A new tool for model assessment in the frequency domain – Spectral Taylor Diagram : application to a global ocean general circulation model with tides

We introduce a new tool – the Spectral Taylor Diagram (STD) – for the comparison of time series in the frequency domain. The STD provides a novel way of displaying the squared-coherence, power, amplitude, phase, and root-mean-squared difference of discrete frequencies of two time-series. Each STD summarises these quantities in a single plot, for multiple targeted frequencies. The versatility of STDs is demonstrated through a series of sea-level comparisons between observations from tide gauges, and model results from a global eddy-permitting ocean general circulation model with explicit tidal forcing.