Inferring Modern Ice Mass Flux from Satellite Geodetic Constraints on Long Wavelength Gravity: Contending with a Suite of Confounding Geophysical Signals
Abstract
Satellite geodetic estimates of secular variations in low degree zonal harmonics of the Earth's geopotential (in particular, J2) have provided a key constraint on the integrated mass flux from polar ice sheets and glaciers since the mid 1970s. However, a major complication in analyzing these harmonics is the broad suite of additional geophysical processes that contribute to the secular trends, including, notably, the ongoing adjustment of the Earth from the ice age (glacial isostatic adjustment, GIA), groundwater depletion, water impoundment in artificial reservoirs and even, potentially, mantle convective flow. We report on a new budget analysis of these signals based on updated databases and advances in geophysical modeling of the GIA and mantle convection signals. In regards to GIA, inversions of large data sets related to the process have significantly refined models for the Earth's viscosity structure, while adjoint methods have significantly improved the accuracy of ongoing adjustment rates associated with the mantle convection process. We summarize each of these advances, and quantify the bias introduced in estimates of mass flux from polar ice sheets and glaciers by the neglect or inaccurate treatment of these additional, confounding signals.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMDI014..02G
- Keywords:
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- 3344 Paleoclimatology;
- ATMOSPHERIC PROCESSES;
- 0545 Modeling;
- COMPUTATIONAL GEOPHYSICS;
- 1038 Mantle processes;
- GEOCHEMISTRY;
- 8147 Planetary interiors;
- TECTONOPHYSICS