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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, C10011, doi:10.1029/2006JC003706, 2007

Seasonal rhythms of net primary production and particulate organic carbon flux to depth describe the efficiency of biological pump in the global ocean

Michael J. Lutz

Department of Geological and Environmental Sciences, Stanford University, Stanford, California, USA


Ken Caldeira

Department of Global Ecology, Carnegie Institution of Washington, Stanford, California, USA


Robert B. Dunbar

Department of Geological and Environmental Sciences, Stanford University, Stanford, California, USA


Michael J. Behrenfeld

Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA


Abstract

We investigate the functioning of the ocean’s biological pump by analyzing the vertical transfer efficiency of particulate organic carbon (POC). Data evaluated include globally distributed time series of sediment trap POC flux, and remotely sensed estimates of net primary production (NPP) and sea surface temperature (SST). Mathematical techniques are developed to compare these temporally discordant time series using NPP and POC flux climatologies. The seasonal variation of NPP is mapped and shows regional- and basin-scale biogeographic patterns reflecting solar, climatic, and oceanographic controls. Patterns of flux are similar, with more high-frequency variability and a subtropical-subpolar pattern of maximum flux delayed by about 5 days per degree latitude increase, coherent across multiple sediment trap time series. Seasonal production-to-flux analyses indicate during intervals of bloom production, the sinking fraction of NPP is typically half that of other seasons. This globally synchronous pattern may result from seasonally varying biodegradability or multiseasonal retention of POC. The relationship between NPP variability and flux variability reverses with latitude, and may reflect dominance by the large-amplitude seasonal NPP signal at higher latitudes. We construct algorithms describing labile and refractory flux components as a function of remotely sensed NPP rates, NPP variability, and SST, which predict POC flux with accuracies greater than equations typically employed by global climate models. Globally mapped predictions of POC export, flux to depth, and sedimentation are supplied. Results indicate improved ocean carbon cycle forecasts may be obtained by combining satellite-based observations and more mechanistic representations taking into account factors such as mineral ballasting and ecosystem structure.

Received 10 June 2005; accepted 2 February 2007; published 10 October 2007.

Keywords: Biological pump; net primary production; carbon flux; seasonality; export; remineralization; sediment traps; p ratio; remote sensing.

Index Terms: 4805 Oceanography: Biological and Chemical: Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912); 4815 Oceanography: Biological and Chemical: Ecosystems, structure, dynamics, and modeling (0439); 4806 Oceanography: Biological and Chemical: Carbon cycling (0428); 4845 Oceanography: Biological and Chemical: Nutrients and nutrient cycling (0470, 1050); 4863 Oceanography: Biological and Chemical: Sedimentation (1861).

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Citation: Lutz, M. J., K. Caldeira, R. B. Dunbar, and M. J. Behrenfeld (2007), Seasonal rhythms of net primary production and particulate organic carbon flux to depth describe the efficiency of biological pump in the global ocean, J. Geophys. Res., 112, C10011, doi:10.1029/2006JC003706.