Comparison of the Met Office Global Spectral Wave Model with Envisat Satellite and Buoy Observations

The Met Office routinely runs a global spectral wave model providing analyses and forecasts of sea state on a grid spacing of approximately 60 km. The modelled two-dimensional wave energy spectra are compared with the Advanced Synthetic Aperture Radar (ASAR) Envisat satellite observations on a daily basis. Comparisons are also made with frequency ocean wave energy spectra observed by a moored buoy near Christmas Island (0.02S 153.87W) and with the wave height observed by the radar altimeter RA2 onboard the same satellite Envisat as the ASAR instrument. Comparison results indicate that Envisat ASAR level 2 energy spectra are systematically higher than the modelled spectra in the long periods (>16 s) or low frequency parts. There is a better agreement in the mid-periods of about 8 16 s for the integrated 1-D spectra. The variation of ASAR wave energy spectra is much larger than that of the modelled spectra. Comparison of the wave model and buoy 1-D wave spectra shows that the model spectra are in much better agreement with the buoy wave spectra than with the ASAR spectra. It also revealed that both the buoy and model spectra have similar variability while the ASAR spectra variations are much larger than them. The integrated model significant wave heights are also in good agreement with the along track RA2 altimeter data.