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| Titel |
An Application of Lagrangian Coherent Structures to Harmful Algal Blooms |
| VerfasserIn |
M. J. Olascoaga, F. J. Beron-Vera, L. E. Brand, H. Koçak |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250028492
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| Zusammenfassung |
| Karenia brevis is present in low concentrations in vast areas of the Gulf of Mexico (GoM).
This toxic dinoflagellate sporadically develops blooms anywhere in the GoM, except in the
southern portion of West Florida Shelf (WFS). There, these harmful algal blooms
(HABs) are recurrent events whose frequency and intensity are increasing. HABs on
the WFS are usually only evident once they have achieved high concentrations
that can be detected by observation of discolored water, which may be apparent
in satellite imagery; by ecological problems such as fish kills; or human health
problems. Because the early development stages of HABs are usually not detected,
there is limited understanding of the environmental conditions that lead to their
development.
Analysis of simulated surface ocean currents reveals the presence of a persistent
large-scale Lagrangian coherent structure (LCS) on the southern portion of the WFS. A LCS
can be regarded as a distinguished material line which divides immiscible fluid regions with
distinct advection properties. Consistent with satellite-tracked drifter trajectories, this LCS on
the WFS constitutes a cross-shelf barrier for the lateral transport of passive tracers. We
hypothesize that such a LCS provides favorable conditions for the development of HABs.
LCSs are also employed to trace the early location of an observed HAB on the WFS. Using a
simplified population dynamics model we infer the factors that could possibly lead to the
development of this HAB. The population dynamics model determines nitrogen in
two components, nutrients and phytoplankton, which are assumed to be passively
advected by simulated surface ocean currents. Two nutrient sources are inferred for the
HAB whose evolution is found to be strongly tied to the simulated LCSs. These
nutrient sources are found to be located near shore and likely due to land runoff. |
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