Oceanic Controls on the Mass Balance of Wilkins Ice Shelf, Antarctica

• Main Authors: Padman, Laurie, Costs, Daniel P., Dinniman, M. S., Fricker, Helen A., Goebel, Michael E., Huckstadt, Luis A., Humbert, Angelika, Joughin, Ian, Lenaerts, Jan T. M., Ligtenberg, Stefan R. M., Scambos, Ted, van den Broeke, Michiel R.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: ODU Digital Commons 2012
• Subjects: Climate change; Peninsula continental shelf; Digital elevation model; Sea ice; Satellite radar; Spatiotemporal variability; Elephant seals; Oceanography and Atmospheric Sciences and Meteorology; Antarctic; Antarctic Peninsula; Pine Island Glacier; Wilkins; Wilkins Ice Shelf; Antarc*; Antarctica; Elephant Seals; Ice Shelf; Ice Shelves; Pine Island
• Online Access: https://digitalcommons.odu.edu/ccpo_pubs/18; https://digitalcommons.odu.edu/cgi/viewcontent.cgi?article=1016&context=ccpo_pubs

Several Antarctic Peninsula (AP) ice shelves have lost significant fractions of their volume over the past decades, coincident with rapid regional climate change. Wilkins Ice Shelf (WIS), on the western side of the AP, is the most recent, experiencing a sequence of large calving events in 2008 and 2009. We analyze the mass balance for WIS for the period 1992-2008 and find that the averaged rate of ice-shelf thinning was similar to 0.8 m a(-1), driven by a mean basal melt rate of < w(b)> = 1.3 +/- 0.4 m a(-1). Interannual variability was large, associated with changes in both surface mass accumulation and < w(b)>. Basal melt rate declined significantly around 2000 from 1.8 +/- 0.4 m a(-1) for 1992-2000 to similar to 0.75 +/- 0.55 m a(-1) for 2001-2008; the latter value corresponding to approximately steady-state ice-shelf mass. Observations of ocean temperature T obtained during 2007-2009 by instrumented seals reveal a cold, deep halo of Winter Water (WW; T approximate to - 1.6 degrees C) surrounding WIS. The base of the WW in the halo is similar to 170 m, approximately the mean ice draft for WIS. We hypothesize that the transition in < w(b)> in 2000 was caused by a small perturbation (similar to 10-20 m) in the relative depths of the ice base and the bottom of the WW layer in the halo. We conclude that basal melting of thin ice shelves like WIS is very sensitive to upper-ocean and coastal processes that act on shorter time and space scales than those affecting basal melting of thicker West Antarctic ice shelves such as George VI and Pine Island Glacier.