An operational model for separating the absorption of optically active constituents from SeaWiFS measurements

Abstract

ABSTRACT To analytically or semi-analytically convert satellite-measured remote sensing reflectance (R rs) to widely used biogeochemical variables from the global oceans, it is common to first determine the total absorption coefficient from satellite R rs data and then separate the total absorption coefficient into the absorption coefficients of phytoplankton (a ph ) and non-phytoplankton (a dg ) pigments. While still considering the spectral characteristics of a ph and a dg , we developed an operational model to improve the accuracy of estimating a ph and a dg products from satellite R rs data. Our results show that our model effectively separates a ph and a dg from the total absorption coefficient spectrum, which decreases the uncertainty by 6.81% to 17.52% compared to a widely used quasi-analytical algorithm. Moreover, after applying the new model to SeaWiFS satellite images, we present the spatial and temporal variations of a ph (443) and a dg (443) for the global oceans from 1997 to 2010, further confirming that coastal zones exhibited higher a ph (443) and a dg (443) than the open oceans during that time. In addition, a ph (443) and a dg (443) declined in the tropical Indian Ocean Gyre over those 13 years. Our results improve our knowledge of the spatiotemporal variations of optical properties of the global oceans, and also demonstrate the potential of our model in separating the total absorption.