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ARTICLE IN PRESS
Continental Shelf Research 30 (2010)127–137
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Continental Shelf Research
journal homepage: www.elsevier.com/locate/csr
Dispersion in the Yucatan coastal zone: Implications for red tide events
˜ Cecilia Enriquez n, Ismael J Marino-Tapia, Jorge A Herrera-Silveira
Departamento de Recursos del Mar, Cinvestav, Km 6 Carretera Antigua a Progreso, Cordemex, 97310, A.P. 73, Merida, Yuc., Mexicoa r t i c l e in fo
Article history: Received 21 July 2008 Received in revised form 17 September 2009 Accepted 8 October 2009 Available online 30 October 2009 Keywords: Yucatan Current Wind-driven circulation Campeche Bank HABs Hydrodynamics
The mechanisms governing dispersion processes in the northern Yucatan coast are investigated using a barotropic numerical model of coastalcirculation, which includes wind-generated and large scale currents (i.e. Yucatan Current). This work provides the foundations for studying the dispersion of harmful algal blooms (HABs) in the area. Modelling experiments include effects of climatic wind (from long term monthly mean NCEP reanalysis), short term wind events (from in situ point measurements), and Yucatan Current (YC) characteristics. Itsmagnitude was approximated from published reports, and its trajectory from geostrophic current ﬁelds derived from altimeter data. These provided a range of real and climatic conditions to study the routes in which phytoplankton blooms may travel. The 2-D model results show that a synthetic and conservative bloom seeded in the Cabo Catoche (CC) region (where it usually grows), moves along thecoast to the west up to San Felipe (SF), where it can either move offshore, or carry on travelling westwards. The transport to the west up to SF is greatly inﬂuenced by the trajectory, intensity and proximity of the YC jet to the peninsula, which enhances the westward circulation in the Yucatan Shelf. Numerical experiments show that patch dispersion is consistently to the west even under the inﬂuenceof northerly winds. When the YC ﬂows westward towards the Campeche Bank, momentum transfer caused by the YC jet dominates the dispersion processes over wind stress. On the other hand, when it ﬂows closer to Cuba, the local processes (i.e. wind and bathymetry) become dominant. Coastal orientation and the Coriolis force may be responsible for driving the patch offshore at SF if external forcingdecreases. & 2009 Elsevier Ltd. All rights reserved.
1. Introduction The coastal sea of the northern Yucatan Peninsula (Fig. 1) has a wide and shallow continental shelf (up to 245 km wide with a nearly monotonic 1/1000 slope). It is located between the Caribbean Sea and the Gulf of Mexico, two ecosystems communicated through the Yucatan Channel, which is 196 km wide and reaches 2000 m depth. The YCﬂows through this channel, carrying with it different water masses. This current can generate a dynamic upwelling pushing cold and nutrient-rich water uphill across the steep continental slope, reaching the Yucatan Shelf where it is dispersed at the bottom (Cochrane, 1969; Merino, 1992; Merino 1997; Ruiz-Renteria, 1979; Sahl et al., 1997). This upwelling provides conditions for development of...