Measurement of inherent optical properties in the Arabian Sea

Inherent optieal properties, absorption and beam attenuation were measured in-situ using a reflective tube absorption meter at nine wavelengths, 412, 440, 488, 510, 555, 630, 650, 676 and 715 nm, in the Arabian Sea during Mar ch. Since inherent optical properties depend on the constituents of the wat er, these data were analysed with the pigment concentration and total suspe nded matter. The results are compared with those of other investigators usi ng in-vivo methods. A non-linear relationship with Secchi depth was used to evaluate beam attenuation at 510 nm. Results of linear regression of beam attenuation at 490 nm with that at other wavelengths were found to be compa rable with those reported by others for wavelength above 440 nm. Though the slope of regression increased from 715 to 440 nm a deviation with a decrea se in the slope was noticed at 412 nm.