APPLICATION OF OVER-THE-HORIZON RADAR OBSERVATIONS TO SYNOPTIC AND MESOANALYSIS OVER THE ATLANTIC

Over-the-horizon (OTH) radar observations of surface wind direction of fer a high-resolution (15 km) resource for synoptic and mesoscale wind field analysis. With horizontal resolution at the lower end of the me soscale and areal coverage in the synoptic scale, OTH radar has the po tential to contribute significantly to the amelioration of the data sp arseness that has long plagued over-ocean surface analysis. Because of a twofold ambiguity in the OTH radar algorithm for determining surfac e wind direction, however, mapping surface wind directions unambiguous ly would normally require two radars with overlapping coverage. Altern atively, the single-radar ambiguity can be resolved by combining NWP m odel analyses and incidental surface wind observations with meteorolog ical insight. An approach to the latter, less expensive solution is pr esented that relies on the classic principles of streamline analysis a nd an easy-to-use graphical wind field editor developed specifically f or this task. A case study demonstrates the utility of the resulting O TH radar analyses of surface wind direction over the tropical Atlantic Ocean. Existing military OTH radars in several countries could be use d for such monitoring with little impact on their primary mission.