Observations of Landfalling Wave Spectra during Hurricane Ike

Abstract

Observations of wave properties during Hurricane Ike are presented for eight temporary gauges in mean depths of 8.7–15.8 m over a 360-km section of coastline. These gauges cover both the strong (left) and weak (right) sides of the tropical cyclone, with one gauge immediately adjacent to landfall. Maximum significant wave heights are large over the entire section of the coast and reached 5.8 m near landfall but were at some locations significantly limited by the finite depths with significant wave height-to-depth ratios nearing 0.5 at landfall. Nondirectional spectral shapes changed sharply over the course of the storm, from strongly peaked profiles before landfall to much flatter, sometimes multipeaked, spectra as the hurricane came ashore. After landfall, the spectra on Ike’s strong side reverted to the sharply peaked form, whereas the weak side spectra were broader and often had multiple peaks. No waves during the storm appeared to be in equilibrium with local winds and water depths, although heights on the strong side of the storm were close.