Calibration and validation of the CryoSat-2 radar altimeter: field studies on the Greenland Ice Sheet
Abstract
Detailed time series of ice motion data were collected from a transect at a land-terminating margin of the Greenland Ice Sheet between May 2008 and May 2013. The transect consisted of 7 GPS units extending to ~120km inland. The ice-motion data, collected in conjunction with observations of ice-sheet melt and runoff, enabled the coupling between surface melt and ice dynamics to be investigated over a variety of temporal and spatial scales. We observed that the effect of surface meltwater penetration to the ice sheet bed is to perturb the subglacial hydrology at the ice-bed interface causing the ice sheet to flow faster in summer. However, we found that during summers of extreme melt, such as in 2012 (the most extreme melt-summer observed to date on Greenland), the ice sheet at our land-terminating margin flowed more slowly than in the average melt year of 2009, due principally to slower winter flow following faster summer flow. These findings suggest that the annual motion of land-terminating margins of the ice sheet, and thus the projected dynamic contribution of these margins to sea level rise, is insensitive to melt volumes commensurate with temperature projections for 2100. Our data also revealed short-term (<30 day) surface elevation change due to hydraulic jacking of up to 0.5m magnitude. As such, satellite missions should be cautioned against using differencing in ice-sheet elevation between summer melt-seasons in order to avoid erroneous estimates of dh/dt and thus errors in mass change.
Full Report
Calibration and validation of the CryoSat-2 radar altimeter: field studies on the Greenland Ice SheetSelected external publications resulting from this GEF loan
- Tedstone, A., 2015, Hydrological controls on diurnal ice flow variability in a Greenland outlet glacier, University of Edinburgh, PhD Thesis
- Bartholomew, I., Nienow, P., Sole, A., Mair, D., Cowton,T., King, M. and Palmer, S., 2011, Seasonal variations in Greenland Ice Sheet motion: inland extent and behaviour at higher elevations, Earth and Planetary Science Letters, 307, pp271-278, doi: 10.1016/j.epsl.2011.04.014
- Sole, A., Mair, D., Nienow, P., Bartholomew, I., Cowton,T., King, M., Burke, M. and Joughin, I., 2011, Seasonal speed-up of a Greenland marine-terminating outlet glacier forced by surface melt-induced changes in subglacial hydrology, Journal of Geophysical Research, 116, F03014, doi: 10.1029/2010JF001948
- Tedstone, A.J., Nienow, P.W., Gourmelen, N. and Sole, A.J., 2014, Greenland ice sheet annual motion insensitive to spatial variations in subglacial hydraulic structure, Geophysical Research Letters, 41(24), pp8910-8917, doi: 10.1002/2014GL062386
- Cowton, T., Nienow, P., Sole, A., Bartholomew, I. and Mair, D., 2016, Variability in ice motion at a land-terminating Greenlandic outlet glacier: the role of channelized and distributed drainage systems, Journal of Glaciology, doi: 10.1017/jog.2016.36
- Sole, A., Nienow, P., Bartholomew, I., Mair, D., Cowton, T., Tedstone, A. and King, M.A., 2013, Winter motion mediates dynamic response of the Greenland Ice Sheet to warmer summers, Geophysical Research Letters, 40, pp3940-3944, doi: 10.1002/grl.50764
- Cowton, T.R., 2013, Hydrology of a land-terminating Greenlandic outlet glacier, University of Edinburgh, PhD Thesis
- Bartholomew, I., Nienow, P., Sole, A., Mair, D., Cowton,T. and King, M., 2012, Short-term variability in Greenland Ice Sheet motion forced by time-varying meltwater inputs: implications for the relationship between subglacial drainage system behaviour and ice velocity, Journal of Geophysical Research, 117, doi: 10.1029/2011JF002220
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