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Mapping freeze/thaw boundaries with SMMR dataNimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) data are used to map daily freeze/thaw patterns in the upper Midwest for the Fall of 1984. The combination of a low 37 GHz radiobrightness and a negative 10.7, 18, and 37 GHz spectral gradient, Partial Derivative of Tb with Respect to f, appears to be an effective discriminant for classifying soil as frozen or thawed. The 37 GHz emissivity is less sensitive to soil moisture than are the lower frequency emissivities so that the 37 GHz radiobrightness appears to track soil surface temperature relatively well. The negative gradient for frozen ground is a consequence of volume scatter darkening at shorter microwave wavelengths. This shorter wavelength darkening is not seen in thawed moist soils.
Document ID
19890014590
Document Type
Contractor Report (CR)
Authors
Zuerndorfer, B. W.
(Michigan Univ. Ann Arbor, MI, United States)
England, A. W.
(Michigan Univ. Ann Arbor, MI, United States)
Dobson, M. C.
(Michigan Univ. Ann Arbor, MI, United States)
Ulaby, F. T.
(Michigan Univ. Ann Arbor, MI, United States)
Date Acquired
September 5, 2013
Publication Date
January 1, 1989
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
NAS 1.26:184991
NASA-CR-184991
Accession Number
89N23961
Funding Number(s)
CONTRACT_GRANT: NAG5-852
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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