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TitleMeasuring height change around the periphery of the Greenland Ice Sheet with radar altimetry
AuthorGray, L; Burgess, DORCID logo; Copland, L; Langley, K; Gogineni, P; Paden, J; Leuschen, C; van As, D; Fausto, R; Joughin, I; Smith, B
SourceFrontiers in Earth Science vol. 7, 146, 2019 p. 1-14, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190144
PublisherFrontiers Media SA
Mediaon-line; digital
File formatpdf (Adobe® Reader®); html
AreaGreenland Ice Sheet; Upernavik Glacier; Greenland; Denmark
Lat/Long WENS -75.0000 -15.0000 84.0000 60.0000
Subjectshydrogeology; surficial geology/geomorphology; environmental geology; Nature and Environment; Science and Technology; geophysics; glaciology; glaciers; ice sheets; remote sensing; satellite imagery; radar methods; ice; climate effects; meteorology; snow; Climate change; synthetic aperture radar surveys (SAR)
Illustrationslocation maps; geoscientific sketch maps; time series; plots; profiles
ProgramGSC Atlantic Division
Released2019 06 11
AbstractIce loss measurements around the periphery of the Greenland Ice Sheet can provide key information on the response to climate change. Here we use the excellent spatial and temporal coverage provided by the European Space Agency (ESA) CryoSat satellite, together with NASA airborne Operation IceBridge and automatic weather station data, to study the influence of changing conditions on the bias between the height estimated by the satellite radar altimeter and the ice sheet surface. Surface and near-surface conditions on the ice sheet periphery change with season and geographic position in a way that affects the returned altimeter waveform and can therefore affect the estimate of the surface height derived from the waveform. Notwithstanding the possibility of a varying bias between the derived and real surface, for the lower accumulation regions in the western and northern ice sheet periphery (<\'181 m snow accumulation yearly) we show that the CryoSat altimeter can measure height change throughout the year, including that associated with ice dynamics, summer melt and winter accumulation. Further, over the 9-year CryoSat lifetime it is also possible to relate height change to change in speed of large outlet glaciers, for example, there is significant height loss upstream of two branches of the Upernavik glacier in NW Greenland that increased in speed during this time, but much less height loss over a third branch that slowed in the same time period. In contrast to the west and north, winter snow accumulation in the south-east periphery can be 2-3 m and the average altimeter height for this area can decrease by up to 2 m during the fall and winter when the change in the surface elevation is much smaller. We show that vertical downward movement of the dense layer from the last summer melt, coupled with overlying dry snow, is responsible for the anomalous altimeter height change. However, it is still possible to estimate year-to-year height change measurements in this area by using data from the late-summer to early fall when surface returns dominate the altimeter signal.
Summary(Plain Language Summary, not published)
Recent climate warming has enhanced melting of the Greenland ice sheet resulting in increased contributions to global sea-level rise. Due to the large areas of ice cover affected by the higher rates of summer melting, the use of satellite technology is essential for measuring such changes. In this study, the CryoSat-2 radar altimeter is used to measure changes in ice thickness around the periphery of the Greenland Ice Sheet from 2010 to 2018. Results indicate that thickness changes in some areas in west Greenland exceed 8 m over the period of study, with changes in ice dynamics as well as surface melting being responsible for the changes observed. This study demonstrates that the SARin mode of the CryoSat-2 radar altimeter provides the most reliable, accurate and timely instrument to measure continental scale glacier change currently available.

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