Analysis of Multi-decadal Fennoscandian Geodetic Data Sets in an Environment of Present-Day Mass Loss: Implications for Earth Structure and Sea-level Change

DESCRIPTION: The BIFROST (Baseline Inferences For Rebound Observations, Sea level, and Tectonics) GNSS network in Fennoscandia has been in operation since the mid-to-late 1990s, providing time series that are two decades in length at least. There have been significant advances in the ability numerically to calculate Glacial Isostatic Adjustment (GIA) fields based on more complex Earth models, and there have been continuing advances in constraining and modeling the Late Pleistocene ice history. There is a greater scientific appreciation for the complexities of present-day sea-level change (for example, the importance of self-gravity of ice sheets and the associated sea-level fingerprint). GRACE now provides a means for monitoring mass load changes in Earth's ice sheets to great accuracy. New methods for the combination of data and models have emerged. All these important changes lead us to conclude that a new study based on the BIFROST data has great potential to lead to significantly improved GIA fields and uncertainties for Fennoscandia, a better understanding of the constraints on mantle viscosity that can be inferred from these fields, and a consistent model for sea-level change in the region.

Using the standard one-dimensional (i.e., radially varying) Earth modeling approach for GIA as a starting point, we will first investigate the impact on Earth-model inferences from geodetic data of deformation and sea-level change associated with ongoing global surface mass change. We will also derive new data-driven GIA fields (3-D deformation, gravity, and sea level) using extensions to our Bayesian approach for determining data-driven GIA fields [e.g., Hill et al., 2010]. We will investigate the impact within Fennoscandia of 3-D Earth models that include horizontal variations in viscosity and lithospheric strength, and address the question of whether these signals can be detected using this highly accurate data set (and, if not, why not). We will produce a consistent sea-level model for Fennoscandia that includes effects from non-linear mass changes in Earth's ice sheets, as measured by GRACE.