Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet
Light transmission into bare glacial ice affects surface energy balance, biophotochemistry, and light detection and ranging (lidar) laser elevation measurements but has not previously been reported for the Greenland Ice Sheet. We present measurements of spectral transmittance at 350–900 nm in bare g...
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ftdoajarticles:oai:doaj.org/article:7140e43160584fd7ac2b6e5c952db26e 2023-05-15T13:54:23+02:00 Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet M. G. Cooper L. C. Smith A. K. Rennermalm M. Tedesco R. Muthyala S. Z. Leidman S. E. Moustafa J. V. Fayne 2021-04-01T00:00:00Z https://doi.org/10.5194/tc-15-1931-2021 https://doaj.org/article/7140e43160584fd7ac2b6e5c952db26e EN eng Copernicus Publications https://tc.copernicus.org/articles/15/1931/2021/tc-15-1931-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-1931-2021 1994-0416 1994-0424 https://doaj.org/article/7140e43160584fd7ac2b6e5c952db26e The Cryosphere, Vol 15, Pp 1931-1953 (2021) Environmental sciences GE1-350 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.5194/tc-15-1931-2021 2022-12-31T05:39:07Z Light transmission into bare glacial ice affects surface energy balance, biophotochemistry, and light detection and ranging (lidar) laser elevation measurements but has not previously been reported for the Greenland Ice Sheet. We present measurements of spectral transmittance at 350–900 nm in bare glacial ice collected at a field site in the western Greenland ablation zone (67.15 ∘ N, 50.02 ∘ W). Empirical irradiance attenuation coefficients at 350–750 nm are ∼ 0.9–8.0 m −1 for ice at 12–124 cm depth. The absorption minimum is at ∼ 390–397 nm, in agreement with snow transmission measurements in Antarctica and optical mapping of deep ice at the South Pole. From 350–530 nm, our empirical attenuation coefficients are nearly 1 order of magnitude larger than theoretical values for optically pure ice. The estimated absorption coefficient at 400 nm suggests the ice volume contained a light-absorbing particle concentration equivalent to ∼ 1–2 parts per billion (ppb) of black carbon, which is similar to pre-industrial values found in remote polar snow. The equivalent mineral dust concentration is ∼ 300–600 ppb, which is similar to values for Northern Hemisphere warm periods with low aeolian activity inferred from ice cores. For a layer of quasi-granular white ice (weathering crust) extending from the surface to ∼ 10 cm depth, attenuation coefficients are 1.5 to 4 times larger than for deeper bubbly ice. Owing to higher attenuation in this layer of near-surface granular ice, optical penetration depth at 532 nm is 14 cm (20 %) lower than asymptotic attenuation lengths for optically pure bubbly ice. In addition to the traditional concept of light scattering on air bubbles, our results imply that the granular near-surface ice microstructure of weathering crust is an important control on radiative transfer in bare ice on the Greenland Ice Sheet ablation zone, and we provide new values of flux attenuation, absorption, and scattering coefficients to support model development and validation. Article in Journal/Newspaper Antarc* Antarctica Greenland Ice Sheet South pole South pole The Cryosphere Directory of Open Access Journals: DOAJ Articles Greenland South Pole The Cryosphere 15 4 1931 1953 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 M. G. Cooper L. C. Smith A. K. Rennermalm M. Tedesco R. Muthyala S. Z. Leidman S. E. Moustafa J. V. Fayne Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Light transmission into bare glacial ice affects surface energy balance, biophotochemistry, and light detection and ranging (lidar) laser elevation measurements but has not previously been reported for the Greenland Ice Sheet. We present measurements of spectral transmittance at 350–900 nm in bare glacial ice collected at a field site in the western Greenland ablation zone (67.15 ∘ N, 50.02 ∘ W). Empirical irradiance attenuation coefficients at 350–750 nm are ∼ 0.9–8.0 m −1 for ice at 12–124 cm depth. The absorption minimum is at ∼ 390–397 nm, in agreement with snow transmission measurements in Antarctica and optical mapping of deep ice at the South Pole. From 350–530 nm, our empirical attenuation coefficients are nearly 1 order of magnitude larger than theoretical values for optically pure ice. The estimated absorption coefficient at 400 nm suggests the ice volume contained a light-absorbing particle concentration equivalent to ∼ 1–2 parts per billion (ppb) of black carbon, which is similar to pre-industrial values found in remote polar snow. The equivalent mineral dust concentration is ∼ 300–600 ppb, which is similar to values for Northern Hemisphere warm periods with low aeolian activity inferred from ice cores. For a layer of quasi-granular white ice (weathering crust) extending from the surface to ∼ 10 cm depth, attenuation coefficients are 1.5 to 4 times larger than for deeper bubbly ice. Owing to higher attenuation in this layer of near-surface granular ice, optical penetration depth at 532 nm is 14 cm (20 %) lower than asymptotic attenuation lengths for optically pure bubbly ice. In addition to the traditional concept of light scattering on air bubbles, our results imply that the granular near-surface ice microstructure of weathering crust is an important control on radiative transfer in bare ice on the Greenland Ice Sheet ablation zone, and we provide new values of flux attenuation, absorption, and scattering coefficients to support model development and validation. |
format |
Article in Journal/Newspaper |
author |
M. G. Cooper L. C. Smith A. K. Rennermalm M. Tedesco R. Muthyala S. Z. Leidman S. E. Moustafa J. V. Fayne |
author_facet |
M. G. Cooper L. C. Smith A. K. Rennermalm M. Tedesco R. Muthyala S. Z. Leidman S. E. Moustafa J. V. Fayne |
author_sort |
M. G. Cooper |
title |
Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet |
title_short |
Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet |
title_full |
Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet |
title_fullStr |
Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet |
title_full_unstemmed |
Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet |
title_sort |
spectral attenuation coefficients from measurements of light transmission in bare ice on the greenland ice sheet |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-1931-2021 https://doaj.org/article/7140e43160584fd7ac2b6e5c952db26e |
geographic |
Greenland South Pole |
geographic_facet |
Greenland South Pole |
genre |
Antarc* Antarctica Greenland Ice Sheet South pole South pole The Cryosphere |
genre_facet |
Antarc* Antarctica Greenland Ice Sheet South pole South pole The Cryosphere |
op_source |
The Cryosphere, Vol 15, Pp 1931-1953 (2021) |
op_relation |
https://tc.copernicus.org/articles/15/1931/2021/tc-15-1931-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-1931-2021 1994-0416 1994-0424 https://doaj.org/article/7140e43160584fd7ac2b6e5c952db26e |
op_doi |
https://doi.org/10.5194/tc-15-1931-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
4 |
container_start_page |
1931 |
op_container_end_page |
1953 |
_version_ |
1766260143737012224 |