The case for building a current-mapping over-the-horizon radar

Results of recent NOAA tests with the U.S. Air Force and U.S. Navy over-the-horizon (OTH) radars show that it is possible to map near-surface currents with 10-15-km resolution to ranges greater than 2,500 km. The technique is similar to that used by commercially available high-frequency current-mapping radars, except that range is greatly extended by bouncing the radar beam off the ionosphere. Current maps made with U.S. Navy OTH radars often show new detail never before seen, for example, the complex space-time structure of the Florida Current, as well as large currents driven ahead of an Atlantic hurricane. However, the military taskloads of these radars preclude their operational use for continuous, large-area ocean monitoring. For that purpose, a dedicated low-cost radar system would be required. A possible installation would cover the Gulf of Mexico, the Caribbean Sea, and the hurricane approaches to the U.S. East Coast and Gulf Coast. The authors examine the costs, benefits, problems, and potential customers of such a radar.