Particulate organic carbon in the surface waters of the North Atlantic: spatial and temporal variability based on satellite ocean colour

Abstract

We have examined the 16-year time series of particulate organic carbon (POC) concentration in the surface waters of the North Atlantic derived from SeaWiFS and MODIS-Aqua data. The annual mean POC concentrations are the highest in the northern North Atlantic, reaching 120 mg m⁻³. Moving south, the mean annual POC concentrations decrease to minimum values of about 30 mg m⁻³ at around 30° N and increase in the equatorial region to about 70 mg m⁻³. The seasonal amplitude of POC concentration in the northern North Atlantic region is larger when compared to other regions. The annual mean surface POC concentrations in the entire North Atlantic basin show a statistically significant trend with an average decrease of 0.79 mg m⁻³ year⁻¹. Regionally averaged 16-year mean POC biomass integrated over the optical depth, euphotic depth, and mixed-layer depth is estimated at about 1.27, 4.34, and 4.59 g m⁻², respectively. Even larger biomass of 6.26 g m⁻² is estimated if one chooses to use in the calculations the greatest from the daily values of the estimates listed above at each pixel of the satellite data. Comparisons of POC biomass with primary productivity allowed us to assess temporal and spatial patterns of POC losses.

Acknowledgements

The author would like to thank all the people who were involved in the programmes providing free access to the data sets used in this study. The ocean colour data were made available through the NASA OceanColor Web (oceancolor.gsfc.nasa.gov/). Primary productivity and Mixed Layer Depth data were provided by the Ocean Productivity Web at the Oregon State University (www.science.oregonstate.edu/ocean.productivity/). US JGOFS data were supplied through US JGOFS Synthesis & Modeling Project (www1.whoi.edu/mzweb/syndata.html).

Funding

This work was supported by the National Science Centre (NCN) in Poland [grant number 2011/01/M/ST10/07728] “Global estimates of particulate organic carbon reservoir and export flux in the ocean based on satellite ocean colour data”.