Publications

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2016
Fricker, HA, Siegfried MR, Carter SP, Scambos TA.  2016.  A decade of progress in observing and modelling Antarctic subglacial water systems. Philosophical Transactions of the Royal Society a-Mathematical Physical and Engineering Sciences. 374   10.1098/rsta.2014.0294   AbstractWebsite

In the decade since the discovery of active Antarctic subglacial water systems by detection of subtle surface displacements, much progress has been made in our understanding of these dynamic systems. Here, we present some of the key results of observations derived from ICESat laser altimetry, CryoSat-2 radar altimetry, Operation IceBridge airborne laser altimetry, satellite image differencing and ground-based continuous Global Positioning System (GPS) experiments deployed in hydrologically active regions. These observations provide us with an increased understanding of various lake systems in Antarctica: Whillans/Mercer Ice Streams, Crane Glacier, Recovery Ice Stream, Byrd Glacier and eastern Wilkes Land. In several cases, subglacial water systems are shown to control ice flux through the glacier system. For some lake systems, we have been able to construct more than a decade of continuous lake activity, revealing internal variability on time scales ranging from days to years. This variability indicates that continuous, accurate time series of altimetry data are critical to understanding these systems. On Whillans Ice Stream, our results from a 5-year continuous GPS record demonstrate that subglacial lake flood events significantly change the regional ice dynamics. We also show how models for subglacial water flow have evolved since the availability of observations of lake volume change, from regional-scale models of water routeing to process models of channels carved into the subglacial sediment instead of the overlying ice. We show that progress in understanding the processes governing lake drainage now allows us to create simulated lake volume time series that reproduce time series from satellite observations. This transformational decade in Antarctic subglacial water research has moved us significantly closer to understanding the processes of water transfer sufficiently for inclusion in continental-scale ice-sheet models.

2014
Siegfried, MR, Fricker HA, Roberts M, Scambos TA, Tulaczyk S.  2014.  A decade of West Antarctic subglacial lake interactions from combined ICESat and CryoSat-2 altimetry. Geophysical Research Letters. 41:891-898.   10.1002/2013GL058616   AbstractWebsite

We use CryoSat-2 interferometric satellite radar altimetry over the Mercer and Whillans ice streams, West Antarctica, to derive surface elevation changes due to subglacial lake activity at monthly resolution for the period 2010 to 2013. We validate CryoSat-2 elevation measurements, trends, and spatial patterns of change using satellite image differencing and in situ vertical movement from Global Positioning System (GPS) data. Two subglacial lake discharge events occur in the same subglacial-hydrological catchment within a 9 month period. Using GPS measurements that are spanning the gap between the Ice, Cloud, and land Elevation Satellite and Cryosat-2 missions, we cross-calibrate the two missions to establish the efficacy of CryoSat-2 altimetry to measure dynamic changes on the ice sheets.

2001
Fricker, HA, Popov S, Allison I, Young N.  2001.  Distribution of marine ice beneath the Amery Ice Shelf. Geophysical Research Letters. 28:2241-2244.   10.1029/2000gl012461   AbstractWebsite

We present a map of the marine ice accreted to the base of the Amery Ice Shelf (AIS), East Antarctica. This map is obtained by converting a Digital Elevation Model (DEM) of the AIS generated from satellite radar altimeter data to an ice thickness map, assuming hydrostatic equilibrium, and subtracting from that a second ice thickness map, derived from airborne radio-echo sounding (RES) measurements. The RES signal does not penetrate the marine ice, so the measurement is only to the meteoric-marine ice boundary, and therefore the difference between the two maps is the marine ice thickness. The marine ice is up to 190 m thick and accounts for about 9% of the shelf volume. It is concentrated in the northwest of the shelf, a result of the clockwise ocean circulation in the cavity below.

2000
Fricker, HA, Hyland G, Coleman R, Young NW.  2000.  Digital elevation models for the Lambert Glacier-Amery Ice Shelf system, East Antarctica, from ERS-1 satellite radar altimetry. Journal of Glaciology. 46:553-560.   10.3189/172756500781832639   AbstractWebsite

The Lambert Glacier-Amery Ice Shelf system is a major component of the East Antarctic ice sheet. This paper presents two digital elevation models (DEMs) that have been generated for the Lambert-Amery system from validated European Remote-sensing Satellite (ERS-1) radar altimeter waveform data. The first DEM covers the Amery Ice Shelf only, and was produced using kriging on a 1 km grid. The second is a coarser (5 km) DEM of the entire Lambert-Amery system, generated via simple averaging procedures. The DEMs provide unprecedented surface elevation information for the Lambert-Amery system and allow new insight into the glaciology of the region.