Springtime Microwave Emissivity Changes in the Southern Kara Sea
Springtime microwave brightness temperatures over first-year ice are examined for the southern Kara Sea. Snow emissivity changes are revealed by episodic drops in the 37- to 18-GHz brightness temperature gradient ratio measured by the Nimbus 7 scanning multichannel microwave radiometer. We suggest t...
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DigitalCommons@University of Nebraska - Lincoln
1994
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ftunivnebraskali:oai:digitalcommons.unl.edu:geosciencefacpub-1181 2023-11-12T04:17:57+01:00 Springtime Microwave Emissivity Changes in the Southern Kara Sea Crane, Robert G. Anderson, Mark R. 1994-07-15T07:00:00Z application/pdf https://digitalcommons.unl.edu/geosciencefacpub/180 https://digitalcommons.unl.edu/context/geosciencefacpub/article/1181/viewcontent/Anderson_1994_JGR_Springtime_Microwave_Emissivity_Changes_in_the_Southern_Kara_Sea.pdf unknown DigitalCommons@University of Nebraska - Lincoln https://digitalcommons.unl.edu/geosciencefacpub/180 https://digitalcommons.unl.edu/context/geosciencefacpub/article/1181/viewcontent/Anderson_1994_JGR_Springtime_Microwave_Emissivity_Changes_in_the_Southern_Kara_Sea.pdf Papers in the Earth and Atmospheric Sciences Earth Sciences text 1994 ftunivnebraskali 2023-10-30T10:44:33Z Springtime microwave brightness temperatures over first-year ice are examined for the southern Kara Sea. Snow emissivity changes are revealed by episodic drops in the 37- to 18-GHz brightness temperature gradient ratio measured by the Nimbus 7 scanning multichannel microwave radiometer. We suggest that the negative gradient ratios in spring 1982 result from increased scatter at 37 GHz due to the formation of a near-surface hoar layer. This interpretation is supported by the results of a surface radiation balance model that shows the melt signature occurring at below freezing temperatures but under clear-sky conditions with increased solar input to the surface. Published observations from the Greenland ice cap show a surface hoar layer forming under similar atmospheric conditions owing to the increased penetration and absorption of solar radiation just below the surface layer. In spring/early summer 1984 similar gradient ratio signatures occur. They appear to be due to several days of freeze-thaw cycling following the movement of a low-pressure system through the region. These changes in surface emissivity represent the transition from winter to summer conditions (as defined by the microwave response) and are shown to be regional in extent and to vary with the synoptic circulation. Text Greenland Ice cap Kara Sea University of Nebraska-Lincoln: DigitalCommons@UNL Kara Sea Greenland |
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Open Polar |
collection |
University of Nebraska-Lincoln: DigitalCommons@UNL |
op_collection_id |
ftunivnebraskali |
language |
unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Crane, Robert G. Anderson, Mark R. Springtime Microwave Emissivity Changes in the Southern Kara Sea |
topic_facet |
Earth Sciences |
description |
Springtime microwave brightness temperatures over first-year ice are examined for the southern Kara Sea. Snow emissivity changes are revealed by episodic drops in the 37- to 18-GHz brightness temperature gradient ratio measured by the Nimbus 7 scanning multichannel microwave radiometer. We suggest that the negative gradient ratios in spring 1982 result from increased scatter at 37 GHz due to the formation of a near-surface hoar layer. This interpretation is supported by the results of a surface radiation balance model that shows the melt signature occurring at below freezing temperatures but under clear-sky conditions with increased solar input to the surface. Published observations from the Greenland ice cap show a surface hoar layer forming under similar atmospheric conditions owing to the increased penetration and absorption of solar radiation just below the surface layer. In spring/early summer 1984 similar gradient ratio signatures occur. They appear to be due to several days of freeze-thaw cycling following the movement of a low-pressure system through the region. These changes in surface emissivity represent the transition from winter to summer conditions (as defined by the microwave response) and are shown to be regional in extent and to vary with the synoptic circulation. |
format |
Text |
author |
Crane, Robert G. Anderson, Mark R. |
author_facet |
Crane, Robert G. Anderson, Mark R. |
author_sort |
Crane, Robert G. |
title |
Springtime Microwave Emissivity Changes in the Southern Kara Sea |
title_short |
Springtime Microwave Emissivity Changes in the Southern Kara Sea |
title_full |
Springtime Microwave Emissivity Changes in the Southern Kara Sea |
title_fullStr |
Springtime Microwave Emissivity Changes in the Southern Kara Sea |
title_full_unstemmed |
Springtime Microwave Emissivity Changes in the Southern Kara Sea |
title_sort |
springtime microwave emissivity changes in the southern kara sea |
publisher |
DigitalCommons@University of Nebraska - Lincoln |
publishDate |
1994 |
url |
https://digitalcommons.unl.edu/geosciencefacpub/180 https://digitalcommons.unl.edu/context/geosciencefacpub/article/1181/viewcontent/Anderson_1994_JGR_Springtime_Microwave_Emissivity_Changes_in_the_Southern_Kara_Sea.pdf |
geographic |
Kara Sea Greenland |
geographic_facet |
Kara Sea Greenland |
genre |
Greenland Ice cap Kara Sea |
genre_facet |
Greenland Ice cap Kara Sea |
op_source |
Papers in the Earth and Atmospheric Sciences |
op_relation |
https://digitalcommons.unl.edu/geosciencefacpub/180 https://digitalcommons.unl.edu/context/geosciencefacpub/article/1181/viewcontent/Anderson_1994_JGR_Springtime_Microwave_Emissivity_Changes_in_the_Southern_Kara_Sea.pdf |
_version_ |
1782334698519789568 |