INTERANNUAL VARIABILITY IN IRISH SEA TURBIDITY AND RELATION TO WIND STRENGTH

An existing method for estimating the turbidity of the Irish Sea has been used to estimate the mean annual water clarity in the Irish Sea from 1987–97. The method is based on a strong relationship found between the satellite-measured reflectance of light in the orange–red portion of the visible spectrum and water clarity parameters such as Secchi depth (Zd). Analysis of satellite reflectance imagery indicated there was interannual variability in the water turbidity within the Irish Sea as a whole, but no overall trend between 1987–97 has been established. In general, trends at any one location follow the overall pattern, although for the years 1988–90 there is interregional variability. The year-to-year variability in turbidity, however, has been positively correlated with changes in the mean annual regional wind strength and the storm index across the Irish Sea. The results provide evidence for the large-scale control of turbidity processes in coastal seas by the mean prevailing meteorological conditions.