Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 12, issue 2
Biogeosciences, 12, 299–305, 2015
https://doi.org/10.5194/bg-12-299-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 12, 299–305, 2015
https://doi.org/10.5194/bg-12-299-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 16 Jan 2015

Research article | 16 Jan 2015

Satellite observations of the small-scale cyclonic eddies in the western South China Sea

F. Liu1, S. Tang2, and C. Chen2 F. Liu et al.
  • 1School of Marine Sciences, Sun Yat-sen University, Guangzhou 510006, China
  • 2State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China

Abstract. High-resolution ocean color observations offer an opportunity to investigate the oceanic small-scale processes. In this study, the Medium Resolution Imaging Spectrometer (MERIS) daily 300 m data were used to study small-scale processes in the western South China Sea. It is indicated that the cyclonic eddies with horizontal scales of 10 km are frequently observed during the upwelling season of each year over the 2004–2009 period. These small-scale eddies were generated in the vicinity of the southern front of the cold tongue, and then propagated eastward with a speed of approximately 12 cm s−1. This propagation speed was consistent with the velocity of the western boundary current. As a result, the small-scale eddies kept the high levels of phytoplankton rotating away from the coastal areas, resulting in the accumulation of phytoplankton in the interior of the eddies. The generation of the small-scale eddies may be associated with strengthening of the relative movement between the rotation speed of the anticyclonic mesoscale eddies and the offshore transport. With the increases of the normalized rotation speed of the anticyclonic mesoscale eddies relative to the offshore transport, the offshore current became a meander under the impacts of the anticyclonic mesoscale eddies. The meandered cold tongue and instability front may stimulate the generation of the small-scale eddies. Unidirectional uniform wind along the cold tongue may also contribute to the formation of the small-scale eddies.

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In this paper, small-scale cyclonic eddies in the western South China Sea were observed during the upwelling season of the year. These small-scale eddies propagated eastward at the speed of 12cm/s. They transported the high level of phytoplankton away from the coastal area. The generation of the small-scale eddies may be associated with the relative movement between the mesoscale anticyclonic eddy and the offshore current.
In this paper, small-scale cyclonic eddies in the western South China Sea were observed during...
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