Snow grain-size profiles deduced from microwave snow emissivities in Antarctica
International audience Spaceborne microwave radiometers are an attractive tool for observing Antarctic climate because their measurements are related to the snow temperature. However, the conversion from microwave emission to snow temperature is not simple and strongly depends on the emissivity thro...
Published in: | Journal of Glaciology |
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Main Authors: | , , |
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Format: | Article in Journal/Newspaper |
Language: | English |
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HAL CCSD
2010
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Online Access: | https://insu.hal.science/insu-00554199 https://insu.hal.science/insu-00554199/document https://insu.hal.science/insu-00554199/file/snow-grain-size-profiles-deduced-from-microwave-snow-emissivities-in-antarctica.pdf https://doi.org/10.3189/002214310792447806 |
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Open Polar |
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Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
English |
topic |
[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
spellingShingle |
[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology Brucker, L. Picard, G. Fily, M. Snow grain-size profiles deduced from microwave snow emissivities in Antarctica |
topic_facet |
[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
description |
International audience Spaceborne microwave radiometers are an attractive tool for observing Antarctic climate because their measurements are related to the snow temperature. However, the conversion from microwave emission to snow temperature is not simple and strongly depends on the emissivity through snow properties. This difficulty in predicting the snow property profile for Antarctic conditions is the main bottleneck in the retrieval of accurate climate information from microwave radiometers. We attempt to explain the vertically polarized emissivity at 19.3 and 37 GHz derived from brightness temperatures acquired by the Special Sensor Microwave/Imager (SSM/I) and physical temperature from the ERA-40 re-analysis. In Antarctica the snow emissivities at 19.3 and 37 GHz are nearly equal, although a decrease with frequency is expected. To explain this, we consider various profiles of snow grain size and density and predict their emissivity using a dense-medium radiative transfer (DMRT) model. The results show that the emissivities cannot be explained by constant profiles of grain size and density. Heterogeneous snowpacks need to be considered. We first test random variations of snow density and grain radius with depth and then monotonic and continuous variations in the snow grain radius. In both cases, we show that an overall increase of the snow grain radius with depth is required to match the observed emissivity in Antarctica. In addition, two parameters characterizing the snow grain profiles are retrieved and compared with (1) in situ measurements of grain size at various locations in East Antarctica, (2) grain size estimated using visible spaceborne radiometers and (3) a semi-empirical relationship for grain growth. |
author2 |
Laboratoire de glaciologie et géophysique de l'environnement (LGGE) Observatoire des Sciences de l'Univers de Grenoble (OSUG) Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS) CLIPS Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG) |
format |
Article in Journal/Newspaper |
author |
Brucker, L. Picard, G. Fily, M. |
author_facet |
Brucker, L. Picard, G. Fily, M. |
author_sort |
Brucker, L. |
title |
Snow grain-size profiles deduced from microwave snow emissivities in Antarctica |
title_short |
Snow grain-size profiles deduced from microwave snow emissivities in Antarctica |
title_full |
Snow grain-size profiles deduced from microwave snow emissivities in Antarctica |
title_fullStr |
Snow grain-size profiles deduced from microwave snow emissivities in Antarctica |
title_full_unstemmed |
Snow grain-size profiles deduced from microwave snow emissivities in Antarctica |
title_sort |
snow grain-size profiles deduced from microwave snow emissivities in antarctica |
publisher |
HAL CCSD |
publishDate |
2010 |
url |
https://insu.hal.science/insu-00554199 https://insu.hal.science/insu-00554199/document https://insu.hal.science/insu-00554199/file/snow-grain-size-profiles-deduced-from-microwave-snow-emissivities-in-antarctica.pdf https://doi.org/10.3189/002214310792447806 |
genre |
Antarc* Antarctic Antarctica East Antarctica Journal of Glaciology |
genre_facet |
Antarc* Antarctic Antarctica East Antarctica Journal of Glaciology |
op_source |
ISSN: 0022-1430 EISSN: 1727-5652 Journal of Glaciology https://insu.hal.science/insu-00554199 Journal of Glaciology, 2010, 56 (197), pp.514-526. ⟨10.3189/002214310792447806⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.3189/002214310792447806 insu-00554199 https://insu.hal.science/insu-00554199 https://insu.hal.science/insu-00554199/document https://insu.hal.science/insu-00554199/file/snow-grain-size-profiles-deduced-from-microwave-snow-emissivities-in-antarctica.pdf BIBCODE: 10.3189/002214310792447806 doi:10.3189/002214310792447806 |
op_rights |
http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.3189/002214310792447806 |
container_title |
Journal of Glaciology |
container_volume |
56 |
container_issue |
197 |
container_start_page |
514 |
op_container_end_page |
526 |
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1797568394701045760 |
spelling |
ftinsu:oai:HAL:insu-00554199v1 2024-04-28T07:58:14+00:00 Snow grain-size profiles deduced from microwave snow emissivities in Antarctica Brucker, L. Picard, G. Fily, M. Laboratoire de glaciologie et géophysique de l'environnement (LGGE) Observatoire des Sciences de l'Univers de Grenoble (OSUG) Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS) CLIPS Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG) 2010-08 https://insu.hal.science/insu-00554199 https://insu.hal.science/insu-00554199/document https://insu.hal.science/insu-00554199/file/snow-grain-size-profiles-deduced-from-microwave-snow-emissivities-in-antarctica.pdf https://doi.org/10.3189/002214310792447806 en eng HAL CCSD International Glaciological Society info:eu-repo/semantics/altIdentifier/doi/10.3189/002214310792447806 insu-00554199 https://insu.hal.science/insu-00554199 https://insu.hal.science/insu-00554199/document https://insu.hal.science/insu-00554199/file/snow-grain-size-profiles-deduced-from-microwave-snow-emissivities-in-antarctica.pdf BIBCODE: 10.3189/002214310792447806 doi:10.3189/002214310792447806 http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess ISSN: 0022-1430 EISSN: 1727-5652 Journal of Glaciology https://insu.hal.science/insu-00554199 Journal of Glaciology, 2010, 56 (197), pp.514-526. ⟨10.3189/002214310792447806⟩ [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology info:eu-repo/semantics/article Journal articles 2010 ftinsu https://doi.org/10.3189/002214310792447806 2024-04-05T00:35:45Z International audience Spaceborne microwave radiometers are an attractive tool for observing Antarctic climate because their measurements are related to the snow temperature. However, the conversion from microwave emission to snow temperature is not simple and strongly depends on the emissivity through snow properties. This difficulty in predicting the snow property profile for Antarctic conditions is the main bottleneck in the retrieval of accurate climate information from microwave radiometers. We attempt to explain the vertically polarized emissivity at 19.3 and 37 GHz derived from brightness temperatures acquired by the Special Sensor Microwave/Imager (SSM/I) and physical temperature from the ERA-40 re-analysis. In Antarctica the snow emissivities at 19.3 and 37 GHz are nearly equal, although a decrease with frequency is expected. To explain this, we consider various profiles of snow grain size and density and predict their emissivity using a dense-medium radiative transfer (DMRT) model. The results show that the emissivities cannot be explained by constant profiles of grain size and density. Heterogeneous snowpacks need to be considered. We first test random variations of snow density and grain radius with depth and then monotonic and continuous variations in the snow grain radius. In both cases, we show that an overall increase of the snow grain radius with depth is required to match the observed emissivity in Antarctica. In addition, two parameters characterizing the snow grain profiles are retrieved and compared with (1) in situ measurements of grain size at various locations in East Antarctica, (2) grain size estimated using visible spaceborne radiometers and (3) a semi-empirical relationship for grain growth. Article in Journal/Newspaper Antarc* Antarctic Antarctica East Antarctica Journal of Glaciology Institut national des sciences de l'Univers: HAL-INSU Journal of Glaciology 56 197 514 526 |