01-05-17 | Sea level: Use and comparisons of static equilibrium models with data


Dr. Mark Tamisiea
Center for Space Research

Time and Place

January 5, 2017 – Thursday – 2:00 PM
WPR Building, Conference Room 2.806
3925 W. Braker Lane, Suite 200, Austin, Texas 78759

Regional variations in sea level can be caused by crustal deformation and gravitational perturbations due to past and present-day changes in continental mass loads, whether associated with ice sheets, glaciers, or hydrological water storage. These static equilibrium (i.e. ignoring dynamical oceanographic effects) sea-level changes are associated with the redistribution of mass. In this regard, data collected by the Gravity Recovery and Climate Experiment (GRACE) satellites are essential, as they provide us with the first global view of regional mass variations. While GRACE data are vital, other geodetic observations are also necessary to identify the causes of sea-level change.

Modern geodetic systems allow us to observe sea level change with unprecedented spatial and temporal detail. However, tide gauges, altimetry, and gravity measurements each observe a different aspect of the Earth system’s response. Indeed, glacial isostatic adjustment (GIA) and present-day load changes introduce systematic differences between the observation systems. Inferences drawn from these data types can easily be misinterpreted without an appreciation of these large-scale mechanisms. In this talk, I discuss the use of GIA and present-day ice loss models in sea-level analysis. GIA models introduce large, uncertain corrections into the GRACE analysis, and I will suggest the use of drift-free ocean bottom pressure measurements as a possible check. In addition, the best method for handling rotational feedback, a notable far-field feature in both types of models, remains an open question.

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