High Frequency radar measurement resiliency with bistatics

Increasing the resiliency of High Frequency radar measurements has been a priority within the community for the past several years. One method to increase resiliency is through the use of a bistatic radar configuration, which is unique to the SeaSonde HF radar. This is achieved by separating the transmit and receive stations and then linking them through the Global Positioning System (GPS) reference time signal. A study was undertaken to determine the impact of bistatic data on the surface current measurements of the Mid Atlantic Bight. Simulation software was used to model different permutations of transmit and receive stations to determine if there was an optimal configuration. The software modeled the Geometric Dilution of Statistical Accuracy (GDOSA) of the HF radar coverage area. GDOSA describes regions where combination from radials to totals is of high accuracy because the crossing angle between measurements from two different radars is orthogonal. The converse to this are regions where the total vector measurement are of low accuracy because the measurements from two different radars are nearly parallel. The scenarios tested included the bistatic measurements from the adjacent two, three and four stations on either side of a receive station. The simulation was applied to the 5, 13 and 25 MHz networks that are operated as part of the Mid Atlantic Regional Association Coastal Ocean Observing System (MARACOOS). We also simulated radars being offline to determine if any were more critical than others. Initial findings indicate that the area of highest data quality can be increased by a factor of five when the network is fully bistatic. The use of three or four adjacent radars did not increase the coverage compared to the adjacent two radars. The results of the site outage tests indicated that the loss of certain sites could reduce the coverage of the network by as much as 55%. The results found here have implications for the approximately 300 High Frequency radars that are in operation around the globe. With the addition of a hardware and software to make the network bistatic the coverage area with the highest accuracy can be increased by a dramatic amount.