Tracking and Monitoring Hurricanes by HF Skywave Radar over the Gulf of Mexico.

This report describes the results of a study to evaluate the effectiveness of a high-frequency skywave radar used to determine the track, movement, size, and intensity of hurricanes from ocean gravity waves. Experimental data were collected using the Wide Aperture Research Facility WARF, a high-resolution skywave radar capable of forming a 12 deg. beam at 15 MHz, located in central California. The data were collected for hurricanees Anita, Babe, Caroline, and Eloise in the Gulf of Mexico, and Hurricane Kate in the Pacific Ocean. One or more position estimates were made from radar-derived surface wind direction maps covering a 2 deg. of latitude radius for each hurricane, and agreement to within 10 to 40 km of the National Hurricane Center Best Tracks was found. Both day and night measurements were made, as well as one- and two-ionospheric-hop measurements extending out to ranges of 2800 to 4000 km. The first WARF-measured track was generated for hurricane Anita from 20 independent position estimates over a 5-day period. WARF measurements of the ocean wave spectrum and surface currents were made during hurricanes Anita and Babe. A parametric wave model developed elsewhere was used to compute wind speeds. Preliminary WARF wind-speed measurements show agreement to within 1 to 2 ms when compared with winds measured by aircraft and at several offshore oil platforms. Author