NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Springtime microwave emissivity changes in the southern Kara SeaSpringtime 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 circulations.
Document ID
19950052583
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Crane, Robert G.
(Pennsylvania State Univ. University Park, PA, United States)
Anderson, Mark R.
(Nebraska Univ. Lincoln, NE, United States)
Date Acquired
August 16, 2013
Publication Date
July 15, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: C7
ISSN: 0148-0227
Subject Category
Oceanography
Accession Number
95A84182
Funding Number(s)
CONTRACT_GRANT: NAGW-1042
CONTRACT_GRANT: NAGW-1266
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available