Signal sampling impacts on HF radar wave measurement

Averaging is required for the measurement of ocean surface wave spectra and parameters with any measurement system in order to reduce the variance in the estimates. Sampling theory for buoy measurements is well known. The same theory can be applied to the impact of sampling on the estimation of high-frequency (HF) radar power spectra from which wave measurements are derived. Some work on the impacts on the HF radar wave measurements themselves is reviewed and applied to datasets obtained with three different radar systems, operating at different radio frequencies in different geographical locations. Comparisons with collocated buoy measurements are presented showing qualitative agreement with the sampling impact predictions but indicating that there are more sources of differences than can be explained by sampling. Increased averaging is applied to two of these datasets to demonstrate the improvement in data quality and quantity that can be obtained.