The crustal uplift determined at the Jakobshavn glacier (West Greenland) using ATM and GPS data

Ioana Stefania Muresan, Flavia Dalia Frumosu, Shfaqat Abbas Khan

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The Greenland ice sheet has experienced record melting in recent years. In order to estimate the ice loss we can make use of the earth’s natural elasticity to weigh the ice. Ice bends down the bedrock so when the ice melts away, the bedrock rises measurably in response. Throughout this abstract we present both a predicted and observed crustal upliftfor the Jakobshavn glacier using ATM data (Airborne Topographic Mapper) from NASA ATM flights during 1997, 2005 and 2010 supplemented with data provided from continuous Global Positioning System (GPS), measurements made on bedrock between 2005-2010.
In order to compute the crustal uplift in response to the ice mass loss of the Jakobshavnarea from the GPS stations, the convolution of the gridded thinning rates has been computed with the vertical-displacement Green’s function as described in [1].
Several manipulations of data were required in order to achieve a good prediction of thecrustal uplift. In this sense the programs Matlab and Geogrid-Gravsoft were used along withsome Fortran executable files. Furthermore, the GPS data which presents the difference in uplift is provided processed as a difference of data from the permanent GPS stations KAGA,ILUL and QEQE relative to the AASI station (Figure 1). Also, in order to compare the predicted uplift from ATM data with the observed uplift from GPS data the post-glacial rebound (PGR) rates have been subtracted.
The results obtained for the predictedcrustal uplift for KAAS is 11.62 mm/yr whilethe observed value was 16.321 mm/yr, forILAS 1.74 mm/yr and 1.53 mm/yr, for QEAS-0.189 mm/yr and 1.15 mm/yr. That being adifference of 4.701 mm/yr is found forKAAS, 0.21 mm/yr for ILAS and 1.339mm/yr for QEAS. The uncertaintiesassociated both with the ATM and GPSresults are 0.8 mm/yr for ATM and 0.5mm/yr for GPS. The total ice mass loss inkm3 of water predicted from the ATM dataconcerning the Jakobshavn area is -88.815between 2010 and 2005 and -83.599between 2005 and 1997.
It seems fair to state that this differences, between the predicted and observed rates, mayalso be due to the fact that not all the errors have been taken into account when computingthe observed results and also due to the fact that, perhaps, ice is melting in Greenland muchfaster than predicted.
Original languageEnglish
Publication date2012
Number of pages1
Publication statusPublished - 2012
EventGrøn dyst 2012 - Technical University of Denmark, Kgs. Lyngby, Denmark
Duration: 22 Jun 201222 Jun 2012


ConferenceGrøn dyst 2012
LocationTechnical University of Denmark
CityKgs. Lyngby

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