Examples of ice pack rigidity and mobility characteristics determined from ice motion |
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| Authors: | Dr James K Lewis Ronald E Englebretson Dr Warren W Denner |
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| Institution: | (1) Science Applications International Corporation, 1304 Deacon, 77840 College Station, TX, USA;(2) Science Applications International Corporation, 205 Montecito Avenue, 93940 Monterey, CA, USA |
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| Abstract: | A method has been developed to determine ice pack rigidity and mobility using observed ice motion. Using this method, one may determine how solidly the ice pack is frozen in near real-time. In addition, spatial and temporal variations in the freezing and thawing of the ice pack can be studied. Various degrees of ice rigidity were considered using remotely-sensed ice motion off the N coast of Alaska during 1975 and 1979. Summer-time ice rigidities were detected first in late June 1975 and lasted through September 1975. However, in 1979 considerably higher rigidities were found in August while summer-like rigidities were detected into late November. Analyses of atmospheric pressure distributions suggest that less mechanical breakup occurred in the summer of 1979, resulting in the greater rigidities during August of that year. In addition, minimum ice coverage was 21% less in the Beaufort Sea in 1979 than in 1975. The result was a relatively large percent of thinner ice for November of 1979 than for 1975, the likely cause of the less rigid conditions detected during the fall of 1979.Nomenclature D
deviation in height (m) of a pressure level from the standard atmosphere (Huschke 1959).
- eT
time lag (h) at which the autocorrelation of ice speed drops to e–1
- SL
the large-scale disturbance or longwave component of a scalar field; in this study, the 500 mb circulation (Holl 1963).
- U
mean ice speed over a given time interval
- V
variance of ice speed over a given time interval |
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