Preprints
https://doi.org/10.5194/tc-2023-46
https://doi.org/10.5194/tc-2023-46
22 Mar 2023
 | 22 Mar 2023
Status: a revised version of this preprint is currently under review for the journal TC.

Foehn Winds at Pine Island Glacier and their role in Ice Changes

Diana Francis, Ricardo Fonseca, Kyle S. Mattingly, Stef Lhermitte, and Catherine Walker

Abstract. Pine Island Glacier (PIG) has recently experienced increased ice loss mostly attributed to basal melt and ocean-ice dynamics. However, atmospheric forcing also plays a role in the ice mass budget, as besides lower-latitude warm air intrusions, the steeply sloping terrain that surrounds the glacier promotes frequent Foehn winds. An investigation of 41-years of reanalysis data reveals that Foehn occurs more frequently from June to October, with Foehn episodes typically lasting about 5 to 9 h. An analysis of the surface mass balance indicated that their largest impact is on the surface sublimation, which is increased by about 1.4 mm water equivalent (w.e.) day−1 with respect to no-Foehn events. Blowing snow makes roughly the same contribution as snowfall, around 0.34–0.36 mm w.e. day−1, but with the opposite sign. The melting rate is three orders of magnitude smaller than the surface sublimation rate. The negative phase of the Antarctic Oscillation and the positive phase of the Southern Annular Mode promote the occurrence of Foehn at PIG. A particularly strong event took place on 09–11 November 2011, when 10-m winds speeds in excess of 20 m s−1 led to downward sensible heat fluxes higher than 75 W m−2 as they descended the mountainous terrain. Surface sublimation and blowing snow sublimation dominated the surface mass balance, with magnitudes of up to 0.13 mm w.e. hr−1. Satellite data indicated an hourly surface melting area exceeding 100 km2. Our results stress the importance of the atmospheric forcing on the ice mass balance at PIG.

Diana Francis et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2023-46', Anonymous Referee #1, 23 Apr 2023
    • AC1: 'Reply on RC1', Diana Francis, 19 May 2023
  • RC2: 'Comment on tc-2023-46', Anonymous Referee #2, 25 Apr 2023
    • AC2: 'Reply on RC2', Diana Francis, 19 May 2023

Diana Francis et al.

Diana Francis et al.

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Short summary
Role of Foehn Winds in ice and snow conditions at the Pine Island Glacier – Antarctica