%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Whitt, D. B.
%A Levy, Marina
%A Taylor, J. R.
%T Low-frequency and high-frequency oscillatory winds synergistically enhance nutrient entrainment and phytoplankton at fronts
%D 2017
%L fdi:010069462
%G ENG
%J Journal of Geophysical Research : Oceans
%@ 2169-9275
%M ISI:000398063100015
%N 2
%P 1016-1041
%R 10.1002/2016jc012400
%U https://www.documentation.ird.fr/hor/fdi:010069462
%> https://www.documentation.ird.fr/intranet/publi/2017/04/010069462.pdf
%V 122
%W Horizon (IRD)
%X When phytoplankton growth is limited by low nutrient concentrations, full-depth-integrated phytoplankton biomass increases in response to intermittent mixing events that bring nutrient-rich waters into the sunlit surface layer. Here it is shown how oscillatory winds can induce intermittent nutrient entrainment events and thereby sustain more phytoplankton at fronts in nutrient-limited oceans. Low-frequency (i. e., synoptic to planetary scale) along-front wind drives oscillatory cross-front Ekman transport, which induces intermittent deeper mixing layers on the less dense side of fronts. High-frequency wind with variance near the Coriolis frequency resonantly excites inertial oscillations, which also induce deeper mixing layers on the less dense side of fronts. Moreover, we show that low-frequency and high-frequency winds have a synergistic effect and larger impact on the deepest mixing layers, nutrient entrainment, and phytoplankton growth on the less dense side of fronts than either high-frequency winds or low-frequency winds acting alone. These theoretical results are supported by two-dimensional numerical simulations of fronts in an idealized nutrient-limited open-ocean region forced by low-frequency and high-frequency along-front winds. In these model experiments, higher-amplitude low-frequency wind strongly modulates and enhances the impact of the lower-amplitude high-frequency wind on phytoplankton at a front. Moreover, sensitivity studies emphasize that the synergistic phytoplankton response to low-frequency and highfrequency wind relies on the high-frequency wind just below the Coriolis frequency.
%$ 036 ; 032 ; 020