摘要: A method has been developed to determine ice pack rigidity and mobility using observed ice motion. With this method, one may determine how solidly the ice pack is frozen in near real-time. Spatial and temporal variations in the fr... 展开 A method has been developed to determine ice pack rigidity and mobility using observed ice motion. With this method, one may determine how solidly the ice pack is frozen in near real-time. Spatial and temporal variations in the freezing and thawing of the ice pack can also be studied. This method was developed to study how well numerical ice modeling techniques were reproducing actual sea ice processes. The ice pack rigidity parameter is now being used to compare observed periods of ice pack thawing and freezing with model from the same regions and times. Various degrees of ice rigidity and mobility were studied using remotely-sensed ice motion data off the north coast of Alaska during 1975 and 1979. Characteristics of the time histories of pack ice speed were used to infer changes in the rigidity of pack ice. Summer-time ice rigidities were detected first in late June 1975 and lasted through September. 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. Minimum ice coverage was 20% less in the Beaufort Sea in 1979 than in 1975 resulting in a relatively large percent of thinner ice for November of 1979 than for 1975, the likely cause of the less rigid conditions in the fall of 1979. 收起