Modeling Viscoelastic Solid Earth Deformation Due To Ice Age and Contemporary Glacial Mass Changes in ASPECT

The redistribution of past and present ice and ocean loading on Earth's surface causes solid Earth deformation and geoid changes, known as glacial isostatic adjustment. The deformation is controlled by elastic and viscous material parameters, which are inhomogeneous in the Earth. We present a new viscoelastic solid Earth deformation model in...

Identifying Geographical Patterns of Transient Deformation in the Geological Sea Level Record

In this study, we examine the effect of transient mantle creep on the prediction of glacial isostatic adjustment (GIA) signals. Specifically, we compare predictions of relative sea level (RSL) change from GIA from a set of Earth models in which transient creep parameters are varied in a simple Burgers model to a reference case with a Maxwell...

The Impact of a 3-D Earth Structure on Glacial Isostatic Adjustment in Southeast Alaska Following the Little Ice Age

In Southeast Alaska, extreme uplift rates are primarily caused by glacial isostatic adjustment (GIA), as a result of ice thickness changes from the Little Ice Age to the present combined with a low-viscosity asthenosphere. Previous GIA models adopted a 1-D Earth structure. However, the actual Earth structure is likely more complex due to the...

Long‐Wavelength Gravity Field Constraint on the Lower Mantle Viscosity in North America

The long‐wavelength negative gravity anomaly over Hudson Bay coincides with the area depressed by the Laurentide Ice Sheet during the Last Glacial Maximum, suggesting that it is, at least partly, caused by glacial isostatic adjustment (GIA). Additional contributions to the static gravity field stem from surface dynamic topography, core‐mantle...

Uncertainty Estimation in Regional Models of Long-Term GIA Uplift and Sea Level Change: An Overview

This work provides a comparison of four approaches that can be used to describe uncertainty in models of the long-term glacial isostatic adjustment (GIA) process. The four methods range from pessimistic to optimistic representations of GIA uncertainty. Each estimation method is applied to selected one dimensional GIA model predictions and...

Modeling Satellite Gravity Gradient Data to Derive Density, Temperature, and Viscosity Structure of the Antarctic Lithosphere

In this study we combine seismological and petrological models with satellite gravity gradient data to obtain the thermal and compositional structure of the Antarctic lithosphere. Our results indicate that Antarctica is largely in isostatic equilibrium, although notable anomalies exist. A new Antarctic Moho depth map is derived that fits the...

Reversal of the Direction of Horizontal Velocities Induced by GIA as a Function of Mantle Viscosity

In regions undergoing glacial isostatic adjustment present-day horizontal surface motion is observed to point mostly, but not always, away from the former ice load. To interpret these observations, we investigate the direction of horizontal velocities using glacial isostatic adjustment models. The direction is controlled by the opposing...

Estimating geocenter motion and changes in the Earth’s dynamic oblateness from GRACE and geophysical models

Geocenter motion and changes in the Earth’s dynamic oblateness (J2) are of great importance in many applications. Among others, they are critical indicators of largescale mass redistributions, which is invaluable to understand ongoing global climate change. The revolutionary Gravity Recovery and Climate Experiment (GRACE) satellite mission...

Gravity Field Constraints on the Upper Mantle of Northwestern Europe

In the last decade, the gravity field of the Earth has been observed with increased coverage due to dedicated satellite missions, which resulted in higher resolution and more accurate global gravity field models than were previously available. These models make it possible to study large scale processes such as solid Earth deformation after...

A data-driven model for constraint of present-day glacial isostatic adjustment in North America

Geodetic measurements of vertical land motion and gravity change are incorporated into an a priori model of present-day glacial isostatic adjustment (GIA) in North America via least-squares adjustment. The result is an updated GIA model wherein the final predicted signal is informed by both observational data, and prior knowledge (or...

Observed changes in the Earth’s dynamic oblateness from GRACE data and geophysical models

A new methodology is proposed to estimate changes in the Earth’s dynamic oblateness (?J2 or equivalently, ?5??C20) on a monthly basis. The algorithm uses monthly Gravity Recovery and Climate Experiment (GRACE) gravity solutions, an ocean bottom pressure model and a glacial isostatic adjustment (GIA) model. The resulting time series agree...

Widespread low rates of Antarctic glacial isostatic adjustment revealed by GPS observations

Bedrock uplift in Antarctica is dominated by a combination of glacial isostatic adjustment (GIA) and elastic response to contemporary mass change. Here, we present spatially extensive GPS observations of Antarctic bedrock uplift, using 52% more stations than previous studies, giving enhanced coverage, and with improved precision. We observe...

Improved constraints on models of glacial isostatic adjustment: A review of the contribution of ground-based geodetic observations

The provision of accurate models of Glacial Isostatic Adjustment (GIA) is presently a priority need in climate studies, largely due to the potential of the Gravity Recovery and Climate Experiment (GRACE) data to be used to determine accurate and continent-wide assessments of ice mass change and hydrology. However, modelled GIA is uncertain due...

A comparison of coincident GRACE and ICESat data over Antarctica

In this study, we present a comparison of coincident GRACE and ICESat data over Antarctica. The analysis focused on the secular changes over a 4-year period spanning from 2003 to 2007, using the recently reprocessed and publicly available data sets for both missions. The results show that the two independent data sets possess strong spatial...

Shallow-earth rheology from glacial isostasy and satellite gravity: A sensitivity analysis for GOCE

In recent years, satellite gravity missions have been launched that probe the earth's long- to mediumwavelength (1000 - 500 km) gravity field. The upcoming ESA satellite gravity mission GOCE is predicted to measure the gravity field with an accuracy of a few centimeters at spatial scales of 100 km. Such a high-resolution gravity field contains...