Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland
Deposition of small amounts of airborne dust on glaciers causes positive radiative forcing and enhanced melting due to the reduction of surface albedo. To study the effects of dust deposition on the mass balance of Brúarjökull, an outlet glacier of the largest ice cap in Iceland, Vatnajökull, a stud...
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ftcopernicus:oai:publications.copernicus.org:tc54515 2023-05-15T16:21:39+02:00 Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland Wittmann, Monika Groot Zwaaftink, Christine Dorothea Steffensen Schmidt, Louise Guðmundsson, Sverrir Pálsson, Finnur Arnalds, Olafur Björnsson, Helgi Thorsteinsson, Throstur Stohl, Andreas 2018-09-27 application/pdf https://doi.org/10.5194/tc-11-741-2017 https://tc.copernicus.org/articles/11/741/2017/ eng eng doi:10.5194/tc-11-741-2017 https://tc.copernicus.org/articles/11/741/2017/ eISSN: 1994-0424 Text 2018 ftcopernicus https://doi.org/10.5194/tc-11-741-2017 2020-07-20T16:23:47Z Deposition of small amounts of airborne dust on glaciers causes positive radiative forcing and enhanced melting due to the reduction of surface albedo. To study the effects of dust deposition on the mass balance of Brúarjökull, an outlet glacier of the largest ice cap in Iceland, Vatnajökull, a study of dust deposition events in the year 2012 was carried out. The dust-mobilisation module FLEXDUST was used to calculate spatio-temporally resolved dust emissions from Iceland and the dispersion model FLEXPART was used to simulate atmospheric dust dispersion and deposition. We used albedo measurements at two automatic weather stations on Brúarjökull to evaluate the dust impacts. Both stations are situated in the accumulation area of the glacier, but the lower station is close to the equilibrium line. For this site ( ∼ 1210 m a.s.l.), the dispersion model produced 10 major dust deposition events and a total annual deposition of 20.5 g m −2 . At the station located higher on the glacier ( ∼ 1525 m a.s.l.), the model produced nine dust events, with one single event causing ∼ 5 g m −2 of dust deposition and a total deposition of ∼ 10 g m −2 yr −1 . The main dust source was found to be the Dyngjusandur floodplain north of Vatnajökull; northerly winds prevailed 80 % of the time at the lower station when dust events occurred. In all of the simulated dust events, a corresponding albedo drop was observed at the weather stations. The influence of the dust on the albedo was estimated using the regional climate model HIRHAM5 to simulate the albedo of a clean glacier surface without dust. By comparing the measured albedo to the modelled albedo, we determine the influence of dust events on the snow albedo and the surface energy balance. We estimate that the dust deposition caused an additional 1.1 m w.e. (water equivalent) of snowmelt (or 42 % of the 2.8 m w.e. total melt) compared to a hypothetical clean glacier surface at the lower station, and 0.6 m w.e. more melt (or 38 % of the 1.6 m w.e. melt in total) at the station located further upglacier. Our findings show that dust has a strong influence on the mass balance of glaciers in Iceland. Text glacier Ice cap Iceland Vatnajökull Copernicus Publications: E-Journals Brúarjökull ENVELOPE(-16.157,-16.157,64.682,64.682) Vatnajökull ENVELOPE(-16.823,-16.823,64.420,64.420) The Cryosphere 11 2 741 754 |
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Open Polar |
collection |
Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Deposition of small amounts of airborne dust on glaciers causes positive radiative forcing and enhanced melting due to the reduction of surface albedo. To study the effects of dust deposition on the mass balance of Brúarjökull, an outlet glacier of the largest ice cap in Iceland, Vatnajökull, a study of dust deposition events in the year 2012 was carried out. The dust-mobilisation module FLEXDUST was used to calculate spatio-temporally resolved dust emissions from Iceland and the dispersion model FLEXPART was used to simulate atmospheric dust dispersion and deposition. We used albedo measurements at two automatic weather stations on Brúarjökull to evaluate the dust impacts. Both stations are situated in the accumulation area of the glacier, but the lower station is close to the equilibrium line. For this site ( ∼ 1210 m a.s.l.), the dispersion model produced 10 major dust deposition events and a total annual deposition of 20.5 g m −2 . At the station located higher on the glacier ( ∼ 1525 m a.s.l.), the model produced nine dust events, with one single event causing ∼ 5 g m −2 of dust deposition and a total deposition of ∼ 10 g m −2 yr −1 . The main dust source was found to be the Dyngjusandur floodplain north of Vatnajökull; northerly winds prevailed 80 % of the time at the lower station when dust events occurred. In all of the simulated dust events, a corresponding albedo drop was observed at the weather stations. The influence of the dust on the albedo was estimated using the regional climate model HIRHAM5 to simulate the albedo of a clean glacier surface without dust. By comparing the measured albedo to the modelled albedo, we determine the influence of dust events on the snow albedo and the surface energy balance. We estimate that the dust deposition caused an additional 1.1 m w.e. (water equivalent) of snowmelt (or 42 % of the 2.8 m w.e. total melt) compared to a hypothetical clean glacier surface at the lower station, and 0.6 m w.e. more melt (or 38 % of the 1.6 m w.e. melt in total) at the station located further upglacier. Our findings show that dust has a strong influence on the mass balance of glaciers in Iceland. |
format |
Text |
author |
Wittmann, Monika Groot Zwaaftink, Christine Dorothea Steffensen Schmidt, Louise Guðmundsson, Sverrir Pálsson, Finnur Arnalds, Olafur Björnsson, Helgi Thorsteinsson, Throstur Stohl, Andreas |
spellingShingle |
Wittmann, Monika Groot Zwaaftink, Christine Dorothea Steffensen Schmidt, Louise Guðmundsson, Sverrir Pálsson, Finnur Arnalds, Olafur Björnsson, Helgi Thorsteinsson, Throstur Stohl, Andreas Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland |
author_facet |
Wittmann, Monika Groot Zwaaftink, Christine Dorothea Steffensen Schmidt, Louise Guðmundsson, Sverrir Pálsson, Finnur Arnalds, Olafur Björnsson, Helgi Thorsteinsson, Throstur Stohl, Andreas |
author_sort |
Wittmann, Monika |
title |
Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland |
title_short |
Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland |
title_full |
Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland |
title_fullStr |
Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland |
title_full_unstemmed |
Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland |
title_sort |
impact of dust deposition on the albedo of vatnajökull ice cap, iceland |
publishDate |
2018 |
url |
https://doi.org/10.5194/tc-11-741-2017 https://tc.copernicus.org/articles/11/741/2017/ |
long_lat |
ENVELOPE(-16.157,-16.157,64.682,64.682) ENVELOPE(-16.823,-16.823,64.420,64.420) |
geographic |
Brúarjökull Vatnajökull |
geographic_facet |
Brúarjökull Vatnajökull |
genre |
glacier Ice cap Iceland Vatnajökull |
genre_facet |
glacier Ice cap Iceland Vatnajökull |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-11-741-2017 https://tc.copernicus.org/articles/11/741/2017/ |
op_doi |
https://doi.org/10.5194/tc-11-741-2017 |
container_title |
The Cryosphere |
container_volume |
11 |
container_issue |
2 |
container_start_page |
741 |
op_container_end_page |
754 |
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1766009642212655104 |