DEFINING A MULTI-PARAMETER OPTICS-BASED APPROACH FOR ESTIMATING CHLOROPHYLL A CONCENTRATION USING OCEAN GLIDERS

Abstract

A bio-optical method for increasing the accuracy of chlorophyll a estimates from in situ fluorometers in the absence of traditional validation methods was implemented for autonomous gliders operating on the Scotian Shelf. The method generates a dynamic fluorescence-to-chlorophyll a conversion factor (F-factor) designed to account for bio-optical variability in the phytoplankton assemblage. Several changes were made to the method, allowing for the retention and analysis of depth-resolved information in the F-factor relationship. Trends in the F-factor with depth were driven by the bio-optical properties of the phytoplankton community, while horizontal trends were driven by the influence of coloured dissolved organic matter in the nearshore region of the study site. Variability in the F-factor within and between profiles introduced artifactual pattern into estimates of chlorophyll a, leading to a recommendation that the bio-optical method under investigation not be implemented for gliders on the Scotian Shelf.