Modelling the impact of a La Niña event on a South West Pacific Lagoon.
In view of increasing environmental awareness and biodiversity conservation, understanding the main forcing mechanism driving biogeochemical cycles in coral reefs and lagoon coastal areas is a priority. La Niña events cause unbalanced situations in the Equatorial Pacific and result in enhanced precipitation in South West Pacific coastal areas. We investigated the impact of heavy rainfalls during the 2008 La Niña event on the New Caledonia lagoon using a 3D coupled on-line hydrodynamic-biogeochemical model. Simulations and data showed that the whole lagoon was impacted by river inputs and stronger hydrodynamics, enhancing chlorophyll-a concentration by a factor between 1.7 and 1.9. The coupled model provided new insights into plume transport, highlighting that eastern plumes can be advected northwards or can reach the South West Lagoon, depending on the balance between regional, tide-induced, and wind-induced surface currents. It also provided a synoptic view of lagoon biogeochemical-hydrodynamic response, when remote sensing data are not available due to cloud coverage.
Mediterranean Institute of Oceanography-MIO, Aix-Marseille Université, 13288 Marseille Cedex 09, France. rosalie.fuchs@univ-amu.fr
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Fuchs
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Dupouy
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Douillet
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Caillaud
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Mangin
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Pinazo
D059000:El Nino-Southern Oscillation; D004784:Environmental Monitoring; D005618:Fresh Water / Q000032:analysis / Q000737:chemistry; D008962:Models, Theoretical; D010140:Pacific Ocean; D012621:Seasons; D012623:Seawater / Q000737:chemistry*