Closure of the budget of global sea level rise over the GRACE era: the importance and magnitudes of the required corrections for global glacial isostatic adjustment

摘要

The budget of global sea level rise includes contributions from several distinct factors, including thermosteric effects, the wasting of small ice sheets and glaciers, and the loss of mass by the great polar ice sheets and by the continents due to desiccation. Since the former contribution may be estimated on the basis of both hydrographic survey data and more recently using Argo float data, the second may be estimated on the basis of mass balance measurements on existing ice-fields, and the latter on the basis of modern GRACE-based time dependent gravity field measurements, the inputs to the globally averaged rate of sea level rise may be directly constrained. Since GRACE also provides a measurement of the rate at which mass is being added to the oceans, we are now in a position to ask whether this rate of mass addition to the oceans matches the rate at which mass is being removed from the continents. As demonstrated herein, the mass component of the budget of global sea level is closed within the observational errors. When the mass-derived contribution is added to the thermosteric contribution it is furthermore shown that the inference of the net rate of global sea level rise by the altimetric satellites Topex/Poseidon and Jason 1 is also reconcilable over the GRACE era. It is noted those individual terms in the budget, especially the contribution from small ice sheets and glaciers, remains insufficiently accurate. It is demonstrated that the lingering influence of the Late Quaternary ice-age upon sea level is profound and that closure of the budget requires an accurate model of its impact. (C) 2009 Elsevier Ltd. All rights reserved.