Author(s): W. D. Hibler; W. B. Tucker; W. F. Weeks
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Keywords: No Keywords
Abstract: This paper discusses recent work on the development of analysis procedures for obtaining drift and deformation measured from sequential visual imagery of sea ice that is located far from land. In particular for LANDSAT images far from land a semi-automatic procedure for transferring the location coordinates of a common set of ice features from the Earth coordinate system of one image to another is discussed. Necessary inputs for the transfer are the location coordinates (latitude and longitude) of the center of each image and the location of two arbitrary points on a known line of longitude; all this information is available from LANDSAT, although with some error. Errors in the transferral technique are examined using imagery over land and are found to be dominated by deviations (as large as 8 km) in the actual position of the center of the image from its stated position. The errors on average are, however, less than typical one-day drift distances. The LANDSAT image location errors also introduce uncertainties in the orientation of the coordinate systems after transfer. These errors will produce spurious apparent strains if velocities are estimated by simply taking position differences. This subtle effect may also occur if the coordinate system of a given floe is used as the common coordinate system. A least-squares strain program utilizing polar coordinates, which eliminates such spurious effects, is discussed.
Year: 1975