Mapping surface currents near the Gulf Stream using the Air Force over-the-horizon-radar

During nine days in 1993 and 1994, the authors pointed the Air Force OTH-B radar in Maine southward to illuminate a 240,000 km/sup 2/ ocean area off the Carolina coast to test the feasibility of mapping radial surface currents. In the past, ionospheric motions have masked the effects of ocean currents on the OTH sea echo spectrum. The present authors average the radar measurements over time to take advantage of the shorter time scales of ionospheric variability, compared with those of ocean currents. In addition, they have concentrated on the times of day when the reflecting layer is most stable. Examples of daily current maps show features of the Gulf Stream core and associated eddies with reasonable day-to-day consistency. Agreement is good with the location of SST features on infrared (AVHRR) imagery and with acoustic-Doppler current profile measurements on board research vessels.