A GPS velocity field for Fennoscandia and a consistent comparison to glacial isostatic adjustment models

Abstract

Our GPS velocity field is directly realized in a GIA reference frame. Using this method (named the GIA frame approach) we are able to constrain GIA models with minimal influence of errors in the reference frame or biasing signals from plate tectonics. The drawbacks are more degrees of freedom that might mask real but unmodeled signals. Monte Carlo tests suggest that our approach is robust at the 97% level in terms of correctly separating different models of ice history but, depending on deformation patterns, the identified Earth model may be slightly biased in up to 39% of cases. We compare our results to different one-and three-dimensional GIA models employing different global ice-load histories. The GIA models generally provide good fit to the data but there are still significant discrepancies in some areas. We suggest that these differences are mainly related to inaccuracies in the ice models and/or lateral inhomogeneities in the Earth structure under Fennoscandia. Thus, GIA models still need to be improved, but the GIA frame approach provides a base for further improvements.

Glacial Isostatic Adjustment modelling: historical perspectives, recent advances, and future directions

“…In areas where non-GIA signals are well constrained and there is a dense network of measurements, such as across North America (Sella et al, 2007) or Fennoscandia (Lidberg et al, 2007), GPS data have successfully been used to calibrate GIA models (e.g. Milne et al, 2001;Milne et al, 2004;Lidberg et al, 2010;Kierulf et al, 2014;Peltier et al, 2015). However, in regions where contemporary ice mass change also contributes to present-day solid Earth deformation, it becomes difficult to disentangle contributions from past and present ice-sheet change 395…”

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

“…The most recent model in this series, ICE-6G_C (VM5a), uses the largest set of space geodetic constraints currently available to both constrain and validate the reconstruction (Argus et al, 2014;Kierulf et al, 2014;Peltier et 41 al., 2015). Except for the glaciologically-derived Greenland component (Tarasov and Peltier, 2002) of ICE-5/6G, these models are not subject to any explicit glaciological constraints.…”

“…Likewise, the recent expansion of coverage of measurements of present-day vertical velocities from continuous or repeat GPS (e.g. Kierulf et al, 2014) has significantly improved constraint data for GIA-based ice sheet reconstructions (Argus et al, 2014;Peltier et al, 2015).…”

Projected 21st Century Sea-Level Changes, Observed Sea Level Extremes, and Sea Level Allowances for Norway

“…The coastline is largely characterized by steep topography and exposed bedrock that is resistant to erosion. In addition to this, the land surface is experiencing on-going uplift due to the loss of the large ice sheet that once covered Fennoscandia (a process known as glacial isostatic adjustment, GIA; e.g., [1,2]). It is well recognized that this uplift process will act to mitigate future sea-level rise (e.g., [3]).…”