High-resolution modelling of the Antarctic surface mass balance, application for the twentieth, twenty first and twenty second centuries

• Published in: Climate Dynamics
• Main Authors: Agosta, Cécile, Favier, Vincent, Krinner, Gerhard, Gallée, Hubert, Fettweis, Xavier, Genthon, Christophe
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science & Business Media B.V. 2013
• Subjects: Downscaling; surface mass balance; surface energy balance; Orographic precipitation; Antarctica; Sea-level; Climate-change; ice-sheet; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Antarc*; Antarctic; Ice Sheet
• Online Access: https://orbi.uliege.be/handle/2268/143909; https://doi.org/10.1007/s00382-013-1903-9

peer reviewed About 75% of the Antarctic surface mass gain occurs over areas below 2000 m asl, which cover 40% of the grounded ice-sheet. As the topography is complex in many of these regions, SMB modelling is highly dependent on resolution, and studying the impact of Antarctica on the future rise in sea level requires physical approaches. We have developed a low time consuming, physical downscaling model for high-resolution (15 km) long-term surface mass balance (SMB) projections. Here, we present results of this model, called SMHiL (surface mass balance high-resolution downscaling), which was forced with the LMDZ4 atmospheric general circulation model to assess SMB variation in the 21st and the 22nd centuries under two different scenarios. The higher resolution of SMHiL better reproduces the geographical patterns of SMB and increase significantly the averaged SMB over the grounded ice-sheet for the end of the 20th century. A comparison with more than 3200 quality-controlled field data shows that LMDZ4 and SMHiL compare the observed values equally well. Nevertheless, field data below 2000 m asl are too scarce to efficiency show the interest of SMHiL and measuring the SMB in these undocumented areas should be then a future scientific priority. Our results suggest that running LMDZ4 at a finer resolution (15km) may give a future increase in SMB in Antarctica about 30% higher than by using its standard resolution (60 km) due to higher increase in precipitation in the coastal areas at 15 km. However, a part (~ 15%) of these discrepancies could be an artefact from SMHiL since it neglects the foehn effect and then likely overestimates the precipitation increase. Future changes in the Antarctic SMB at low elevations will result from the conflict between higher snow accumulation and runoff. For this reason, developing downscaling models is crucial to represent processes in sufficient detail and correctly model the SMB in the coastal areas.