Journal cover Journal topic
Nonlinear Processes in Geophysics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.699 IF 1.699
  • IF 5-year value: 1.559 IF 5-year
    1.559
  • CiteScore value: 1.61 CiteScore
    1.61
  • SNIP value: 0.884 SNIP 0.884
  • IPP value: 1.49 IPP 1.49
  • SJR value: 0.648 SJR 0.648
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 52 Scimago H
    index 52
  • h5-index value: 21 h5-index 21
Volume 16, issue 4
Nonlin. Processes Geophys., 16, 557–568, 2009
https://doi.org/10.5194/npg-16-557-2009
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: Nonlinear processes in oceanic and atmospheric flows

Nonlin. Processes Geophys., 16, 557–568, 2009
https://doi.org/10.5194/npg-16-557-2009
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.

  27 Aug 2009

27 Aug 2009

Surface mixing and biological activity in the four Eastern Boundary Upwelling Systems

V. Rossi1,2, C. López2, E. Hernández-García2, J. Sudre1, V. Garçon1, and Y. Morel3 V. Rossi et al.
  • 1Laboratoire d'Études en Géophysique et Océanographie Spatiale, CNRS, Observatoire Midi-Pyrénées, 14 avenue Edouard Belin, Toulouse, 31401 Cedex 9, France
  • 2Instituto de Física Interdisciplinar y Sistemas Complejos IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
  • 3Service Hydrographique et Océanographique de la Marine, (SHOM), 42 avenue Gaspard Coriolis, 31057 Toulouse, France

Abstract. Eastern Boundary Upwelling Systems (EBUS) are characterized by a high productivity of plankton associated with large commercial fisheries, thus playing key biological and socio-economical roles. Since they are populated by several physical oceanic structures such as filaments and eddies, which interact with the biological processes, it is a major challenge to study this sub- and mesoscale activity in connection with the chlorophyll distribution. The aim of this work is to make a comparative study of these four upwelling systems focussing on their surface stirring, using the Finite Size Lyapunov Exponents (FSLEs), and their biological activity, based on satellite data. First, the spatial distribution of horizontal mixing is analysed from time averages and from probability density functions of FSLEs, which allow us to divide each areas in two different subsystems. Then we studied the temporal variability of surface stirring focussing on the annual and seasonal cycle. We also proposed a ranking of the four EBUS based on the averaged mixing intensity. When investigating the links with chlorophyll concentration, the previous subsystems reveal distinct biological signatures. There is a global negative correlation between surface horizontal mixing and chlorophyll standing stocks over the four areas. To try to better understand this inverse relationship, we consider the vertical dimension by looking at the Ekman-transport and vertical velocities. We suggest the possibility of a changing response of the phytoplankton to sub/mesoscale turbulence, from a negative effect in the very productive coastal areas to a positive one in the open ocean. This study provides new insights for the understanding of the variable biological productivity in the ocean, which results from both dynamics of the marine ecosystem and of the 3-D turbulent medium.

Publications Copernicus
Download
Citation