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  • ENVIRONMENT POLLUTION  (2)
  • 1
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    A C-band backscatter model for lake ice in Alaska (1993)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: ERS-1 SAR imagery of lake ice growing on shallow tundra lakes in northern Alaska shows interesting radar backscatter variations. Based on the analysis of ice cores from these lakes, a multi-layer backscatter model comprised of the following elements has been developed: (1) specular air-ice; ice-water and ice-frozen soil boundaries; (2) an ice layer of variable thickness; (3) ice sub-layers with air inclusions of variable density, size and shape including spheres, prolate spheroids, and cylinders of finite length. Preliminary model results confirm that backscatter is a sensitive function of greater reflectivity than from an ice-frozen soil interface. The model has also been tested using bubble data derived from ice cores in April 1992. The modelled backscatter is compared with backscatter derived from ERS-1 SAR images obtained at the same time as the fieldwork.
    Keywords: ENVIRONMENT POLLUTION
    Type: NASA-CR-199628 , NAS 1.26:199628 , IEEE-93CH3294-6 , LC-93-77594 , NIPS-95-05487 , 1993 International Geoscience and Remote Sensing Symposium (IGARSS 1993). Better Understanding of Earth Environment, Volume 3; Aug 18, 1993 - Aug 21, 1993; Tokyo; Japan
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    ERS-1 SAR backscatter changes associated with ice growing on shallow lakes in Arctic Alaska (1993)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Spatial and temporal backscatter intensity (sigma(sup o)) variations from ice growing on shallow lakes during winter 1991-92 near Barrow, NW Alaska, have been quantified for the first time using ERS-I C-band SAR data acquired at the Alaska SAR Facility. A field and laboratory validation program, including measurements of the thickness and structure-stratigraphy of the ice, indicates that sigma(sup o) values are strongly dependent on whether the ice freezes to the lake bottom, or remains afloat. Backscatter intensity decreases significantly when the ice grounds on the bottom. Strong backscatter from floating ice is attributed to a specular ice-water interface and vertically oriented tubular bubbles. During the spring thaw, backscatter undergoes a reversal; sigma(sup o) values from ice that was grounded increase, while sigma(sup o) values from ice that was afloat decrease. This phenomenon has not previously been reported.
    Keywords: ENVIRONMENT POLLUTION
    Type: NASA-CR-199629 , NIPS-95-05488 , NAS 1.26:199629 , IEEE-93CH3294-6 , 1993 International Geoscience and Remote Sensing Symposium (IGARSS 1993). Better Understanding of Earth Environment, Volume 4; Aug 18, 1993 - Aug 21, 1993; Tokyo; Japan
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
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