Surface CO2 parameters and air–sea CO2 flux distribution in the eastern equatorial Atlantic Ocean

Koffi, Urbain; Lefèvre, Nathalie; Kouadio, Georges; Boutin, Jacqueline

doi:10.1016/j.jmarsys.2010.04.010

Cited by 19 publications

(43 citation statements)

References 39 publications

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“…Hence, the parameterization of C T includes both physical (S and T ) and/or biological parameters (Bakker et The results of the 10-fold cross-validation analysis showed that a first-order polynome fits C T to S and T with an RMSE of 16.25 µmol kg −1 and r 2 = 0.87. These values are comparable to the RMSE and r 2 found by previous empirical approaches applied in the eastern Atlantic (Bakker et al, 1999;Koffi et al, 2010). However, we found that a third-order polynome improved the RMSE and r 2 of the equation compared to the first-order fit (Eq.…”

Section: Fitting C T In the Mediterranean Sea Surface Waterssupporting

confidence: 89%

Climatological variations of total alkalinity and total dissolved inorganic carbon in the Mediterranean Sea surface waters

et al. 2015

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Abstract. A compilation of data from several cruises between 1998 and 2013 was used to derive polynomial fits that estimate total alkalinity (A T ) and total dissolved inorganic carbon (C T ) from measurements of salinity and temperature in the Mediterranean Sea surface waters. The optimal equations were chosen based on the 10-fold cross-validation results and revealed that second-and third-order polynomials fit the A T and C T data respectively. The A T surface fit yielded a root mean square error (RMSE) of ± 10.6 µmol kg −1 , and salinity and temperature contribute to 96 % of the variability. Furthermore, we present the first annual mean C T parameterization for the Mediterranean Sea surface waters with a RMSE of ± 14.3 µmol kg −1 . Excluding the marginal seas of the Adriatic and the Aegean, these equations can be used to estimate A T and C T in case of the lack of measurements. The identified empirical equations were applied on the 0.25 • climatologies of temperature and salinity, available from the World Ocean Atlas 2013. The 7-year averages (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) showed that A T and C T have similar patterns with an increasing eastward gradient. The variability is influenced by the inflow of cold Atlantic waters through the Strait of Gibraltar and by the oligotrophic and thermohaline gradient that characterize the Mediterranean Sea. The summer-winter seasonality was also mapped and showed different patterns for A T and C T . During the winter, the A T and C T concentrations were higher in the western than in the eastern basin. The opposite was observed in the summer where the eastern basin was marked by higher A T and C T concentrations than in winter. The strong evaporation that takes place in this season along with the ultra-oligotrophy of the eastern basin determines the increase of both A T and C T concentrations.

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Section: Fitting C T In the Mediterranean Sea Surface Waterssupporting

confidence: 89%

Climatological variations of total alkalinity and total dissolved inorganic carbon in the Mediterranean Sea surface waters

et al. 2015

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“…According to Koffi et al (2010); Lefèvre et al (2010), and Bonou et al (2016) in the WTNA, SSS has been shown to be highly correlated with TA and DIC.…”

Section: Discussionmentioning

confidence: 95%

A Synoptic Assessment of the Amazon River-Ocean Continuum during Boreal Autumn: From Physics to Plankton Communities and Carbon Flux

et al. 2017

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The Amazon generates the world's largest offshore river plume, which covers extensive areas of the tropical Atlantic. The data and samples in this study were obtained during the oceanographic cruise Camadas Finas III in October 2012 along the Amazon River-Ocean Continuum (AROC). The cruise occurred during boreal autumn, when the river plume reaches its maximum eastward extent. In this study, we examine the links between physics, biogeochemistry and plankton community structure along the AROC. Hydrographic results showed very different conditions, ranging from shallow well-mixed coastal waters to offshore areas, where low salinity Amazonian waters mix with open ocean waters. Nutrients, mainly NO3− and SiO2−, were highly depleted in coastal regions, and the magnitude of primary production was greater than that of respiration (negative apparent oxygen utilization). In terms of phytoplankton groups, diatoms dominated the region from the river mouth to the edge of the area affected by the North Brazil Current (NBC) retroflection (with chlorophyll a concentrations ranging from 0.02 to 0.94 mg m−3). The North Equatorial Counter Current (NECC) region, east of retroflection, is fully oligotrophic and the most representative groups are Cyanobacteria and dinoflagellates. Additionally, in this region, blooms of cyanophyte species were associated with diatoms and Mesozooplankton (copepods). A total of 178 zooplankton taxa were observed in this area, with Copepoda being the most diverse and abundant group. Two different zooplankton communities were identified: a low-diversity, high-abundance coastal community and a high-diversity, low-abundance oceanic community offshore. The CO2 fugacity (fCO2sw), calculated from total alkalinity (1,450 < TA < 2,394 μmol kg−1) and dissolved inorganic carbon (1,303 < DIC < 2,062 μmol kg−1) measurements, confirms that the Amazon River plume is a sink of atmospheric CO2 in areas with salinities <35 psu, whereas, in regions with salinities >35 and higher-intensity winds, the CO2 flux is reversed. Lower fCO2sw values were observed in the NECC area. The ΔfCO2 in this region was less than 5 μatm (−0.3 mmol m−2 d−1), while the ΔfCO2 in the coastal region was approximately 50 μatm (+3.7 mmol m−2 d−1). During the cruise, heterotrophic and autotrophic processes were observed and are indicative of the influences of terrestrial material and biological activity, respectively.

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“…Using the SSS recorded at the mooring with the highest available resolution (hourly in 2006 and 2007; daily in 2008 and 2009), TA was calculated with the relationship determined by Koffi et al (2010). The standard error on the predicted alkalinity is ±7.2 μmol kg −1 .…”

Section: Methodsmentioning

confidence: 99%

Sea water fugacity of CO<sub>2</sub> at the PIRATA mooring at 6°S, 10°W

Parard¹,

Lefèvre²,

Boutin

2010

Tellus B: Chemical and Physical Meteorology

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A B S T R A C TIn order to better understand the variability of surface CO 2 in the Tropical Atlantic, a CARIOCA sensor has been installed on a PIRATA mooring at 6 • S, 10 • W in June 2006. The fugacity of CO 2 (f CO 2 ) is recorded hourly from 7 June 2006 to 30 October 2009 with two important data gaps. From July to September, an upwelling develops and a decrease in sea surface temperature (SST) is observed, associated with an f CO 2 increase. However, the highest f CO 2 is observed in October, after the upwelling season, due to the warming of surface waters. The region is a net source of CO 2 to the atmosphere of 2.10 ± 0.69 mol m −2 yr −1 in 2007. The monthly flux is maximum (3.21 ± 0.8 mol m −2 yr −1 ) in November (averaged over 2006 and 2008). High frequency variability is observed throughout the time series but is particularly pronounced after the upwelling season. Biological and thermodynamic processes explain the diurnal variability. Dissolved inorganic carbon (DIC) is calculated from (alkalinity) TA and f CO 2 using an empirical TAsalinity relationship determined for the eastern equatorial Atlantic. Net community production (NCP) is calculated from DIC daily changes and ranges from 9 to 41 mmol m −2 d −1 , which is consistent with previous measurements in this region.

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Surface CO2 parameters and air–sea CO2 flux distribution in the eastern equatorial Atlantic Ocean

Cited by 19 publications

References 39 publications

Climatological variations of total alkalinity and total dissolved inorganic carbon in the Mediterranean Sea surface waters

Climatological variations of total alkalinity and total dissolved inorganic carbon in the Mediterranean Sea surface waters

A Synoptic Assessment of the Amazon River-Ocean Continuum during Boreal Autumn: From Physics to Plankton Communities and Carbon Flux

Sea water fugacity of CO<sub>2</sub> at the PIRATA mooring at 6°S, 10°W

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Surface CO2 parameters and air–sea CO2 flux distribution in the eastern equatorial Atlantic Ocean

Cited by 19 publications

References 39 publications

Climatological variations of total alkalinity and total dissolved inorganic carbon in the Mediterranean Sea surface waters

Climatological variations of total alkalinity and total dissolved inorganic carbon in the Mediterranean Sea surface waters

A Synoptic Assessment of the Amazon River-Ocean Continuum during Boreal Autumn: From Physics to Plankton Communities and Carbon Flux

Sea water fugacity of CO<sub>2</sub> at the PIRATA mooring at 6&#xb0;S, 10&#xb0;W

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Sea water fugacity of CO<sub>2</sub> at the PIRATA mooring at 6°S, 10°W