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See detailSeasonal and inter-annual variability of air-sea CO2 fluxes and seawater carbonate chemistry in the Southern North Sea
Gypens, N.; Lacroix, G.; Lancelot, C. et al

Poster (2011, April 08)

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See detailSeasonal and inter-annual variability of air-sea CO2 fluxes and seawater carbonate chemistry in the Southern North Sea
Gypens, N.; Lacroix, G.; Lancelot, C. et al

in Progress in Oceanography (2011), 88(1-4), 59-77

A 3D coupled biogeochemical–hydrodynamic model (MIRO-CO2&CO) is implemented in the English Channel (ECH) and the Southern Bight of the North Sea (SBNS) to estimate the present-day spatio-temporal ... [more ▼]

A 3D coupled biogeochemical–hydrodynamic model (MIRO-CO2&CO) is implemented in the English Channel (ECH) and the Southern Bight of the North Sea (SBNS) to estimate the present-day spatio-temporal distribution of air–sea CO2 fluxes, surface water partial pressure of CO2 (pCO2) and other components of the carbonate system (pH, saturation state of calcite (Xca) and of aragonite (Xar)), and the main drivers of their variability. Over the 1994–2004 period, air–sea CO2 fluxes show significant interannual variability, with oscillations between net annual CO2 sinks and sources. The inter annual variability of air–sea CO2 fluxes simulated in the SBNS is controlled primarily by river loads and changes of biological activities (net autotrophy in spring and early summer, and net heterotrophy in winter and autumn), while in areas less influenced by river inputs such as the ECH, the inter annual variations of air–sea CO2 fluxes are mainly due to changes in sea surface temperature and in near-surface wind strength and direction. In the ECH, the decrease of pH, of Xca and of Xar follows the one expected from the increase of atmospheric CO2 (ocean acidification), but the decrease of these quantities in the SBNS during the considered time period is faster than the one expected from ocean acidification alone. This seems to be related to a general pattern of decreasing nutrient river loads and net ecosystem production (NEP) in the SBNS. Annually, the combined effect of carbon and nutrient loads leads to an increase of the sink of CO2 in the ECH and the SBNS, but the impact of the river loads varies spatially and is stronger in river plumes and nearshore waters than in offshore waters. The impact of organic and inorganic carbon (C) inputs is mainly confined to the coast and generates a source of CO2 to the atmosphere and low pH, of Xca and of Xar values in estuarine plumes, while the impact of nutrient loads, highest than the effect of C inputs in coastal nearshore waters, also propagates offshore and, by stimulating primary production, drives a sink of atmospheric CO2 and higher values of pH, of Xca and of Xar. [less ▲]

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See detailModeling present-day spatial and seasonal variability of carbon dioxide in surface waters of the Southern Bight of the North Sea
Gypens; Borges, Alberto ULiege; Lancelot, C et al

Conference (2009)

The 3D ecological MIRO&CO-CO2 model is used to describe the spatial and seasonal variations of air-sea CO2 exchanges in the English Channel and the Southern Bight of the North Sea receiving important ... [more ▼]

The 3D ecological MIRO&CO-CO2 model is used to describe the spatial and seasonal variations of air-sea CO2 exchanges in the English Channel and the Southern Bight of the North Sea receiving important nutrient and carbon river loads. Runs are performed for years 2003 and 2004 using actual sea water temperature, light, wind speed and river forcings. MIRO&CO-CO2 simulations show large spatial and seasonal variations of surface pCO2 (range 100 - 600 ppm). Significant under- (and over-) saturation are simulated in spring (and summer) due to the dominance of auto- (and heterotrophic) activities. The highest pCO2 values are simulated in the vicinity of river mouths. Similarly, the computed annual air-sea CO2 fluxes varies spatially, predicting sources of CO2 to the atmosphere near estuaries but moderate sinks (or neutral) in offshore waters. Sensitivity studies are further performed to estimate the contribution of organic and inorganic carbon and nutrient river loads on the air-sea CO2 flux simulated in the area. [less ▲]

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See detailRemotely sensed seasonal dynamics of phytoplankton in the Ligurian Sea in 1997-1999
Nezlin, N. P.; Lacroix, G.; Kostianoy, A. G. et al

in Journal of Geophysical Research. Oceans (2004), 109(C07013),

[1] Remotely sensed data and a one-dimensional hydrophysical model were used to study the seasonal dynamics of surface plant pigments concentration in the Ligurian-Provencal basin. The variations of ... [more ▼]

[1] Remotely sensed data and a one-dimensional hydrophysical model were used to study the seasonal dynamics of surface plant pigments concentration in the Ligurian-Provencal basin. The variations of phytoplankton biomass were estimated from the observations of the Coastal Zone Color Scanner ( 1978 - 1986) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ( September 1997 to October 1999) radiometers. The factors of physical environment analyzed included remotely sensed sea surface temperature ( from advanced very high resolution radiometers), wind, air temperature, and atmospheric precipitation. The Geohydrodynamics and Environment Research (GHER) model was used to explain the observed correlations between the physical forcing and the response of phytoplankton biomass. The general pattern of phytoplankton seasonal dynamics was typical to subtropical areas: maximum biomass during cold season from October to April and low biomass during summer months. The intensity of winter/spring bloom significantly varied during different years. The correlation was revealed between the summer/autumn air temperature contrast ( expressed as the difference between the air temperatures in August and in November) and the maximum monthly averaged surface chlorophyll concentration during the subsequent winter/spring bloom. The features of seasonal dynamics of phytoplankton are regulated by the physical impacts influencing water stratification. The difference between two seasonal cycles ( from September 1997 to October 1999) illustrates the response of phytoplankton growth to local meteorological conditions. In March - April 1999 the vernal bloom was much more pronounced; it resulted from deeper winter cooling and more intensive winter convection. Heating of surface water layer, wind mixing, and freshwater load with rains and river discharge either stimulate or depress the development of phytoplankton, depending on what limiting environmental factor ( light or nutrient limitation) prevailed. [less ▲]

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See detailRegional modelling of the biogeochemical cycles in the Western Mediterranean (EROS 2000)
Djenidi, Salim ULiege; Martin, J. M.; Beckers, Jean-Marie ULiege et al

in Barthel, K. G.; Bohle-Carbonell, C.; Weydert, M. (Eds.) Marine Sciences and technologies (1993)

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