Constraining glacier elevation and mass changes in South America

Braun, Matthias; Malz, Philipp; Sommer, Christian; Farías-Barahona, David; Sauter, Tobias; Casassa, Gino; Soruco, Álvaro; Skvarca, Pedro; Seehaus, Thorsten

doi:10.1038/s41558-018-0375-7

Cited by 187 publications

(271 citation statements)

References 44 publications

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“…Our assessment indicates that these simplified approaches, which do not take into account ice velocity, have limited value to reveal the precise details of the bed topography beneath the icefields. To extend our results to lower elevation, we recommend using a mass conservation method combining ice flow vectors (Mouginot & Rignot, 2015), surface mass balance models (Lenaerts et al, 2014;Schaefer et al, 2015), and changes in surface elevation (Braun et al, 2019) as done successfully for ice sheets (Morlighem et al, 2014), mountain glaciers and ice fields (Rabatel et al, 2018).…”

Section: 1029/2019gl082485mentioning

confidence: 99%

Ice Thickness and Bed Elevation of the Northern and Southern Patagonian Icefields

Millan

Rignot

Rivera

et al. 2019

Geophysical Research Letters

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The Northern and Southern Patagonian Icefields are the largest ice masses in the Southern Hemisphere outside Antarctica, but their ice volume and bed topography are poorly known. Here, we combine airborne gravity data collected in 2012 and 2016, with radar data from the Warm Ice Experiment Sounder and Centro de Estudios Científicos's to map bed elevation and ice thickness in great detail. We perform a 3‐D inversion of the gravity data constrained by radar‐derived thickness and fjord bathymetry to infer bed elevation at 500‐m spacing, with a precision of about 60 m. We detect deep glacial valleys with ice thickness exceeding 1,400 m and sectors below sea level on the western branch of Glaciar Pio XI, Occidental, between San Rafael and Colonia, and near Fitz Roy. We calculate an ice volume of 4,756 ± 923 km3 for Northern Patagonia Icefield and Southern Patagonia Icefield, or 40 times the volume of glaciers in the European Alps.

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Section: 1029/2019gl082485mentioning

confidence: 99%

Ice Thickness and Bed Elevation of the Northern and Southern Patagonian Icefields

Millan

Rignot

Rivera

et al. 2019

Geophysical Research Letters

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“…In the following, we illustrate, using our data, how the results could be corrected to account for the radar penetration in cases where the observation period is shorter and hence the penetration has a significant effect on the results. We can estimate signal penetration similar to previous studies (e.g., Malz et al, 2018;Braun et al, 2019): The radar penetration takes place only in the accumulation area (assumed AAR of 50%) and is between 0 m (at ELA) to 5 m at the summit. On average (over the elevation range of the accumulation zone), this makes 2.5 m with an uncertainty of 2.5 m. Averaged over the entire glacier, then, this is halved again to 1.25 ± 1.25 m (because only the accumulation area, which covers about half of the glacier, will be affected by radar penetration).…”

Section: Uncertainties and Biasmentioning

confidence: 67%

Elevation Changes of West-Central Greenland Glaciers From 1985 to 2012 From Remote Sensing

2020

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Greenlandic glaciers distinct from the ice sheet make up 12% of the global glacierized area and store about 10% of the global glacier ice volume (Farinotti et al., 2019). However, knowledge about recent climate change-induced volume changes of these 19,000 individual glaciers is limited. The small number of available glaciological and geodetic mass-balance observations have a limited spatial coverage, and the representativeness of these measurements for the region is largely unknown, factors which make a regional assessment of mass balance challenging. Here we use two recently released digital elevation models (DEMs) to assess glacier-wide elevation changes of 1,526 glaciers covering 3,785 km 2 in west-central Greenland: The historical AeroDEM representing the surface in 1985 and a TanDEM-X composite representing 2010-2014. The results show that on average glacier surfaces lowered by about 14.0 ± 4.6 m from 1985 until 2012 or 0.5 ± 0.2 m yr −1 , which is equivalent to a sample mass loss of ∼45.1 ± 14.9 Gt in total or 1.7 ± 0.6 Gt yr −1 . Challenges arise from the nature of the DEMs, such as large areas of data voids, fuzzy acquisition dates, and potential radar penetration. We compared several different interpolation methods to assess the best method to fill data voids and constrain unknown survey dates and the associated uncertainties with each method. The potential radar penetration is considered negligible for this assessment in view of the overall glacier changes, the length of the observation period, and the overall uncertainties. A comparison with earlier studies indicates that for glacier change assessments based on ICESat, data selection and averaging methodology strongly influences the results from these spatially limited measurements. This study promotes improved assessments of the contribution of glaciers to sea-level rise and encourages to extend geodetic glacier mass balances to all glaciers on Greenland.

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“…To obtain the TDX DEM we use the SRTM DEM void-filled LP DAAC NASA Version 3 with 1 arcsec ground resolution (30 m). We process TDX DEM and calculate glacier elevation changes following the workflow by Braun et al (2019), which consists of: (1) Selection of the TDX scenes from the same season (Feb-Apr 2013) as the SRTM mission, in order to minimise the effects of radar penetration into snow and firn (table S1 is available online at stacks.iop.org/ERL/15/034036/ mmedia).…”

Section: Tandem-x and Srtmmentioning

confidence: 99%

“…The void-filled SRTM DEM is used as a height reference for the elevation bins. Details of the processing and calculation of TDX DEM are presented in Seehaus et al (2015), Braun et al (2019), and Farías-Barahona et al (2019).…”

Section: Tandem-x and Srtmmentioning

confidence: 99%

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Detailed quantification of glacier elevation and mass changes in South Georgia

Farías-Barahona

Sommer

Sauter

et al. 2020

Environ. Res. Lett.

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Most glaciers in South America and on the Antarctic Peninsula are retreating and thinning. They are considered strong contributors to global sea level rise. However, there is a lack of glacier mass balance studies in other areas of the Southern Hemisphere, such as the surrounding Antarctic Islands. Here, we present a detailed quantification of the 21st century glacier elevation and mass changes for the entire South Georgia Island using bi-static synthetic aperture radar interferometry between 2000 and 2013. The results suggest a significant mass loss since the beginning of the present century. We calculate an average glacier mass balance of −1.04±0.09 m w.e.a −1 and a mass loss rate of 2.28±0.19 Gt a −1 (2000-2013), contributing 0.006±0.001 mm a −1 to sea-level rise. Additionally, we calculate a subaqueous mass loss of 0.77±0.04 Gt a −1 (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016), with an area change at the marine and lake-terminating glacier fronts of −6.58±0.33 km 2 a −1 , corresponding to ∼4% of the total glacier area. Overall, we observe negative mass balance rates in South Georgia, with the highest thinning and retreat rates at the large outlet glaciers located at the north-east coast. Although the spaceborne remote sensing dataset analysed in this research is a key contribution to better understanding of the glacier changes in South Georgia, more detailed field measurements, glacier dynamics studies or further long-term analysis with high-resolution regional climate models are required to precisely identify the forcing factors.

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Constraining glacier elevation and mass changes in South America

Cited by 187 publications

References 44 publications

Ice Thickness and Bed Elevation of the Northern and Southern Patagonian Icefields

Ice Thickness and Bed Elevation of the Northern and Southern Patagonian Icefields

Elevation Changes of West-Central Greenland Glaciers From 1985 to 2012 From Remote Sensing

Detailed quantification of glacier elevation and mass changes in South Georgia

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