Bio-optical properties of Antarctic Peninsula waters: differentiation from temperate ocean models

Abstract

An extensive biological and optical data set was collected during a 4 month cruise as part of the Research on Antarctic Coastal Ecosystem Rates (RACER) program conducted in coastal waters of the Antarctic Peninsula and adjacent open ocean waters of Drake Passage. Chlorophyll plus phaeopigment (Chl + Phaeo) concentration in the upper mixed layer ranged 2 orders of magnitude from 0.5 to 50 mg Chl + Phaeo m −3 during the study. The large variations in pigment corresponds to variations in the beam attenuation coefficient at 660 nm ( c t ranging from 0.5 to >2.5 m −1 and in the diffuse attenuation coefficient ( k d) for 441 nm ranging from 0.04 to >1.0 m −1. Chl + Phaeo specific particulate beam attenuation and spectral absorption coefficients suggest that detrital contributions are relatively low and that pigment package effects are relatively important compared to low latitude observations. The combination of these effects causes low pigment specific absorption and scattering. This regional differentiation in particulate optical properties has a significant effect on models of the relationship between Chl + Phaeo and spectral values of k d and upwelled radiance ( L u). Implications of these effects for modeling light propagation through the water column and for remote sensing of phytoplankton pigments are discussed.