Tritium and90Sr in North Atlantic surface water

Dreisigacker, E.; Roether, Wolfgang

doi:10.1016/0012-821x(78)90104-8

Cited by 110 publications

(81 citation statements)

References 16 publications

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“…Indeed, levels of tritium on the continent are generally higher compared to those in the oceans because on land, rainwater re-evaporates without significant dilution. Note that the EMed surface-water tritium concentrations have always exceeded those in the WMed due to reduced influence of the Atlantic, for which the tritium surface water concentrations have generally been lower (Dreisigacker and Roether, 1978).…”

Section: Tracer Boundary Conditionsmentioning

confidence: 99%

Modelling of the anthropogenic tritium transient and its decay product helium-3 in the Mediterranean Sea using a high-resolution regional model

et al. 2015

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Abstract. This numerical study provides the first simulation of the anthropogenic tritium invasion and its decay product helium-3 ( 3 He) in the Mediterranean Sea. The simulation covers the entire tritium ( 3 H) transient generated by the atmospheric nuclear weapons tests performed in the 1950s and early 1960s and is run till 2011. Tritium, helium-3 and their derived age estimates are particularly suitable for studying intermediate and deep-water ventilation and spreading of water masses at intermediate/deep levels. The simulation is made using a high-resolution regional model NEMO (Nucleus for European Modelling of the Ocean), in a regional configuration for the Mediterranean Sea called MED12, forced at the surface with prescribed tritium evolution derived from observations. The simulation is compared to measurements of tritium and helium-3 performed along large-scale transects in the Mediterranean Sea during the last few decades on cruises of R/V Meteor: M5/6, M31/1, M44/4, M51/2, M84/3, and R/V Poseidon: 234. The results show that the input function used for the tritium generates a realistic distribution of the main hydrographic features of the Mediterranean Sea circulation. In the eastern basin, the results highlight the weak formation of Adriatic Deep Water in the model, which explains its weak contribution to the Eastern Mediterranean Deep Water (EMDW) in the Ionian sub-basin. It produces a realistic representation of the Eastern Mediterranean Transient (EMT) signal, simulating a deep-water formation in the Aegean subbasin at the beginning of 1993, with a realistic timing of deep-water renewal in the eastern basin.

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Section: Tracer Boundary Conditionsmentioning

confidence: 99%

Modelling of the anthropogenic tritium transient and its decay product helium-3 in the Mediterranean Sea using a high-resolution regional model

et al. 2015

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“…Med. constrained by transient tracers commonly used tritium input function (TIF) for the North Atlantic was obtained by Dreisigacker and Roether (1978) and further developed for the EMed by Roether et al (1992). Based on this data set, another TIF for the EMed was created by R. Steinfeldt (unpublished data) where the data after 1974 was extrapolated by using the decay function of tritium.…”

Section: Radioactive Transient Tracersmentioning

confidence: 99%

Ventilation of the Mediterranean Sea constrained by multiple transient tracer measurements

Stöven

Tanhua

2014

Ocean Sci.

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Abstract. Ventilation is the primary pathway for atmosphere-ocean boundary perturbations, such as temperature anomalies, to be relayed to the ocean interior. It is also a conduit for gas exchange between the interface of atmosphere and ocean. Thus it is a mechanism whereby, for instance, the ocean interior is oxygenated and enriched in anthropogenic carbon. The ventilation of the Mediterranean Sea is fast in comparison to the world ocean and has large temporal variability. Here we present transient tracer data from a field campaign in April 2011 that sampled a unique suite of transient tracers (SF 6 , 3 H and 3 He) in all major basins of the Mediterranean. We apply the transit time distribution (TTD) model to the data in order to constrain the mean age, the ratio of the advective / diffusive transport and the number of water masses significant for ventilation.We found that the eastern part of the eastern Mediterranean can be reasonably described with a one-dimensional inverse Gaussian TTD (IG-TTD), and thus constrained with two independent tracers. The ventilation of the Ionian Sea and the western Mediterranean can only be constrained by a linear combination of IG-TTDs. We approximate the ventilation with a one-dimensional, two inverse Gaussian TTD (2IG-TTD) for these areas and demonstrate a possibility of constraining a 2IG-TTD from the available transient tracer data. The deep water in the Ionian Sea has a mean age between 120 and 160 years and is therefore substantially older than the mean age of the Levantine Basin deep water (60-80 years). These results are in contrast to those expected by the higher transient tracer concentrations in the Ionian Sea deep water. This is partly due to deep water of Adriatic origin having more diffusive properties in transport and formation (i.e., a high ratio of diffusion over advection), compared to the deep water of Aegean Sea origin that still dominates the deep Levantine Basin deep water after the Eastern Mediterranean Transient (EMT) in the early 1990s. The tracer minimum zone (TMZ) in the intermediate of the Levantine Basin is the oldest water mass with a mean age up to 290 years. We also show that the deep western Mediterranean has contributed approximately 40 % of recently ventilated deep water from the Western Mediterranean Transition (WMT) event of the mid-2000s. The deep water has higher transient tracer concentrations than the mid-depth water, but the mean age is similar with values between 180 and 220 years.

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“…The flux of new production out of the surface by smaller suspended particles not caught by traps has been shown in at least one case (at Bermuda) to be more than 50% of the large particle flux [Altabet, 1989]. Furthermore, there is increasing evidence from both measurements and models that a large fraction of the flux of new production out of the surface may be as dissolved organic matter [e.g., Suzuki et where T t is the average concentration in the interior box (essentially a measure of the inventory), Ts is the concentration at the surface given by Dreisigacker and Roether [1978], and rbox is the "ventilation" time, which represents the effect of advective, diffusive, and convective exchange between the thermocline and surface waters. Jenkins [1980] used essentially the same approach to find ventilation time scales from tritium and helium 3 measurements in the Sargasso Sea, assuming that the few measurements he had were representative of the entire recirculation region.…”

Section: Introductionmentioning

confidence: 99%

Oxygen and nitrate new production and remineralization in the North Atlantic subtropical gyre

Sarmiento¹,

Thiele²,

Key³

et al. 1990

J. Geophys. Res.

104

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Tritium and90Sr in North Atlantic surface water

Cited by 110 publications

References 16 publications

Modelling of the anthropogenic tritium transient and its decay product helium-3 in the Mediterranean Sea using a high-resolution regional model

Modelling of the anthropogenic tritium transient and its decay product helium-3 in the Mediterranean Sea using a high-resolution regional model

Ventilation of the Mediterranean Sea constrained by multiple transient tracer measurements

Oxygen and nitrate new production and remineralization in the North Atlantic subtropical gyre

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