Experimental Port Kembla Directional Spectra
Directional Wave Spectral plots are being developed at MHL to display the rich directional energy data available from the OEH Waverider buoy network.
Going beyond the limited reporting usually provided (wave heights, period and direction), directional spectra plots show information about the sea state in an easy to interpret graphical medium, with an overview of the wave condition at a glance.
Analysis is generated hourly in line with the regular reporting of wave data available on this site.
The plots show the direction from which the waves propagating, so for NSW the wave energy will come from the top right (NE swell) to the bottom (S swell) of the plot. Long period waves are shown towards the centre of the plot, and short period waves down to 4sec are at the outer edges of the plot.
Sea states associated with high wind events can be seen as broad areas of colour in the edges of the plot as these events generate short period waves with wide directional spreading. Swell that is generated some distance from the buoy are usually small peaks in the plot near the centre as they are associated with long period waves from a narrow direction.
One of the key advantages of directional spectra plots are their ability to represent more than one wave event, where for example a southerly swell and a north-easterly sea can be seen in the one plot, but may be lost in simple wave parameters.
Analysis is performed on board the buoy using Fourier techniques, then processed and plotted at MHL. Alternative methods including Extended Maximum Entropy Method (Hashimoto et al. 1993) and Bayesian Direct Method (Hashimoto and Kobune 1987) are being investigated for improvements to the estimation results.
This is an experimental product, no guarantee is made or implied as to the accuracy or reliability of the information presented here.