Crustal deformation across the Southern Patagonian Icefield observed by GNSS

Richter, Andreas; Ivins, E. R.; Lange, Heiner; Mendoza, Luciano Pedro Oscar; Schröder, Ludwig; Hormaechea, José Luis; Casassa, Gino; Marderwald, Eric; Fritsche, Mathias; Perdomo, R.; Horwath, Martin; Dietrich, Reinhard

doi:10.1016/j.epsl.2016.07.042

Cited by 56 publications

(73 citation statements)

References 42 publications

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“…This fact creates a bias that retrieves structure more appropriate to cratonic mantle, where most of the signal is generated and measured (Caron et al, ; Nordman et al, ). This is problematic when regional viscosity is significantly different, and there has been robust Neoglacial or Little Ice Age mass transfer (e.g., Richter et al, ). For example, near the coast of Marie Byrd Land where the upper mantle viscosity is thought to be very low, possibly near 10 18 Pa s, our ensemble predicts 1.96 ± 0.65, 1.33 ± 0.49, and 1.64 ± 0.60 mm/yr of uplift, while the observed values are 12.1 ± 2.22, 22.6 ± 2.71, and 37.0 ± 5.5 mm/yr, respectively.…”

Section: Resultsmentioning

confidence: 99%

GIA Model Statistics for GRACE Hydrology, Cryosphere, and Ocean Science

Caron

Ivins

Larour

et al. 2018

Geophysical Research Letters

200

366

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We provide a new analysis of glacial isostatic adjustment (GIA) with the goal of assembling the model uncertainty statistics required for rigorously extracting trends in surface mass from the Gravity Recovery and Climate Experiment (GRACE) mission. Such statistics are essential for deciphering sea level, ocean mass, and hydrological changes because the latter signals can be relatively small (≤2 mm/yr water height equivalent) over very large regions, such as major ocean basins and watersheds. With abundant new >7 year continuous measurements of vertical land motion (VLM) reported by Global Positioning System stations on bedrock and new relative sea level records, our new statistical evaluation of GIA uncertainties incorporates Bayesian methodologies. A unique aspect of the method is that both the ice history and 1‐D Earth structure vary through a total of 128,000 forward models. We find that best fit models poorly capture the statistical inferences needed to correctly invert for lower mantle viscosity and that GIA uncertainty exceeds the uncertainty ascribed to trends from 14 years of GRACE data in polar regions.

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Section: Resultsmentioning

confidence: 99%

GIA Model Statistics for GRACE Hydrology, Cryosphere, and Ocean Science

Caron

Ivins

Larour

et al. 2018

Geophysical Research Letters

200

366

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“…Viscosities lower than 10 19 Pa s are also inferred for West Antarctica (van der Wal et al, ). Lange et al () estimated a range of 1.6–8 × 10 18 Pa s for the asthenospheric viscosity beneath southern Patagonia, and Richter et al () presented an expanded data set that supports the low end of that range. Postseismic deformation studies for a variety of earthquakes commonly find viscosity estimates in the range of 10 18 –10 19 Pa s. Klemann et al () assumed an asthenospheric viscosity of 10 19 Pa s for Patagonia, with a viscosity one order of magnitude lower for the mantle wedge.…”

Section: Discussionmentioning

confidence: 96%

Geodetic Observations of Time‐Variable Glacial Isostatic Adjustment in Southeast Alaska and Its Implications for Earth Rheology

Freymueller

2019

JGR Solid Earth

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Global Positioning System observations in Southeast Alaska show evidence for interannual variations in uplift rates, which are consistent with an acceleration of mass loss rates across the region from the 1990s to 2012. We constructed an updated regional loading model based on updated twentieth century average deglaciation estimates. This model features a larger mass loss rate overall than the model used in previous studies. We adopted a viscosity model with an upper and lower mantle viscosity from VM5a but with a low viscosity asthenosphere as in previous regional studies. We varied the asthenospheric thickness, asthenospheric viscosity, and lithospheric thickness to find the Earth model that best fits the data, which has a lithospheric thickness of 55 km and an asthenosphere with thickness 230 km and viscosity 3 × 1019 Pa s. There is a strong tradeoff between the asthenosphere thickness and viscosity, and different estimates or assumptions about the asthenospheric thickness is one of the main causes of the varying viscosity estimates of previous studies. We find a higher viscosity than previous studies in part because we find that a thicker asthenosphere fits the data better than a thinner one and also because the higher twentieth century mass loss rate compared to earlier studies requires a higher viscosity to predict the same uplift rates. Vertical velocities predicted by the model drop rapidly with distance from the ice masses, while horizontal velocities are smaller but extend for a longer distance.

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“…Those measurements are additionally influenced by uncertainties in the estimation of the glacio-isostatic uplift (GIA) for which rates are known to be one of the highest in Patagonia in a global comparison. Recent studies report maximum uplift rates of up to 41 mm·a −1 at the margin of the icefield [15,16,42]. Moreover, the GRACE measurements cover both icefield plus ice bodies to the north and south of the NPI and SPI.…”

Section: Elevation and Mass Changes Of The Entire Spimentioning

confidence: 99%

“…However, the measured gravity signal is also strongly influenced by the mass changes due to glacio-isostatic adjustments. For Patagonia, rates of up to 41 mm·a −1 have been reported close to the SPI [15,16]. Moreover, the integrated GRACE signal cannot resolve individual glacier catchments.…”

Section: Introductionmentioning

confidence: 99%

Elevation and Mass Changes of the Southern Patagonia Icefield Derived from TanDEM-X and SRTM Data

et al. 2018

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Abstract:The contribution to sea level rise from Patagonian icefields is one of the largest mass losses outside the large ice sheets of Antarctica and Greenland. However, only a few studies have provided large-scale assessments in a spatially detailed way to address the reaction of individual glaciers in Patagonia and hence to better understand and explain the underlying processes. In this work, we use repeat radar interferometric measurements of the German TerraSAR-X-Add-on for Digital Elevation Measurements (TanDEM-X) satellite constellation between 2011/12 and 2016 together with the digital elevation model from the Shuttle Radar Topography Mission (SRTM) in 2000 in order to derive surface elevation and mass changes of the Southern Patagonia Icefield (SPI). Our results reveal a mass loss rate of −11.84 ± 3.3 Gt·a −1 (corresponding to 0.033 ± 0.009 mm·a −1 sea level rise) for an area of 12573 km 2 in the period 2000-2015/16. This equals a specific glacier mass balance of −0.941 ± 0.19 m w.e.·a −1 for the whole SPI. These values are comparable with previous estimates since the 1970s, but a magnitude larger than mass change rates reported since the Little Ice Age. The spatial pattern reveals that not all glaciers respond similarly to changes and that various factors need to be considered in order to explain the observed changes. Our multi-temporal coverage of the southern part of the SPI (south of 50.3 • S) shows that the mean elevation change rates do not vary significantly over time below the equilibrium line. However, we see indications for more positive mass balances due to possible precipitation increase in 2014 and 2015. We conclude that bi-static radar interferometry is a suitable tool to accurately measure glacier volume and mass changes in frequently cloudy regions. We recommend regular repeat TanDEM-X acquisitions to be scheduled for the maximum summer melt extent in order to minimize the effects of radar signal penetration and to increase product quality.

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Crustal deformation across the Southern Patagonian Icefield observed by GNSS

Cited by 56 publications

References 42 publications

GIA Model Statistics for GRACE Hydrology, Cryosphere, and Ocean Science

GIA Model Statistics for GRACE Hydrology, Cryosphere, and Ocean Science

Geodetic Observations of Time‐Variable Glacial Isostatic Adjustment in Southeast Alaska and Its Implications for Earth Rheology

Elevation and Mass Changes of the Southern Patagonia Icefield Derived from TanDEM-X and SRTM Data

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