A Statistical Analysis of Storm Surges in Torres Strait

Abstract

Tidal harmonic constituents were obtained from analysis of one year of simultaneous sea level observations at each of six stations in Torres Strait and the subsequent tidal residuals were computed. Examination of the residuals showed that Frederick Point and Twin Island have similar responses to meteorological effects; likewise Booby Island, Goods Island and Turtle Head have common characteristics. It was found that the east-west component of surface winds is mainly responsible for the generation and propagation of surges, and winds of velocity less than 12 m/s are insignificant in the generation of surges. Winds from the west develop positive surges west of Ince Point and negative surges east of Ince Point. The reverse is true for winds from the east. A regression technique was used to develop a system for forecasting surges using meteorological data available from nearby meteorological stations. Variations in mean sea level with periods of 3-4 days were observed. These oscillations were not simply related to any local meteorological effects and are considered to have their origin either in the Indian Ocean or in the Coral Sea. It is suggested that a mechanism exists whereby surges generated outside Torres Strait may affect surge levels within the Strait.