Microwave sea ice and ocean brightness temperature and emissivity between 22 and 243 GHz from ship-based radiometers
Passive microwave measurements of Arctic sea ice have been conducted over the last 50 years from space and during airborne, ship- and ground-based measurement campaigns. The different radiometric signatures of distinct surface types have led to satellite retrievals of, e.g., sea-ice concentration. I...
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| Format: | Article |
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Cambridge University Press
2025-01-01
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| Series: | Annals of Glaciology |
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| Online Access: | https://www.cambridge.org/core/product/identifier/S0260305525000011/type/journal_article |
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| author | Janna E. Rückert Andreas Walbröl Nils Risse Pavel Krobot Rainer Haseneder-Lind Mario Mech Kerstin Ebell Gunnar Spreen |
| author_facet | Janna E. Rückert Andreas Walbröl Nils Risse Pavel Krobot Rainer Haseneder-Lind Mario Mech Kerstin Ebell Gunnar Spreen |
| author_sort | Janna E. Rückert |
| collection | DOAJ |
| description | Passive microwave measurements of Arctic sea ice have been conducted over the last 50 years from space and during airborne, ship- and ground-based measurement campaigns. The different radiometric signatures of distinct surface types have led to satellite retrievals of, e.g., sea-ice concentration. In contrast, ground-based upward-viewing radiometers measure radiation emitted from the atmosphere and are used to retrieve atmospheric variables. Here, we present results from a ship-based radiometer setup with a mirror construction, which allows us to switch between atmospheric and surface measurements flexibly. This way, in summer 2022, surface observations in the Arctic marginal sea-ice zone could be performed from the research vessel Polarstern by two radiometers covering the frequency range from 22 to 243 GHz. At low frequencies, the brightness temperatures show clear signatures of different surface conditions. We estimate emissivities at 53∘ zenith angle from infrared-based skin temperatures. Predominantly vertically polarized 22–31 GHz emissivities are between 0.51 and 0.55 for open ocean and around 0.95 for sea ice. Predominantly horizontally polarized 243 GHz ocean emissivities are around 0.78 and ice surfaces exhibit a large variability from 0.67 to 0.82. Our results can improve the characterization of surface emissions in satellite retrieval algorithms. |
| format | Article |
| id | doaj-art-110dd9723a79459284006f286151eb71 |
| institution | Kabale University |
| issn | 0260-3055 1727-5644 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Cambridge University Press |
| record_format | Article |
| series | Annals of Glaciology |
| spelling | doaj-art-110dd9723a79459284006f286151eb712025-02-10T08:40:42ZengCambridge University PressAnnals of Glaciology0260-30551727-56442025-01-016610.1017/aog.2025.1Microwave sea ice and ocean brightness temperature and emissivity between 22 and 243 GHz from ship-based radiometersJanna E. Rückert0https://orcid.org/0000-0001-9885-6576Andreas Walbröl1Nils Risse2Pavel Krobot3Rainer Haseneder-Lind4Mario Mech5Kerstin Ebell6Gunnar Spreen7https://orcid.org/0000-0003-0165-8448Institute of Environmental Physics, University of Bremen, Bremen, GermanyInstitute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyInstitute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyInstitute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyInstitute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyInstitute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyInstitute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyInstitute of Environmental Physics, University of Bremen, Bremen, GermanyPassive microwave measurements of Arctic sea ice have been conducted over the last 50 years from space and during airborne, ship- and ground-based measurement campaigns. The different radiometric signatures of distinct surface types have led to satellite retrievals of, e.g., sea-ice concentration. In contrast, ground-based upward-viewing radiometers measure radiation emitted from the atmosphere and are used to retrieve atmospheric variables. Here, we present results from a ship-based radiometer setup with a mirror construction, which allows us to switch between atmospheric and surface measurements flexibly. This way, in summer 2022, surface observations in the Arctic marginal sea-ice zone could be performed from the research vessel Polarstern by two radiometers covering the frequency range from 22 to 243 GHz. At low frequencies, the brightness temperatures show clear signatures of different surface conditions. We estimate emissivities at 53∘ zenith angle from infrared-based skin temperatures. Predominantly vertically polarized 22–31 GHz emissivities are between 0.51 and 0.55 for open ocean and around 0.95 for sea ice. Predominantly horizontally polarized 243 GHz ocean emissivities are around 0.78 and ice surfaces exhibit a large variability from 0.67 to 0.82. Our results can improve the characterization of surface emissions in satellite retrieval algorithms.https://www.cambridge.org/core/product/identifier/S0260305525000011/type/journal_articleArcticbrightness temperaturemicrowave radiometryremote sensingsea ice |
| spellingShingle | Janna E. Rückert Andreas Walbröl Nils Risse Pavel Krobot Rainer Haseneder-Lind Mario Mech Kerstin Ebell Gunnar Spreen Microwave sea ice and ocean brightness temperature and emissivity between 22 and 243 GHz from ship-based radiometers Annals of Glaciology Arctic brightness temperature microwave radiometry remote sensing sea ice |
| title | Microwave sea ice and ocean brightness temperature and emissivity between 22 and 243 GHz from ship-based radiometers |
| title_full | Microwave sea ice and ocean brightness temperature and emissivity between 22 and 243 GHz from ship-based radiometers |
| title_fullStr | Microwave sea ice and ocean brightness temperature and emissivity between 22 and 243 GHz from ship-based radiometers |
| title_full_unstemmed | Microwave sea ice and ocean brightness temperature and emissivity between 22 and 243 GHz from ship-based radiometers |
| title_short | Microwave sea ice and ocean brightness temperature and emissivity between 22 and 243 GHz from ship-based radiometers |
| title_sort | microwave sea ice and ocean brightness temperature and emissivity between 22 and 243 ghz from ship based radiometers |
| topic | Arctic brightness temperature microwave radiometry remote sensing sea ice |
| url | https://www.cambridge.org/core/product/identifier/S0260305525000011/type/journal_article |
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