Re-estimation of glacier mass loss in Greenland from GRACE with correction of land-ocean leakage effects

Abstract The Gravity Recovery and Climate Experiment (GRACE) satellites can estimate the high-precision time-varying gravity field and the changes of Earth's surface mass, which have been widely used in water cycle and glacier mass balance. However, one of larger errors in GRACE measurements, land–ocean leakage effects, restricts high precision retrieval of ocean mass and terrestrial water storage variations along the coasts, particularly estimation of mass loss in Greenland. The land–ocean leakage effect along the coasts in Greenland will contaminate the mass loss signals with significant signal attenuation. In this paper, the precise glacier mass loss in Greenland from GRACE is re-estimated with correction of land–ocean leakage effects using the forward gravity modeling. The loss of Greenland ice-sheets is − 102.8 ± 9.01 Gt/a without removing leakage effect, but − 183.0 ± 19.91 Gt/a after removing the leakage effect from September 2003 to March 2008, which has a good agreement with ICESat results of − 184.8 ± 28.2 Gt/a. From January 2003 to December 2013, the total Greenland ice-sheet loss is at − 261.54 ± 6.12 Gt/a from GRACE measurements with removing the leakage effect by 42.4%, while two-thirds of total glacier melting in Greenland occurred in southern Greenland in the past 11 years. The secular leakage effects on glacier melting estimate is mainly located in the coastal areas, where larger glacier signals are significantly attenuated due to leaking out into the ocean. Furthermore, the leakage signals also have remarkable effects on seasonal and acceleration variations of glacier mass loss in Greenland. More significantly accelerated loss of glacier mass in Greenland is found at − 26.19 Gt/a2 after correcting for leakage effects.

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