POSTER Session 2

GLOBAL ZOOPLANKTON BIOMASS AND DIEL VERTICAL MIGRATION VIA EXTRAPOLATION OF THE PARTICLE SIZE DISTRIBUTION RETRIEVED FROM PASSIVE OCEAN COLOR OBSERVATIONS

The particle size distribution (PSD) is an important marine ecosystem, biogeochemistry and optics parameter. A recent novel PSD algorithm retrieves the parameters of an assumed power-law PSD (slope ranging from 2.5 to 6.0, and scaling parameter, No) using a 2-component, coated spheres, backscattering-based bio-optical model applied to mostly phytoplankton-sized particles and smaller. With significant assumptions, the PSD can be used to retrieve absolute and fractional size-partitioned phytoplankton carbon. Here, we extrapolate the PSD to larger particles to retrieve global mesozooplankton carbon biomass and diel vertical migration (DVM), as part of a NASA-funded project aiming to assess zooplankton contribution to vertical carbon transport, specifically via biogenic hydrodynamic transport (BHT). The project includes laboratory experiments and incorporating DVM in the ECCO-Darwin model; the latter will be informed by the satellite data presented here. We find that rescaling of the PSD slope (narrowing its range) and tuning of the No parameter are needed in order to achieve realistic biomass and DVM values globally, as compared with two data sets independent from the ocean color PSD: a lidar-based DVM retrieval, and the MAREDAT in-situ zooplankton biomass data set. We apply the novel algorithm to the latest OC-CCI v6.0 merged ocean color data set and present basic global spatio-temporal characteristics of the biomass and DVM retrievals globally. The implications of the need for the rescaling and tuning are discussed in the context of existing literature evidence that a power law PSD with a very conserved slope applies to marine ecosystems.

Tihomir Kostadinov, California State University San Marcos, USA, https://orcid.org/0000-0001-7628-2575

Darcy Taniguchi, California State University San Marcos, USA

Dustin Carroll, Moss Landing Marine Laboratories, USA

Eckart Meiburg, University of California Santa Barbara, USA

Monica Martinez Wilhelmus, Brown University, USA

Michael Behrenfeld, Oregon State University, USA

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