The sea surface salinity in the tropical Atlantic between 10°S and 30°N—seasonal and interannual variations (1977–1989)

Dessier, Alain; Donguy, Jean-René

doi:10.1016/0967-0637(94)90027-2

Cited by 111 publications

(122 citation statements)

References 24 publications

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“…The lowest value was found at the Caribbean Province (35.9 ± 0.13), probably due to equatorial water that carries a summer seasonal Amazon signal (Dessier and Donguy, 1994), while the high evaporation and lack of riverine inputs close to the NATR Province resulted in higher salinity (37 ± 0.03) for the open ocean region (Fig. 2c).…”

Section: Resultsmentioning

confidence: 99%

Temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean

et al. 2014

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Abstract. The temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean was assessed on the basis of measurements of gross primary production (GPP), community respiration (CR) and net community production (NCP), as well as experimental assessments of the response of CR to temperature manipulations. Metabolic rates were measured at 68 stations along three consecutive longitudinal transects completed during the Malaspina 2010 Expedition, in three different seasons. Temperature gradients were observed in depth and at basin and seasonal scale. The results showed seasonal variability in the metabolic rates, the highest rates being observed during the spring transect. The overall mean integrated GPP / CR ratio was 1.39 ± 0.27 decreasing from winter to summer, and the NCP for the subtropical North Atlantic Ocean during the cruises exhibits net autotrophy (NCP > 0) in about twothirds (66 %) of the total sampled communities. Also, we reported the activation energies describing the temperature dependence of planktonic community metabolism, which was generally higher for CR than for GPP in the subtropical North Atlantic Ocean, as the metabolic theory of ecology predicts. Furthermore, we made a comparison of activation energies describing the responses to in situ temperature in the field (Ea CR = 1.64 ± 0.36 eV) and those derived experimentally by temperature manipulations (Ea CR = 1.45±0.6 eV), which showed great consistency.

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Section: Resultsmentioning

confidence: 99%

Temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean

et al. 2014

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“…This low surface salinity at 10°W has been reported as mainly influenced by the negative Evaporation minus Precipitations budget in the eastern Atlantic [Dessier and Donguy, 1994]. The temperature relative minimum observed at about 1°S (<25°C) is the signature of the boreal summer cold tongue due to the equatorial upwelling, which separates warm surface waters (>25°C) present in both hemispheres (Figure 2c).…”

Section: Mean Salinity and Temperature Section At 10°wmentioning

confidence: 95%

Seasonal variability of the Equatorial Undercurrent at 10°W as inferred from recent in situ observations

Kolodziejczyk¹,

Bourlès²,

Marin³

et al. 2009

J. Geophys. Res.

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[1] Eighteen cross-equatorial shipboard current profiling sections along 10°W with conductivity-temperature-depth measurements taken between 1997 and 2007 are used to analyze the mean meridional structure and the seasonal variability of the Equatorial Undercurrent (EUC) at 10°W. Our analysis suggests a seasonal cycle for the EUC transport at 10°W, with a well-defined annual harmonic and some indication of a semiannual component, with a first maximum in January and a second stronger maximum from June to September. The mean EUC transport at 10°W is estimated to be 12.1 Sv and, compared to earlier estimates farther in the west, at 35°W (20.9 Sv) and 26°W (13.8 Sv). The eastward flow transport exhibits a strong variability at 10°W (with a total range of transports from 7.1 Sv to more than 31.7 Sv). The seasonal amplitude of the eastward flow variability is ±8.9 Sv, from a minimum of 8.2 Sv in November to 25.9 Sv in August. The eastward flows within the thermocline are divided in two parts: a permanent part within the s q = 24.5-26.5 isopycnal layer, with a semiannual cycle, known as the EUC, and a nonpermanent part in the deep thermocline (beneath s q = 26.5 isopycnal), associated with a strong eastward transport (up to 15 Sv) during the boreal summer, that is not observed during the rest of the year. The current at the equator in the deep thermocline is even westward during boreal fall. The disappearance of the salinity core of the EUC during the boreal summer, associated with the upwelling of the hydrological structure at 10°W, reveals that the saline subtropical waters carried by the EUC within the thermocline no longer flow into the Gulf of Guinea during the boreal summer. Our data also show the presence of the South Equatorial Undercurrent (SEUC) at 10°W in the Gulf of Guinea with a strong latitudinal and depth variability throughout the year. The mean SEUC at 10°W is centered near 5°S and is farther south than observed at 35°W and 26°W, suggesting its poleward shift from west to east.

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“…Today the deep-water below 4000 m is warmer and less corrosive to carbonate in the eastern Atlantic than water at comparable depth in the western Atlantic, because the flow of Antarctic bottom water (below 4000 m) from the western basin into the eastern basin is restricted by the topographic barrier of the MidAtlantic Ridge with a sill depth of approximately 3750 m (Metcalfe et al, 1964). a sea-surface salinity minimum (anomaly) extending to Ceara Rise at the end of the summer (Dessier and Donguy, 1994). During the first half of the year, when the intertropical convergence zone (ITCZ) has its southernmost position, the NECC does not exist and the NBCC flows continuously along the coast into the Gulf of Mexico.…”

Section: Factors Controlling Amazon Sediment Discharge To Ceara Risementioning

confidence: 99%

Deep-water circulation, chemistry, and terrigenous sediment supply in the equatorial Atlantic during the Pliocene, 3.3–2.6 Ma and 5–4.5 Ma

Tiedemann¹,

Franz²

1997

Proceedings of the Ocean Drilling Program

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At Sites 925 -929, an orbitally tuned time scale was generated for the Pliocene from 5 to 2.5 Ma by correlating precessional magnetic susceptibility cycles to the 65ûN summer insolation record that was based on the astronomical solution of Laskar et al. (1993).Two Pliocene time intervals were investigated. The time interval from 3.3 to 2.6 Ma includes the intensiÞcation of northern hemisphere glaciation. The second interval from 5 to 4.5 Ma monitors the warmer Pliocene and is believed to reßect a major event in the closure history of the Panama Isthmus. A bathymetric comparison between sand content and carbonate accumulation records suggests that the early Pliocene was marked by stronger carbonate dissolution and a shallower lysocline than the middle Pliocene. A drastic increase in carbonate preservation occurred at about 4.6 Ma that was probably associated with the emergence of the Panama Isthmus. Variations in the lysocline depth were dominated by the 41-k.y. tilt cycle, indicating a strong coupling to high-latitude climate forcing. In contrast, the dominance of precession cycles in less undersaturated water masses well above the lysocline may indicate changes in carbonate production and carbonate ßux. Middle Pliocene maxima in carbonate dissolution at 4356 m water depth lag minima of ice volume by 12 k.y. at the obliquity band, which is typical for Pleistocene PaciÞc records. This phase lag decreased toward shallower water depths returning to the ÒAtlantic typeÓ of carbonate preservation.Cyclic ßuctuations in the supply of Amazon sediments responded with nearly equal concentration of variance to the precession and obliquity periods. The 41-k.y. ßuctuations in the supply of Amazon siliciclastics may result from sea-level changes as inferred from an in-phase relationship with benthic d 18 O. Benthic oxygen isotopes show no response to orbital precession. This suggests that climatological changes in South America and/or changes in the intensity of the North Brazilian Coastal Current are strong candidates in controlling the precessional ßux of terrigenous material to Ceara Rise.

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The sea surface salinity in the tropical Atlantic between 10°S and 30°N—seasonal and interannual variations (1977–1989)

Cited by 111 publications

References 24 publications

Temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean

Temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean

Seasonal variability of the Equatorial Undercurrent at 10°W as inferred from recent in situ observations

Deep-water circulation, chemistry, and terrigenous sediment supply in the equatorial Atlantic during the Pliocene, 3.3–2.6 Ma and 5–4.5 Ma

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