Colour, ultraviolet absorbance and salinity of the surface waters off the west coast of Ireland

Abstract

INTEREST in the relationship between the colour of seawater and various other surface properties of seawater has increased in anticipation of the launch of the Coastal Zone Colour Scanner, a multispectral instrument, aboard Nimbus-G satellite. During the late summer and autumn of 1977, at 73 hydrographic stations in Galway Bay and other waters along the west coast of Ireland (Fig. 1), measurements of water colour and of various chemical, biological and physical properties were obtained in accord with an expanded version of the ‘sea-truth’ protocol adopted for the ‘Ocean Colour Scanner’ experiment conducted earlier in the North Sea1. The strong correlations found between colour and surface salinity, and between colour and the concentration of dissolved organic matter, suggest that the images to be transmitted from this multispectral scanner will be useful in the identification and delineation of the runoff-influenced waters found along the west coast of Ireland.