Light penetration in the coastal waters off Goa

Abstract

Observations of light penetration have been carried out at 6 stations along the Goa Coast, India, for different periods during 1975-76, using a submarine photometer. Seasonal and spatial variations in the values of irradiance attenuation coefficient are evaluated and discussed. High values of attenuation coefficient observed immediately after SW monsoon appear to be due to turbid river discharges. High values of attenuation coefficient observed immediately after SW monsoon appear to be due to turbid river discharges. The waters are very clear by October/November. In January, the attenuation values are very high again, especially at the surface, in association with a phytoplankton bloom. Intermediate values of the attenuation coefficient have been observed from February to April, and by May, just before the onset of the SW monsoon rains, the waters are once again highly turbid, this time apparently due to churning action of wind-waves and strong currents. It has been found that the average irradiance attenuation coefficient (K sub(D)) from the surface to the Secchi depth, D, can be estimated from the relationship <i>K_D</i>(m^-1) = 0.11 + 1.28/<i>D</i>(m).