Contents lists available at ScienceDirect Dynamics of Atmospheres and Oceans journal homepage: www.elsevier.com/locate/dynatmoce NPZ response to eddy-induced upwelling in a Brazil Current ring: A theoretical approach Filipe Pereira a, ⁎ , Ilson C.A. da Silveira a , Glenn R. Flierl b , Amit Tandon c,d a Departamento de Oceanografia Física, Química e Geológica, Instituto Oceanográfico, Universidade de São Paulo, São Paulo, SP 05508, Brazil b Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, United States c Mechanical Engineering Department, University of Massachusetts Dartmouth, Dartmouth, MA 02747, United States d School for Marine Science & Technology, University of Massachusetts Dartmouth, New Bedford MA, 02744, United States ARTICLE INFO Keywords: Brazil Current Contour dynamics Cyclonic meander Mesoscale process NPZ model Upper ocean ABSTRACT This work explores the efect of a cyclonic mesoscale feature of the Brazil Current (BC) moving northward of SE Brazil (20° S–23° S) in the Nutrients-Phytoplankton-Zooplankton (NPZ) dy- namics. We employ the contour dynamics technique in a quasi-geostrophic, inviscid, 1½-layer model set as a meridional jet fowing southward along a rigid western boundary. This hydro- dynamical model is coupled to a conventional NPZ model. We evaluate two distinct scenarios: (1) Plankton in a mixed layer (ML) with time-variable depth and no entrainment and; (2) Plankton in an ML held at a fxed depth, which allows entrainment. We perform simulations with diferent ML depths representing summer (42 m) and winter (86 m) for the region of interest. The presence of the western boundary allows the cyclonic ring to propagate northward due to image efect. The eddy motion produces upwelling (downwelling) in the leading (trailing) edge resulting in dif- ferent responses in the two scenarios examined. In the variable ML depth simulations, Z is fa- vored relative to P because there is no injection of N. On the other hand, in the fxed ML depth simulations, P is favored relative to Z due to dilution. All simulations show P enrichment within the eddy, but winter simulations show a greater response to the physical forcing. We conclude that the cyclonic eddy shed from BC provides favorable conditions for planktonic growth. Winter- like conditions seem to be more favorable than summer-like ones and, therefore, present more intense blooms associated with the ring. 1. Introduction Oceanic frontal regions have been observed as areas of intense biological productivity with high abundance of planktonic or- ganisms (Olson et al., 1994; Bakun, 2006). Such places represent sites where the physical system increases the trophic energy of the biological system by driving the productivity of each trophic level from the “minimal net gain” situation present in the oceanic habitat on a larger scale (Bakun, 2006). It is known that oceanic organisms are strongly infuenced by intense eddy felds associated with frontal jets and rings (isolated eddies) shed from fronts (Olson et al., 1994). McGillicuddy (2016) describes various mechanisms by which mesoscale eddies can afect the chlorophyll distribution in the upper ocean. In addition to trapping and lateral advection of the planktonic communities within and by the eddies, some phenomena related to the eddies – e.g. eddy pumping, eddy-wind interaction, and eddy impacts on https://doi.org/10.1016/j.dynatmoce.2019.101096 Received 6 September 2018; Received in revised form 6 June 2019; Accepted 6 June 2019 ⁎ Corresponding author. E-mail address: pereiraf@usp.br (F. Pereira). Dynamics of Atmospheres and Oceans 87 (2019) 101096 Available online 08 June 2019 0377-0265/ © 2019 Elsevier B.V. All rights reserved. T