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Abstract:
Ongoing mass changes in the Antarctic ice sheet have been observed as gravity changes by the Gravity Recovery and Climate Experiment (GRACE) satellites. The gravity signal also includes the component of the solid Earth’s response to surface mass change (Glacial Isostatic Adjustment, GIA). Therefore, estimates of the ice mass change from GRACE data require subtraction of the gravity rates predicted by the GIA model (GIA correction). Previous studies imply that the long-wavelength components dominate the Antarctic GIA correction. To further understand the long-wavelength contributions, we compute the degree amplitude of Antarctic GIA correction in the spherical harmonic expansion. The degree dependence of Antarctic GIA correction is examined here using some typical ice history models. The Antarctic GIA corrections converge by degrees ~ 30 regardless of the choice of ice history models. When the GIA model includes Northern Hemisphere ice history, the degree amplitudes for degrees < 10 vary significantly at each degree. The degree-2 GIA component, due to the influence of the Northern Hemisphere ice history, accounts for 30% or more of the total Antarctic GIA correction. It will be necessary to pay attention to the treatment of the degree-2 component.
