Author(s): M. Cobas-Garcia; M. Ruiz-Villarreal; M. E. Vazquez-Cendon; P. Otero; L. M. Garcia-Garcia
Linked Author(s): Ana Pérez Otero
Keywords: No Keywords
Abstract: We present in this paper an application of a mathematical model to oceanic circulation at coastal scales. Objectives: The aim of this study is to gain a better understanding of the processes that may play a role in the development of Harmful Algal Blooms (HABs). The study focuses on the HAB that took place during Autumn 2005 on the Portuguese and North-West Spanish coast, where the Paralytic Shellfish Poison (PSP) toxin was found, showing a northward propagation pattern. Hypothesis have been posed that these pattern could be explained by means of an inshore poleward current that is set up after the cessation of upwelling. The main objective of this study is to perform computer simulations with an ocean circulation model to study the oceanic conditions that could have affected the development of this bloom, with the perspective of this hypothesis. Material and methods: The Regional Ocean Modelling System (ROMS) is a free surface, terrain-following, primitive equation ocean model that represents the state-of-the-art in ocean modelling. This model was used to simulate the period of interest, forced with atmospheric data provided by the HIRLAM model, used at the Spanish Meteorological Agency. A sensitivity study was conducted, to test the importance of the different parameters of the model (bathymetry smoothing, of layers, vertical coordinate parameters) by means of comparisons with data from different datasets available (buoys, moorings, oceanographic cruises, satellite sst images, etc. ). Results: Model results show a good agreement with measurements. All the simulations performed to the present show an inshore poleward current consistent with the hypothesis, with different intensities, although further simulations are being carried out. Conclusions: We present an application of a state-of-the-art ocean model to a HAB case. The simulations show that the phenomenon is mainly wind-driven, and that the numerical simulations provide a means to better understand general circulation in the area, and the conditions that could affect the development of the bloom.
Year: 2010