Wind direction alias removal studies of Seasat scatterometer-derived wind fields

Owing to the antenna configuration, and the biharmonic nature of the anisotropic return of the probing radar, the SEASAT scatterometer wind reports consist of as many as four wind directions at each point of observation. A systematic methodology is proposed for selection of the true direction from among these, in the absence of any in situ observations. The techniques employed are those familiar to meteorological analysts. They were subjected to rigorous testing for the JASIN workshop, with two teams performing independent analyses. The agreement of the two analyses was striking. Comparison with wind directions from the JASIN data set, and those estimated from the analyzed pressure field, show agreement largely within the SEASAT specifications. It is concluded that the methodology employed is suitable for SEASAT scatterometer data users.