The response of lead patterns in the Beaufort Sea to storm-scale wind forcing
| Autor: | Bernard A. Walter, James E. Overland |
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| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | Annals of Glaciology. 17:219-226 |
| ISSN: | 1727-5644 0260-3055 |
| DOI: | 10.3189/s0260305500012878 |
| Popis: | With the use of time series of AVHRR imagery we examine a non-typical case of ice motion and lead pattern formation in the Beaufort Sea during a period of persistent southwesterly to southerly winds during 31 March-14 April 1991. Our goal is to suggest sea-ice rheologies through the use of satellite imagery. Ice motions were estimated by making a negative of the first image in a time sequence and combining it with a second image using a logical AND operation. Thus leads for the first day are white and those for the second day are black. For the period 31 March-5 April with westerly winds there was a slip line oriented southwest-northeast across the central Beaufort Sea and another slip line parallel to it 150 km to the north. Relative motion was 0.015 m s−1 across the slip lines. With southerly winds during 9-14 April the entire field of leads was advected to the north. Lead patterns are organized on a hierarchy of scales and the scales are a result of the particular magnitude of forcing by the atmosphere. Angles between diamond-shaped lead features with spacings of both 150 km and 10-20 km are approximately 30°, which as Erlingsson showed corresponds to an angle of internal friction of 15°. We provide an argument for the scale-invariant nature of the lead patterns and suggest that it may be possible to parameterize small-scale (less than tens of km) lead patterns. |
| Databáze: | OpenAIRE |
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