Arctic-wide operational sea ice drift from enhanced-resolution QuikScat/SeaWinds scatterometry and its validation

The near-real-time enhanced-resolution QuikScat/SeaWinds (QS) scatterometry composite data are used for daily automatic 48-h sea ice tracking by maximum cross-correlation over the entire Arctic. A correlation window of 61 /spl times/ 61 pixels is used for best performance. Both QS polarizations, vertical (VV) and horizontal (HH), are used independently, which permits to filter the final results for erroneous vectors by comparing the two drift vectors, u/spl I.oarr//sub VV/ and u/spl I.oarr//sub HH/, respectively. Additional filtering is performed by setting a minimum correlation coefficient and by considering the spatial consistency of the motion field. The algorithm has been validated with winter 2002/2003 buoy data from the International Arctic Buoy Program showing error standard deviations in the 48-h displacement of 3.1 and 3.2 km in the latitude and longitude direction, respectively. This corresponds to an error standard deviation in ice drift speed of just 2.6 cm/s. Errors are largest in dynamic regions with lower ice concentrations as for example the southern Fram Strait. The enhanced-resolution data improve previous drift results by about 25%, but are still blurred by the necessary 36-h period to produce the composites.