Large to submesoscale surface circulation and its implications on biogeochemical/biological horizontal distributions during the OUTPACE cruise (SouthWest Pacific)

Type Article
Date 2018-04
Language English
Author(s) Rousselet Louise1, de Verneil Alain1, Doglioli Andrea M.1, Petrenko Anne A.1, Duhamel SolangeORCID2, Maes Christophe3, Blanke Bruno3
Affiliation(s) 1 : Aix Marseille Univ, Univ Toulon, CNRS, IRD,OSU PYTHEAS,MIO,UM 110, F-13288 Marseille 09, France.
2 : Lamont Doherty Earth Observ, Div Biol & Paleo Environm, POB 1000,61 Route 9W, Palisades, NY 10964 USA.
3 : UBO, IFREMER, CNRS, IRD,LOPS, F-29280 Brest, France.
Source Biogeosciences (1726-4170) (Copernicus Gesellschaft Mbh), 2018-04 , Vol. 15 , N. 8 , P. 2411-2431
DOI 10.5194/bg-15-2411-2018
WOS© Times Cited 11
Note Special issue Interactions between planktonic organisms and biogeochemical cycles across trophic and N2 fixation gradients in the western tropical South Pacific Ocean: a multidisciplinary approach (OUTPACE experiment) Editor(s): T. Moutin, S. Bonnet, K. Richards, D. G. Capone, E. Marañón, and L. Mémery

The patterns of the large-scale, meso- and submesoscale surface circulation on biogeochemical and biological distributions are examined in the Western Tropical South Pacific (WTSP) in the context of the OUTPACE cruise (Feb–April 2015). Multi-disciplinary original in situ observations were achieved along a zonal transect through the WTSP and their analysis was coupled with satellite data. The use of Lagrangian diagnostics allows for the identification of water mass pathways, mesoscale structures, and submesoscale features such as fronts. In particular, we confirmed the existence of a global wind-driven southward circulation of surface waters in the entire WTSP, using a new high-resolution altimetry-derived product, validated by in situ drifters, that includes cyclogeostrophy and Ekman components with geostrophy. Two subregions show counter-intuitive water mass trajectories due to mesoscale circulation: i) the Coral Sea with surface exchanges between the North Vanuatu Jet and the North Caledonian Jet; and ii) the zonal band between 180° W and 170° W with an eastward propagation whereas a westward general direction dominates. Fronts and small-scale features, detected with Finite-Size Lyapunov Exponents (FSLE), are correlated with 25 % of surface tracer gradients which reveals the significance of such structures in the generation of submesoscale surface gradients. Additionally, two high-frequency sampling transects of biogeochemical parameters and micro-organism abundances demonstrate the influence of fronts in controlling the spatial distribution of bacteria and phytoplankton, and as a consequence the microbial community structure. All circulation scales play an important role that has to be taken into account when analysing the data from OUTPACE but also, more generally, to understand the global distribution of biogeochemical components.

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Rousselet Louise, de Verneil Alain, Doglioli Andrea M., Petrenko Anne A., Duhamel Solange, Maes Christophe, Blanke Bruno (2018). Large to submesoscale surface circulation and its implications on biogeochemical/biological horizontal distributions during the OUTPACE cruise (SouthWest Pacific). Biogeosciences, 15(8), 2411-2431. Publisher's official version : , Open Access version :