limited the maximum ice particle radius to ≤ 50 μm, with an exponentially increasing ice particle radius distribution to include all the relevant range of radii between 2 to 300 μm without any additional computational overhead. We compare the model results against the observations from site D47 in Adèlie Land, East Antarctica. These updates correct the numerical artefacts observed in the previous model results, and RACMO successfully predicts the power-law variation of the blowing snow transport flux with wind speed. Updates also improve the prediction of the magnitude of the blowing snow fluxes. In addition, at site D47, we obtain an average blowing snow layer depth of 230±116 μm, which falls within the range of values obtained from satellite observations. A qualitative comparison of the simulated blowing snow frequency from RACMO with CALIPSO satellite observations shows that the simulated frequency matches well with the satellite product. Compared to the previous model version for the period 2000–2010, the contribution of integrated blowing snow sublimation is increased by 30%, with a yearly average of 176±4 Gt yr-1. The increase amounts to 1.2% reduction in the integrated SMB of the Antarctic ice sheet. The updates also introduce changes in the climatology of blowing snow in Antarctica. Specifically, we observe significant changes in the sublimation of interior regions of the escarpment zone of Antarctica.