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Abstract:
Started in 2002, the GRACE “Gravity Recovery and Climate Experiment” gravity mission has allowed mapping the changes in the Earth’s gravitational field over about 15 years (2002-2017). We introduce a method to compute the ice mass-balance from GRACE gravity variations, which is particularly suited to suppress the leakage contribution to the field. The method, called ECS (Extremely Compact Source) yields an ECS model, where the sources are very efficiently separated. It thus allows the user to compute the associated mass and gravity field of each source and to remove unwanted effects, such as those related to the leakage. We apply the method to estimate the mass changes of the main Icelandic glaciers, in the period 2002-2017. The leakage effect is particularly evident in the Vatnajökull ice cap area, due to its proximity to the strong gravity field related to the Greenland ice sheet melting. We show that ECS eliminates the need for independent data sets (e.g., ICEsat or Envisat) and the use of a-priori information for proper separation of different contributions.
