The data archive for the phased array HF radars in the Australian Coastal Ocean Radar Network

The Australian Coastal Ocean Radar Network includes eight WERA phased array radar stations. The stations are configured in pairs in order to produce high quality gridded surface current data at 10-minute intervals at four sites. Other gridded parameters of significant wave height, dominant wave period, Bragg peak energies and directional wave spectral information are also extracted from the radar sea-echoes. Three of the sites operate at 8-9 MHz, giving ranges of up to 200 km for surface currents, while the fourth site operates in the 13-14 MHz band and has an operating range of 150 km. Each pair of radar stations operates on the same frequency and separation is achieved by an alternating sequence of 5 minutes on and 5 minutes off. First-Look analyses are carried out at the radar sites by proprietary WERA software and are transmitted by broadband phone connections to a base laboratory for operational monitoring and preparation for archiving. These data are attached to metadata in netCDF format and sent to the archive. Raw data (time series) are stored at the radar stations for each of the elements of the phased array receive antennas. At this stage the data have been sorted into range bins by the WERA firmware and a Radio Frequency Interference (RFI) reduction process is applied using a scan of the band by the radar receiver immediately prior to each 5-minute run. These time series data are returned to the laboratory on hard disks in a delayed mode every 2-3 months on a regular maintenance program. Delayed-mode re-processing is carried out using software developed by ACORN to achieve improved identification of Bragg peaks and subsequent improved parameter extraction. At this stage gridded data are combined from each pair of stations to produce hourly maps of surface current vectors and directional wave spectra. Quality flags are set for each data value before the delayed-mode data are filed for archiving.