Evaluation of algorithms for wave height measurements with high frequency radar

Ocean wave conditions impact navigation, offshore operations, recreation, fisheries, safety of life at sea and hence the economic stability of any country´s maritime sector. Making accurate measurements of wave conditions will help validate wave models and will help with forecasts of the wave conditions over the next few days. The United States has put forth “A National Operational Wave Observation Plan” to meet this need. It has called for 133 wave measurements in the coastal zone. High Frequency radar systems that are already in place can be one type of sensor to fill this measurement gap. Seven 13 MHz HF radars collected wave data along the coast of New Jersey from February 1, 2012 to June 1, 2012. The measurements from the radars utilizing existing algorithms were compared with wave measurements from accelerometer measurements aboard National Buoy Data Center platforms. Since there were large distances between the comparison points we first determined what the correlation was amongst the various buoy platforms to gauge the variability within the region. This provided a baseline for the comparison between the HF radar measurements and the nearby buoy measurements. We then evaluated three new wave measurement algorithms at one of the radar stations to see if that improved the measurements. The correlation of the radar wave measurements with that of the buoy varied considerably. We then chose one radar station that had good correlation with the buoy measurement and tested new algorithms to extract the wave information from the radar spectra. In each case, the comparison between the in situ record with the new algorithm showed improvement. The measurement of wave information with the radar showed moderate correlation with the in situ measurements. The four algorithms each showed improvement over the existing one. HF radar could be a sensor to play a role in the US national waves plan.