Sea-Truthing A Satellite Technique For Ocean Surface Flow Estimation

Abstract

Feature tracking is a technique that produces a sea surface velocity field from sequential images of sea surface brightness temperature derived from satellite measurements of upwelling radiation intensity. To test the validity of the vector fields produced by feature tracking, the trajectories of model water parcels moved by the vector field are compared with the trajectories of actual drifting buoys. Six buoys in the Gulf of Mexico during the spring of 1989 serve as the basis for the comparison. Using feature tracking on two different image pairs pairs I estimated two velocity vector fields. then developed and used a fourth-order Runge-Kutta integration routine to move model water parcels through the field, using derivatives supplied by bivariate interpolation directly from the velocity field. The correlation between parcel and buoy tracks is fairly good over the first 24 hours, although the results show wide variability and indicate a direction for improvement. Increased proficiency in feature tracking, advancement to time-dependent fields, and improved interpolation methods would allow vector fields derived by feature tracking to more closely mirror kilometer scale sea surface motion.