Using ground gravity to improve ice mass change estimation from GOCE gravity gradients in mid-west Greenland

Carl Christian Tscherning, Matija Herceg

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Vertical gravity gradient anomalies from the Gravity and steady-state Ocean Circulation Explorer (GOCE) DIR-3 model have been used to determine gravity anomalies in mid-west Greenland by using Least-Squares Collocation (LSC) and the Reduced Point Mass (RPM) method. The two methods give nearly identical results. However, compared to LSC, the RPM method needs less computational time as the number of equations to be solved in LSC equals the number of observations. The advantage of the LSC, however, is the acquired error estimates. The observation periods are winter 2009 and summer 2012. In order to enhance the accuracy of the calculated gravity anomalies, ground gravity data from West Greenland is used over locations where the gravity change resulting from ice mass changes is negligible, i.e. over solid rock. In the period considered, the gravity anomaly change due to changes in ice mass varies from −5 mGal to 4 mGal. It is negative over the outlet glacier Jacobshavn Isbræ, where the mass loss corresponds to a gravity change of approximately −4 mGal. When using only GOCE vertical gravity gradients, the error estimates range from 5 mGal at the coast to 17 mGal over the ice sheet. Introducing the ground gravity data from West Greenland in the prediction reduces the errors to range from 2 to 10 mGal.
Original languageEnglish
JournalStudia Geophysica et Geodaetica
Volume59
Number of pages13
ISSN0039-3169
DOIs
Publication statusE-pub ahead of print - 2015
Externally publishedYes

Keywords

  • GOCE gradients
  • Ice-mass
  • Least-Squares Collocation
  • Reduced Point Mass

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