Estimation of some characteristics of ocean waters using optical data (Case I)

The connection between the optical characteristics of the sea water measured by remote and in-situ methods and the concentration of specific elements may be formulated as an inverse problem. The authors present a new algorithm for estimation of water quality parameters such as chlorophyll pigment concentration (Cchl), absorption of “yellow substance” (“y.s”) (a_y(390)), absorption of detritus (a_d(400)), and volume concentration of small and large particles, (Vsp and Vlp) from the spectral diffuse attenuation coefficient Kd(λ) and other optical data. The inverse problem was solved by non-linear programming methods with adaptive strategy. Optical data were collected at bio-optical stations of P16 WOCE expedition going along 152° W longitude from south to north using a profiling spectroradiometer. MER-2040 which measures spectral downwelling irradiance Ed(z,λ) and upwelling radiance Lu(z,λ) (for wavelengths 410, 441, 488, 520, 565, 665 nm) as well as beam attenuation c(z,660 nm), and fluorescence Fl(z). Chlorophyll concentration values, measured in the surface layer and at fluorescence maximum as well as water type classification based on Kd(490) values allow to say that water belongs to Jerlov´s water types (JWT) from IA to II which correspond to Case I, with phytoplankton predomination which is typical to open ocean