In:
Biogeosciences, Copernicus GmbH, Vol. 15, No. 8 ( 2018-04-20), p. 2411-2431
Abstract:
Abstract. 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
(February–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. The mesoscale activity is shown to be responsible for
counter-intuitive water mass trajectories in two subregions: (i) the Coral
Sea, with surface exchanges between the North Vanuatu Jet and the North
Caledonian Jet, and (ii) around 170∘ W, with an eastward pathway,
whereas a westward general direction dominates. Fronts and small-scale
features, detected with finite-size Lyapunov exponents (FSLEs), 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 microorganism 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 not only when analysing the data
from OUTPACE but also, more generally, for understanding the global distribution
of biogeochemical components.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-15-2411-2018
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2158181-2
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