The bio‐optical state of ocean waters and remote sensing 1

TLDR

The diffuse attenuation coefficient K_T, a physical measure of ocean bio‑optical state, is readily measured at sea, correlates strongly with chlorophyll‑like pigment concentration C_K, can be sensed from space, and links to phytoplankton production theory. Pigment concentration and K_T quantify the fraction of light energy attenuated by phytoplankton. Analysis shows chlorophyll‑like pigments attenuate light at 0.016 ± 0.003 m⁻¹ (mg pigment m⁻³)⁻¹, C_K serves as a primary productivity index, and satellite‑derived bio‑optical measurements could enable rapid, repeated assessment of marine ecosystem parameters.

Abstract

The diffuse attenuation coefficient for irradiance, K T , is a physical measure of the bio‐optical state of ocean waters. From an analysis of irradiance, K T , and pigment concentration, the specific attenuation due to chlorophyll‐like pigments is found to be 0.016 ± 0.003 [m −1 (mg pigment m −3 ) −1 ]. The bio‐optical state of ocean waters can be remotely sensed by spacecraft sensors. K T is readily measured at sea and is highly correlated with and dependent on the chlorophyll‐like pigment concentration, C K . This pigment concentration and K T provide a measure of the fraction of radiant energy attenuated by phytoplankton. This fraction, in turn, is closely related to the production equations formulated by Bannister and can be directly incorporated into a general theory of phytoplankton dynamics. C K may also be used as an index of primary productivity. The determination of the bio‐optical state of ocean waters by surface vessel provides direct information concerning the productivity of these waters; to the extent that the bio‐optical state can be determined by satellite, it may be possible to examine important parameters of the marine ecosystem rapidly and repeatedly.