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dc.contributor.advisorSchutz, Bob E.
dc.creatorFelikson, Denisen
dc.date.accessioned2014-04-22T20:40:05Zen
dc.date.issued2013-12en
dc.date.submittedDecember 2013en
dc.identifier.urihttp://hdl.handle.net/2152/24087en
dc.descriptiontexten
dc.description.abstractThis report compares surface elevation change and volume change esti- mates from three methods: repeat track (RT), crossover (CX), and overlapping footprints (OFP). These three methods use different approaches to group- ing elevation point measurements taken at different measurement epochs and estimating elevation change. Volume changes are calculated from elevation changes in the same manner for all three methods but differences in sampling resolution between the methods affect volume change estimates in different ways. The recently reprocessed Release 633 version of elevation measurements from the Geoscience Laser Altimeter System (GLAS), flown on the Ice, Cloud and land Elevation Satellite (ICESat), are used in this analysis. Both elevation changes and volume changes are compared for both the Greenland Ice Sheet (GrIS) and the Antarctic Ice Sheet (AIS). Additionally, uncertainties in the estimates for each method are quantified and compared. Results are separated by drainage systems and by above/below 2000 m surface elevation for the GrIS. For the AIS, results are aggregated to the East, West, and Penin- vi sula regions. Volume change estimates agree well for the three methods for the GrIS, with estimates of -227.75 ± 2.12 km³/yr, -249.30 ± 3.42 km³/yr, and -218.24 ± 7.39 km³/yr for the RT, CX, and OFP methods, respectively. These estimates are similar to those published from previous studies. For the AIS, however, larger discrepancies are found in the estimates. This stems primarily from a large discrepancy in the volume change estimate of the East AIS, where the RT, CX, and OFP methods estimate volume changes of 33.39 ± 1.42 km³/yr, 46.42 ± 5.46 km³/yr, and -2.72 ± 2.12 km³/yr, respectively. It's not entirely clear why this large discrepancy exists in this particular region, and elevation change estimates for a few particular drainage systems in this region are examined. Previously published volume changes for the AIS also show a large scatter and more work must be done to reconcile the various estimates. Finally, the volume change uncertainties reported do not completely account for the discrepancies in most regions. Additional analysis must be done to completely quantify all error sources.en
dc.format.mimetypeapplication/pdfen
dc.subjectICESaten
dc.subjectGLASen
dc.subjectIce sheetsen
dc.subjectGreenlanden
dc.subjectAntarcticaen
dc.subjectElevation changeen
dc.subjectVolume changeen
dc.subjectMass balanceen
dc.subjectGeodesyen
dc.subjectGlaciologyen
dc.subjectLaser altimetryen
dc.titleElevation and volume change of the ice sheets from GLAS : a comparison of methodsen
dc.typeThesisen
dc.date.updated2014-04-22T20:40:05Zen
dc.description.departmentAerospace Engineeringen
thesis.degree.departmentAerospace Engineeringen
thesis.degree.disciplineAerospace Engineeringen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelMastersen
thesis.degree.nameMaster of Science in Engineeringen


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