Carbon Flux in the Subtropical North Atlantic

The subtropical gyres are the largest coherent biomes of the global oceans, circular water masses located in the subtropical latitudes of each major ocean basin, and bounded by several ocean currents. These anticyclonic gyres are known as open ocean deserts because of the paucity of nutrients and phytoplankton biomass and can be recognized in satellite images of ocean color (see image above) as blue regions.

Because of their vast area (about 50% of the global ocean), subtropical gyres are important in the global carbon cycle. We are investigating carbon export from the subtropical North Atlantic gyre in a comparative fashion at two time series stations, one located in the eastern subtropical gyre north of the Canary Islands (ESTOC, European Station for Time-Series in the Ocean, Canary Islands) and in the western subtropical Atlantic south of Bermuda (BATS, Bermuda Atlantic Time-Series station), a US JGOFS station. Despite their similar look at the surface, we have found that there are differences in the supply of new nutrients to the surface which ultimately determine the removal efficiency of primary production to the deep sea. In this former NASA funded research project we combined the analysis of water column and particle trap measurements at the time series stations ESTOC and BATS with satellite remote sensing to link open ocean productivity with the export of carbon and associated elements to the deep ocean. See references below for results stemming from this project.

References:

P. Helmke, S. Neuer, M. Conte, M. Lomas, and T. Freudenthal. 2010. Cross-basin variability of organic carbon export and flux attenuation in the subtropical North Atlantic Gyre. Deep-Sea Research I 57, 213-227.

Cianca A., P. Helmke, B. Mouriño, M-J. Rueda, O. Llinás, and S. Neuer. 2007. Decadal analysis of hydrography and in situ nutrient budgets in the western and eastern North Atlantic subtropical gyre, Journal of Geophysical Research, 112. C07025, doi:10.1029/2006JC003788.

Neuer, S., A. Cianca, P. Helmke, T. Freudenthal, R. Davenport, M. Knoll, M. Santana-Casiano, M. González-Davila, M. Rueda and O. Llinás. 2007. Biogeochemistry and hydrography in the Eastern Subtropical North Atlantic gyre. Results from European Time-Series Station ESTOC. Progress in Oceanography 72, 1-29.

Neuer, S., M.E. Torres-Padròn, M.D. Gelado-Caballero, J. Hernandez-Brito, M.J. Rueda and Gerold Wefer. 2004. Dust deposition pulses to the eastern subtropical North Atlantic gyre: Does ocean’s biogeochemistry respond? Global Biogeochemical Cycles, 18, GB4020, doi: 10.1029/2004GB002228.