The triggering of sub-glacial lake drainage during the rapid glacier drawdown: Crane Glacier, Antarctic Peninsula

• Main Authors: Scambos, T. A., Berthier, Etienne, Shuman, C. A.
• Other Authors: National Snow and Ice Data Center (NSIDC), University of Colorado Boulder, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), NASA Goddard Space Flight Center (GSFC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Antarctic; Antarctic Peninsula; Glacial Lake; Crane Glacier; Annals of Glaciology; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-00626055; https://hal.archives-ouvertes.fr/hal-00626055/document; https://hal.archives-ouvertes.fr/hal-00626055/file/Scambos_et_al_Annals_2011.pdf

International audience Ice surface altimetry from ICESat-1 and NASA aircraft altimeter overflights spanning 2002- 09 indicate that a region of lower Crane Glacier, Antarctic Peninsula, shows an unusual temporal pattern of elevation loss: a period of very rapid drawdown ( 91 m a -1 between September 2004 and September 2005) bounded by periods of large but more moderate rates (23 m a -1 until September 2004; 12 m a -1 after September 2005). The region of increased drawdown is 4.5 km 2.2 km based on satellite (ASTER and SPOT-5) stereo-image digital elevation model (DEM) differencing spanning the event. In a later differential DEM the anomalous drawdown feature is not seen. Bathymetry in Crane Glacier fjord reveals a series of flat-lying, formerly subglacial deeps interpreted as lake sediment basins. We conclude that the elevation-change feature resulted from drainage of a small, deep subglacial lake. We infer that the drainage event was induced by hydraulic forcing of subglacial water past a downstream obstruction. However, only a fraction of Crane Glacier's increase in flow speed that occurred near the time of lake drainage (derived from image feature tracking) appears to be directly attributable to the event; instead, retreat of the ice front off a subglacial ridge 6 km downstream of the lake is likely the dominant cause of renewed fast flow and more negative mass balance in the subsequent 4 years.