The relationship between beam attenuation and chlorophyll concentration and reflectance in Antarctic waters

Optical and biological data collected during the two-month R.R.S Discovery expedition in Antarctic waters in the Austral spring were used to examine the relationships between c (660 nm), chlorophyll a and the reflectance ratios R(443)R(550), R(490)IR(550) R(443 nm). Values of (c-cw)(660 nm) varied from 0.20 to 1.2 m −1 being generally positively correlated with the chlorophyll concentration. The computed values of the pigment specific beam attenuation coefficient c* were greater than those typical in Case I waters, exceeding 0.9 m2 mg−1, reducing the accuracy of the chlorophyll remote sensing algorithms designed for Case I waters. The covariance of phytoplankton and related pigments with beam attenuation was examined by the regression equation c - cw = A + B (Chl a + phaeo), and the residuals were used to identify the non-chlorophyll dependent data in the region. When the non-chlorophyll dependent data were removed, the accuracy of the chlorophyll remote sensing model was significantly improved.