Vertical structure of productivity and its vertical integration as derived from remotely sensed observations

Abstract

A method for predicting oceanic productivity from remotely sensed diffuse attenuation (488 nm) and surface chlorophyll concentration is presented. The method uses a climatological approach which consists of applying a set of regressions for each region and season to yield the depth of the chlorophyll maximum, the exponential slope of the chlorophyll profile, and the depths of various irradiance levels from the remotely sensed diffuse attenuation coefficient at 488 nm. These parameters, combined with the remotely sensed surface chlorophyll concentration and a model of quantum efficiency vs. irradiance, yield a vertical profile of productivity. This profile can be numerically integrated or directly integrated piecewise with a logarithmic approximation for the quantum efficiency model and a piecewise linear relationship of total irradiance and irradiance at 488 nm. The results favorably compare with productivity profiles calculated from direct measurements of chlorophyll and irradiance for a meridional transect of the North Pacific Ocean.