Skew Surge

A skew surge is the difference between the maximum observed water level and the maximum predicted tidal level regardless of their timing during the tidal cycle. There is one skew surge value per tidal cycle. The advantage of using skew surge is that it contains the true meteorological contribution to the surge, whereas the non-tidal residual (i.e. the measured water level minus the astronomical tide) contains the meteorological contribution, in addition to harmonic prediction errors or timing errors and non-linear interactions, which can artificially bias the surge.

 

 Figure: Skew surge – the difference between the maximum observed water level and the maximum predicted tidal level regardless of their timing during the tidal cycle.