A 30-MHz ground-wave ocean surface radar has been deployed inside the Great Barrier Reef where the water is sheltered from ocean swell. The spatial resolution of the radar is 3 km radially and 3.5� in azimuth. In each cell a 102.4-s time series is used to determine radial surface currents, wind directions, root- mean-square wave heights and wind speeds. Coincident observations of sea-wave spectra, surface currents and boundary-layer winds are used to evaluate the radar performance and to modify some of the methods of data analysis to suit these conditions. Surface current values are observed by the radar to an accuracy of �0.05 m s-1, wind directions to �10� , root-mean-square wave heights to 0.15 m and wind speeds to �3 m s-1. In some spectra, the peak in the second-order continuum caused by the non-directional sea- wave spectrum is not resolved from a second-order resonance line. This disallows the derivation of the period of the dominant sea wave on a routine basis.
The 12 MHz VNG standard frequency transmitted from Lyndhurst has been phase compared with a local standard at Townsville over a total of 54 days. The Doppler shift introduced by the one ionospheric reflection has a diurnal trend which is predictable from the ionosphere parameters fo F2 and M3000F. The optimum time of day for frequency dissemination using VNG 12 is between 1100 and 1530 h. Faster fluctuations generally obscure the diurnal trend, however, and an accuracy of � 0�1 Hz on the 12 MHz carrier is attainable only by averaging the incoming frequency over a 1 h period. Spectral analysis of the fluctuations in frequency show significant spectral amplitudes down to short periods of about 1 min where the time resolution of the measurements provides a cutoff.
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