Evaluation of fluorometrically-derived chlorophyll a as a satellite ocean color validation product using statistical metrics

Abstract

The fluorescence of chlorophyll a (Chl a ) has long been considered a reliable estimate of phytoplankton biomass in aquatic environments. The in vitro fluorometric method for measuring Chl a is a simple, fast, and cost-effective way to estimate phytoplankton biomass. High performance liquid chromatography measurements (HPLC) of Chl a (HChl a ) have been used historically for ocean color validation. The applicability of fluorometrically-derived Chl a (FChl a ) to satellite ocean color validation has not been fully evaluated. To this end, we developed statistical metrics to evaluate the uncertainty of fluorometric measurements of Chl a by comparing them to coincident measurements made by HPLC. The distribution of uncertainties demonstrates occasional trends in the discrepancies between FChl a and HChl a , from which we developed a set of recommendations for future collection and validation efforts.