摘要：GRACE and ICESat Antarctic mass-balance differences are resolved utilizing their dependencies on corrections for changes in mass and volume of the same underlying mantle material forced by ice-loading changes. Modeled gravimetry corrections are 5.22 times altimetry corrections over East Antarctica (EA) and 4.51 times over West Antarctica (WA), with inferred mantle densities 4.75 and 4.11 g cm −3 . Derived sensitivities ( S g , S a ) to bedrock motion enable calculation of motion ( δ B 0 ) needed to equalize GRACE and ICESat mass changes during 2003–08. For EA, δ B 0 is −2.2 mm a −1 subsidence with mass matching at 150 Gt a −1 , inland WA is −3.5 mm a −1 at 66 Gt a −1 , and coastal WA is only −0.35 mm a −1 at −95 Gt a −1 . WA subsidence is attributed to low mantle viscosity with faster responses to post-LGM deglaciation and to ice growth during Holocene grounding-line readvance. EA subsidence is attributed to Holocene dynamic thickening. With Antarctic Peninsula loss of −26 Gt a −1 , the Antarctic total gain is 95 ± 25 Gt a −1 during 2003–08, compared to 144 ± 61 Gt a −1 from ERS1/2 during 1992–2001. Beginning in 2009, large increases in coastal WA dynamic losses overcame long-term EA and inland WA gains bringing Antarctica close to balance at −12 ± 64 Gt a −1 by 2012–16.
