Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria
As Alpine glaciers become snow-free in summer, more dark, bare ice is exposed, decreasing local albedo and increasing surface melting. To include this feedback mechanism in models of future deglaciation, it is important to understand the processes governing broadband and spectral albedo at a local s...
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Online Access: | https://doi.org/10.5194/tc-14-4063-2020 https://tc.copernicus.org/articles/14/4063/2020/tc-14-4063-2020.pdf https://doaj.org/article/2d3382cde3f34d7ca1b09e539d0255f0 |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:2d3382cde3f34d7ca1b09e539d0255f0 2023-05-15T18:32:19+02:00 Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria L. Hartl L. Felbauer G. Schwaizer A. Fischer 2020-11-01 https://doi.org/10.5194/tc-14-4063-2020 https://tc.copernicus.org/articles/14/4063/2020/tc-14-4063-2020.pdf https://doaj.org/article/2d3382cde3f34d7ca1b09e539d0255f0 en eng Copernicus Publications doi:10.5194/tc-14-4063-2020 1994-0416 1994-0424 https://tc.copernicus.org/articles/14/4063/2020/tc-14-4063-2020.pdf https://doaj.org/article/2d3382cde3f34d7ca1b09e539d0255f0 undefined The Cryosphere, Vol 14, Pp 4063-4081 (2020) geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2020 fttriple https://doi.org/10.5194/tc-14-4063-2020 2023-01-22T19:30:54Z As Alpine glaciers become snow-free in summer, more dark, bare ice is exposed, decreasing local albedo and increasing surface melting. To include this feedback mechanism in models of future deglaciation, it is important to understand the processes governing broadband and spectral albedo at a local scale. However, few in situ reflectance data have been measured in the ablation zones of mountain glaciers. As a contribution to this knowledge gap, we present spectral reflectance data (hemispherical–conical–reflectance factor) from 325 to 1075 nm collected along several profile lines in the ablation zone of Jamtalferner, Austria. Measurements were timed to closely coincide with a Sentinel-2 and Landsat 8 overpass and are compared to the respective ground reflectance (bottom-of-atmosphere) products. The brightest spectra have a maximum reflectance of up to 0.7 and consist of clean, dry ice. In contrast, reflectance does not exceed 0.2 for dark spectra where liquid water and/or fine-grained debris are present. Spectra can roughly be grouped into dry ice, wet ice, and dirt or rocks, although gradations between these groups occur. Neither satellite captures the full range of in situ reflectance values. The difference between ground and satellite data is not uniform across satellite bands, between Landsat and Sentinel, and to some extent between ice surface types (underestimation of reflectance for bright surfaces, overestimation for dark surfaces). We highlight the need for further, systematic measurements of in situ spectral reflectance properties, their variability in time and space, and in-depth analysis of time-synchronous satellite data. Article in Journal/Newspaper The Cryosphere Unknown The Cryosphere 14 11 4063 4081 |
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geo envir L. Hartl L. Felbauer G. Schwaizer A. Fischer Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria |
topic_facet |
geo envir |
description |
As Alpine glaciers become snow-free in summer, more dark, bare ice is exposed, decreasing local albedo and increasing surface melting. To include this feedback mechanism in models of future deglaciation, it is important to understand the processes governing broadband and spectral albedo at a local scale. However, few in situ reflectance data have been measured in the ablation zones of mountain glaciers. As a contribution to this knowledge gap, we present spectral reflectance data (hemispherical–conical–reflectance factor) from 325 to 1075 nm collected along several profile lines in the ablation zone of Jamtalferner, Austria. Measurements were timed to closely coincide with a Sentinel-2 and Landsat 8 overpass and are compared to the respective ground reflectance (bottom-of-atmosphere) products. The brightest spectra have a maximum reflectance of up to 0.7 and consist of clean, dry ice. In contrast, reflectance does not exceed 0.2 for dark spectra where liquid water and/or fine-grained debris are present. Spectra can roughly be grouped into dry ice, wet ice, and dirt or rocks, although gradations between these groups occur. Neither satellite captures the full range of in situ reflectance values. The difference between ground and satellite data is not uniform across satellite bands, between Landsat and Sentinel, and to some extent between ice surface types (underestimation of reflectance for bright surfaces, overestimation for dark surfaces). We highlight the need for further, systematic measurements of in situ spectral reflectance properties, their variability in time and space, and in-depth analysis of time-synchronous satellite data. |
format |
Article in Journal/Newspaper |
author |
L. Hartl L. Felbauer G. Schwaizer A. Fischer |
author_facet |
L. Hartl L. Felbauer G. Schwaizer A. Fischer |
author_sort |
L. Hartl |
title |
Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria |
title_short |
Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria |
title_full |
Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria |
title_fullStr |
Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria |
title_full_unstemmed |
Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria |
title_sort |
small-scale spatial variability in bare-ice reflectance at jamtalferner, austria |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-4063-2020 https://tc.copernicus.org/articles/14/4063/2020/tc-14-4063-2020.pdf https://doaj.org/article/2d3382cde3f34d7ca1b09e539d0255f0 |
genre |
The Cryosphere |
genre_facet |
The Cryosphere |
op_source |
The Cryosphere, Vol 14, Pp 4063-4081 (2020) |
op_relation |
doi:10.5194/tc-14-4063-2020 1994-0416 1994-0424 https://tc.copernicus.org/articles/14/4063/2020/tc-14-4063-2020.pdf https://doaj.org/article/2d3382cde3f34d7ca1b09e539d0255f0 |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/tc-14-4063-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
11 |
container_start_page |
4063 |
op_container_end_page |
4081 |
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