Physical Properties of Icebergs. Part I. Height to Draft Ratios of Icebergs. Part II. Mass Estimation of Arctic Icebergs.
COAST GUARD RESEARCH AND DEVELOPMENT CENTER GROTON CONN
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A study of height to draft ratios of icebergs near the Davis Strait reveals ratios which range from 11.28 to 110.56. The ratios of bergs dominated by their horizontal dimension, such as tabular or broken tabular icebergs, have average height to draft ratios of 14.46 and 14.26 respectively. Bergs with a more vertical nature, pinnacle or drydock bergs, have ratios averaging 12.31 and 12.41 respectively. The smallest ratios are found in domed bergs which average 16.30. If we assume that the height to draft ratio of icebergs is characterized by a continuous distribution then using a Kruskal-Wallis one-way analysis of variance technique we can test the hypothesis that the average ratio of icebergs is not significantly different for gross visual shape classes. The result is that for the sample icebergs there is no significant difference. For summary purposes then the average of the averages 13.95 can be used as descriptive of the height draft ratio of icebergs regardless of visual shape class. Between the berg heights of 10 meters and 60 meters, which is the range of this sample, the height is related to the height to draft ratio by the power curve. Analysis of stereo pairs of twenty-two icebergs, in the region of Davis Straits, reveals that a reasonable estimate of total iceberg mass, in metric tons, can be arrived at by multiplying the gross dimensions of the iceberg height x width x length in meters together and then multiplying this product by a factor of 3.01. This factor accounts for the density difference between seawater and fresh water ice it also accounts for the average shape and mass distribution of icebergs.
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