Reanalysis of long-term series of glaciological and geodetic mass balance  for 10 Norwegian glaciers

Andreassen, Liss M.; Elvehøy, Hallgeir; Kjøllmoen, Bjarne; Engeset, Rune

doi:10.5194/tc-10-535-2016

Cited by 75 publications

(129 citation statements)

References 38 publications

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“…are available (Andreassen et al, 2016). The discrepancy between new and old outlines are minor and do not influence the results presented in this paper.…”

Section: Additional Datamentioning

confidence: 72%

Using SAR satellite data time-series for regional glacier mapping

Winsvold¹,

Kääb²,

Nuth³

et al. 2017

Preprint

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With dense SAR satellite data time-series it is possible to map surface and subsurface glacier properties that vary in time. On 10 Sentinel-1A and Radarsat-2 backscatter images over mainland Norway and Svalbard, we have used descriptive methods for outlining the possibilities of using SAR time-series for mapping glaciers. We present five application scenarios, where the first shows potential for tracking transient snow lines with SAR backscatter time-series, and correlates with both optical satellite images (Sentinel-2A and Landsat 8) and equilibrium line altitudes derived from in situ surface mass balance data. In the second application scenario, time-series representation of glacier facies corresponding to SAR glacier zones shows 15 potential for a more accurate delineation of the zones and how they change in time. The third application scenario investigates the firn evolution using dense SAR backscatter time-series together with a coupled energy balance and multilayer firn model. We find strong correlation between backscatter signals with both the modeled firn air-content and modeled wetness in the firn. In the fourth application scenario, we highlight how winter rain events can be detected in SAR timeseries, revealing important information about the area extent of internal accumulation. Finally, in the last application 20 scenario, averaged summer SAR images were found to have potential in assisting the process of mapping glaciers outlines, especially in the presence of seasonal snow. Altogether we present examples of how to map glaciers and to further understand glaciological processes using the existing and future massive amount of multi-sensor time-series data. Our results reveal the potential of satellite imagery for automatically derived products as important input in modeling assessments and glacier change analysis. 25

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“…are available (Andreassen et al, 2016). The discrepancy between new and old outlines are minor and do not influence the results presented in this paper.…”

Section: Additional Datamentioning

confidence: 72%

Using SAR satellite data time-series for regional glacier mapping

Winsvold¹,

Kääb²,

Nuth³

et al. 2017

Preprint

Self Cite

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“…In addition and according to Andreassen et al (2016), we assume that the extrapolation over areas not covered by point 150 measurements inherits uncertainties of ±0.10 m w.e. a -1 .…”

Section: The Glaciological Methodsmentioning

confidence: 99%

A reanalysis of one decade of the mass balance series on Hintereisferner, Ötztal Alps, Austria: a detailed view into annual geodetic and glaciological observations

Klug

Bollmann

Galos

et al. 2017

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Abstract. This study presents a reanalysis of the glaciologically obtained 2001-11 annual glacier mass balances record at Hintereisferner, Ötztal Alps, Austria. The reanalysis is accomplished through a comparison with geodetically derived mass 15 changes, using annual high-resolution airborne laser scanning (ALS). The grid based adjustments for the method-inherent differences are discussed along with associated uncertainties and discrepancies of the two forms of mass balance measurements. A statistical comparison of the two datasets shows no significant difference for seven annual as well as the cumulative mass changes over the ten years record. Yet, the statistical view hides significant differences in the mass balance The validity of the results is critically assessed and concludes that exceptional atmospheric circumstances can render the usual glaciological observational network inadequate. Furthermore, we consider that ALS data reliably reproduce the annual mass balance and can be seen as calibration tools of or, under certain circumstances, even as a substitute for the glaciological method.

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“…Several studies have shown that basal and internal melt can be important contributors to total glacier ablation, depending on the specific glacier and the climatic setting (e.g., Alexander et al, 2011;Oerlemans, 2013;Andreassen et al, 2016). Generally, the most important sources of energy for subsurface melt on temperate glaciers are related to the conversion of potential energy by water runoff inside and at the base of the glacier.…”

Section: The Role Of Basal and Internal Meltmentioning

confidence: 99%

“…For this reason we clearly flag all results related to modeling and provide full methodical transparency in order to enable possible data users to decide whether the data suit their purpose or not. The applied model was run in its point configuration as the purpose of this study is not to use a model for the spatial extrapolation of point measurements on the glacier-wide scale as done in a number of other studies Barandun et al, 2015;Kronenberg et al, 2016;Sold et al, 2016) but is rather to reproduce a best possible estimate of annual balance values for point locations where ablation stakes were placed in the subsequent years. In this configuration, the model performance can be validated directly using data from available stake measurements.…”

Section: Point Mass Balance Modelingmentioning

confidence: 99%

“…Mass balance models have been used to extrapolate point measurements to the glacier scale (e.g., Huss et al, , 2013Sold et al, 2016), to homogenize annual or seasonal mass balance with respect to the fixed date method or to investigate the impact of changing glacier area and hypsometry on values of mean specific mass balance (Paul, 2010;Huss et al, 2012). Extensive accumulation measurements (e.g., Sold et al, 2016) provide detailed information on the intractable problem of spatial variability of snow accumulation while additional optical imagery gives information on the evolving snow cover (e.g., Huss et al, 2013;Barandun et al, 2015;Kronenberg et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Reanalysis of a 10-year record (2004–2013) of seasonal mass balances at Langenferner/Vedretta Lunga, Ortler Alps, Italy

et al. 2017

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Abstract. Records of glacier mass balance represent important data in climate science and their uncertainties affect calculations of sea level rise and other societally relevant environmental projections. In order to reduce and quantify uncertainties in mass balance series obtained by direct glaciological measurements, we present a detailed reanalysis workflow which was applied to the 10-year record (2004 to 2013) of seasonal mass balance of Langenferner, a small glacier in the European Eastern Alps. The approach involves a methodological homogenization of available point values and the creation of pseudo-observations of point mass balance for years and locations without measurements by the application of a process-based model constrained by snow line observations. We examine the uncertainties related to the extrapolation of point data using a variety of methods and consequently present a more rigorous uncertainty assessment than is usually reported in the literature.Results reveal that the reanalyzed balance record considerably differs from the original one mainly for the first half of the observation period. For annual balances these misfits reach the order of > 300 kg m −2 and could primarily be attributed to a lack of measurements in the upper glacier part and to the use of outdated glacier outlines. For winter balances respective differences are smaller (up to 233 kg m −2 ) and they originate primarily from methodological inhomogeneities in the original series. Remaining random uncertainties in the reanalyzed series are mainly determined by the extrapolation of point data to the glacier scale and are on the order of ±79 kg m −2 for annual and ±52 kg m −2 for winter balances with values for single years/seasons reaching ±136 kg m −2 . A comparison of the glaciological results to those obtained by the geodetic method for the period 2005 to 2013 based on airborne laser-scanning data reveals that no significant bias of the reanalyzed record is detectable.

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Reanalysis of long-term series of glaciological and geodetic mass balance for 10 Norwegian glaciers

Cited by 75 publications

References 38 publications

Using SAR satellite data time-series for regional glacier mapping

Using SAR satellite data time-series for regional glacier mapping

A reanalysis of one decade of the mass balance series on Hintereisferner, Ötztal Alps, Austria: a detailed view into annual geodetic and glaciological observations

Reanalysis of a 10-year record (2004–2013) of seasonal mass balances at Langenferner/Vedretta Lunga, Ortler Alps, Italy

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