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TitleRetrieving Cryosat-2 elevations over Arctic ice caps and glaciers - A case study of Barnes ice cap
AuthorBurgess, D; Gray, L; Nilsson, J
SourceIGS Nordic Branch 2013 meeting, abstracts; by IGS Nordic Branch; 2013.
Alt SeriesEarth Sciences Sector, Contribution Series 20130297
MeetingIGS Nordic Branch Meeting 2013; Lammi; FI; October 31 - November 2, 2013
Mediadigital; on-line
File formatpdf
Subjectsgeophysics; glaciers; satellites; remote sensing; sea level fluctuations; analytical methods; Barnes ice cap
ProgramProgram Coordination - Climate Change Science, Climate Change Geoscience
LinksOnline - En direct
LinksIGS Nordic Branch 2013
AbstractThe CryoSat-2 mission was launched in 2010 to observe the Earth's Cryosphere. In contrast to previous satellite radars this mission is expected to monitor the elevation of small ice caps and glaciers, which according to IPCC will be the largest contributor to 21st century sea level rise. The aim of this study is to retrieve usable elevation over ice caps and glaciers in the Arctic region and quantify their associated errors. Cryosat is equipped with a radar altimeter (SIRAL) that over smaller ice caps and glaciers operates in the so called SARIn mode (Synthetic Aperture Radar-Interferometric). This mode determines the elevation and position of the surface return echo using the measured differential phase of its two antennas to estimate the cross-track look angle and thereby estimate the position of the point-of-closest-approach (POCA). In this study, surface elevation values over the Barnes ice cap were derived from CryoSat-2 data for March, April and May, 2011. The Barnes ice cap was chosen due to extensive validation data flown by NASA's IceBridge ATM-mission in May 2011. Surface elevation values derived from CryoSat-2 were determined using a maximum gradient retracker applied on 20 Hz L1B waveforms, to estimate the position of the POCA. The location of the surface return echo was mapped using the differential phase and corrected for possible phase unwrapping errors using an external digital elevation model. The derived results from this study shows agreement with the NASA - ATM measured elevations to -0.52±0.74 m, with a insignificant slope error. Crossover residuals estimated from ascending versus descending sub-satellite tracks from the estimated POCA-locations showed a 0.16±1.37 m bias. Future work will include extending this processing to include the whole Canadian Arctic to produce elevation changes. Also, an investigation will be undertaken to test the applicability of SWATH mode processing to complement POCA-measurement in higher slope regions.
Summary(Plain Language Summary, not published)
The CryoSat-2 radar altimeter is a European Space Agency initiative that will play an integral role in Canada's scaled glacier-climate observing approach, contributing to Climate Change Geoscience Program objectives through provision of data on glacier mass change as it concerns freshwater flux to oceans. Preliminary results of the L1b SARin processed data from the Devon ice cap, Nunavut reveal strong potential for Cryosat-2 to provide high spatial and temporal elevation data over small polar ice caps characteristic of those in Canada¿s high Arctic.