Validation of chlorophyll fluorescence derived from MERIS on the west coast of Canada

Abstract

MERIS on Envisat provides images of above‐atmosphere spectral radiance in 15 bands of the baseline spectral band‐set. This set includes three bands centered at 665, 681 and 709 nm, placed to measure the fluorescence emission from chlorophyll a in marine and fresh water phytoplankton at 685 nm, stimulated by ambient sun and sky light. We compare the observed fluorescence signal levels with measurements of extracted chlorophyll from research cruises and buoy data during 2002 and 2003, and with satellite estimates of chlorophyll from the blue to green ratio observed by MERIS. We present an average relation between fluorescence and surface chlorophyll concentration based on a simple model accounting for absorption of stimulating and emitted radiation by chlorophyll pigments, which gives a first‐order fit to the observations.