Estimation of large-scale sea-ice motion from SSM/I 85.5 GHz imagery

Abstract

This paper describes the application of an automated cross-correlation technique to pairs of 85.5 GHz Special Sensor Microwave Imager (SSM/I) images to obtain ice motion over the entire Arctic Basin for a contiguous two month period between December 1993 and January 1994. Although the surface ice information in the imagery is coarse and noisy, the area cross-correlation method is quite successful in picking up ice-motion information. The accuracy of 85.5 GHz SSM/I derived ice motions is evaluated by comparing results with Arctic buoy drift. Over 390 comparisons with buoy-drift estimates of ice displacement were made with an overall correlation of 0.75 and an average vector magnitude error in ice velocity of 3.5 km d−1. The main difficulty with the automated technique is the tendency to overestimate ice displacement compared to buoy data by about 14%. Two detailed examples of ice motion are presented. The first occurred in December 1993, when a major westward shift in the ice pack took place in the Canada Basin and opened up a very large lead off Banks and Prince Patrick Islands. The second example occurred in January 1994, when an intense anticyclone over the Canada Basin produced a strong Beaufort Gyre.