Location of high frequency radio (HFR) instrument sites. All together, these sites are used to measure nearshore surface currents. They consist of a low-power transmitter sending radio waves and an antenna array, or receivers, that listen for the signal reflected back from the ocean. The return signal is Doppler-shifted by wave propagation (motion) and by surface currents, as well as wind direction and wave spectrum.
info:
http://www.satlab.hawaii.edu
https://cordc.ucsd.edu/projects/hfrnet/
Google Earth KML:
http://pacioos.org/kml/hfradio_stations.kmz