A multi-decadal hindcast of a physical–biogeochemical model and derived oceanographic indices in the Bay of Biscay

Type Article
Date 2013-01
Language English
Author(s) Huret MartinORCID1, Sourisseau Marc3, Petitgas Pierre2, Struski Caroline2, Leger Fabien4, Lazure PascalORCID3
Affiliation(s) 1 : IFREMER, STH LBH, F-29280 Plouzane, France.
2 : IFREMER, EMH, F-44311 Nantes 03, France.
3 : IFREMER, Dept DYNECO, F-29280 Plouzane, France.
4 : LEGOS OMP, F-31400 Toulouse, France.
Meeting XII International Symposium on Oceanography of the Bay of Biscay
Source Journal Of Marine Systems (0924-7963) (Elsevier Science Bv), 2013-01 , Vol. 109 , P. S77-S94
DOI 10.1016/j.jmarsys.2012.02.009
WOS© Times Cited 29
Note Projects RECLAIM (“Resolving Climate Impact on fish stocks”, FP6 —Contract 044133), UNCOVER (“Understanding the mechanisms of stock recovery”, FP6 — Contract 022717) and REPROdUCE of the ERA-NET MARIFISH (Contract ERAC(CT-2006-025989)
Keyword(s) Physical-biogeochemical model, Hindcast, Skill assessment, Environmental indices, Seasonal pattern, Interannual variability, Fisheries oceanography, Bay of Biscay
Abstract Multiple year oceanographic simulations (hindcast) are identified as a priority oceanography product for fisheries and environment studies since they provide a unique continuous long-term dataset allowing integrated assessment of the ocean state and evolution. We performed a 37 year (1972–2008) hindcast run with a coupled physical–biogeochemical model in the Bay of Biscay. The coupled model and the hindcast configuration are described. A model skill assessment is performed with a large set of in-situ data. Average seasonal currents show major circulation patterns over the shelf. Among tracers, temperature and salinity have the best agreement, ahead of nitrates and silicates, chlorophyll, and finally phosphates and ammonium. For chlorophyll, improved pattern statistics are found when compared to monthly composites of satellite-derived chlorophyll data. From the hindcast, we derived indices related to mesoscale activity (eddies, plumes, fronts, stratification) and production (chlorophyll and primary production). They help characterise the evolution of the environment in a functional way, on both the seasonal and multi-decadal scales. From these indices, first, a multivariate analysis reveals an increasing number of years that deviate from the mean seasonal pattern. Second, we propose interpretations of the simulated increasing trends detected in several of them (temperature, thermocline depth and primary production). We also recommend further developments to confirm these simulated evolutions, from addition of open boundary forcing with a global circulation model, to the improvement of the dynamics of nutrient regeneration and of the seasonal variability of secondary production. As a perspective, we review the different applications made from our hindcast in relation to anchovy life cycle, a species of major interest in the Bay of Biscay
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