SECCHI DISC OBSERVATIONS AND EXTINCTION COEFFICIENTS IN THE CENTRAL AND EASTERN NORTH PACIFIC OCEAN

Abstract

Measurements of submarine daylight were made with a photometer and Secchi disc and of water color with a Forel‐Ule color scale during three summer cruises in the central and eastern North Pacific Ocean. The relationships between extinction coefficients, reciprocals of Secchi disc readings, and color observations were determined and their applications and limitations are discussed. It is concluded that the disc is a useful tool, but that caution should be observed when extrapolating the relationship between Secchi disc measurements and extinction coefficients from one oceanic environment to another.