Tritium in the Equatorial Atlantic Current System

Östlund, H. Göte; Rinkel, M. O.; Rooth, Claes

doi:10.1029/jc074i018p04535

Cited by 27 publications

(4 citation statements)

References 9 publications

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“…For the years before 1950 and after 2004, we considered that the distributions of tritium content at surface of the ocean were the same as of January 1950 and December 2004, respectively. Additional information about the methodology and the sources can be found in the supporting information [ Andrié et al , ; Bainbridge , ; Bonisch and Schlosser , ; Bowen and Roether , ; Broecker et al , ; CCHDO , ; Dockins et al , ; Dorsey and Peterson , ; Dreisigacker and Roether , ; Gargett et al , ; Östlund et al , ; Jenkins , , , , ; Kakiuchi et al , ; Landa et al , ; Leboucher et al , ; Michel and Williams , ; Michel and Suess , ; Michel et al , ; Mulsow et al , ; Östlund et al , , ; Östlund and Grall , ; Jean‐Baptiste et al , , ; Povinec et al , ; Roether et al , ; Roether , ; Schlosser , ; Schlosser et al , ; Tamuly , ; Top et al , ; Zaucker , ].…”

Section: Model Simulations and Data Setsmentioning

confidence: 99%

Modeling the global bomb tritium transient signal with the AGCM LMDZ‐iso: A method to evaluate aspects of the hydrological cycle

et al. 2016

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Improving the representation of the hydrological cycle in atmospheric general circulation models (AGCMs) is one of the main challenges in modeling the Earth's climate system. One way to evaluate model performance is to simulate the transport of water isotopes. Among those available, tritium is an extremely valuable tracer, because its content in the different reservoirs involved in the water cycle (stratosphere, troposphere, and ocean) varies by order of magnitude. Previous work incorporated natural tritium into Laboratoire de Météorologie Dynamique Zoom (LMDZ)‐iso, a version of the LMDZ general circulation model enhanced by water isotope diagnostics. Here for the first time, the anthropogenic tritium injected by each of the atmospheric nuclear bomb tests between 1945 and 1980 has been first estimated and further implemented in the model; it creates an opportunity to evaluate certain aspects of LDMZ over several decades by following the bomb tritium transient signal through the hydrological cycle. Simulations of tritium in water vapor and precipitation for the period 1950–2008, with both natural and anthropogenic components, are presented in this study. LMDZ‐iso satisfactorily reproduces the general shape of the temporal evolution of tritium. However, LMDZ‐iso simulates too high a bomb tritium peak followed by too strong a decrease of tritium in precipitation. The too diffusive vertical advection in AGCMs crucially affects the residence time of tritium in the stratosphere. This insight into model performance demonstrates that the implementation of tritium in an AGCM provides a new and valuable test of the modeled atmospheric transport, complementing water stable isotope modeling.

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Section: Model Simulations and Data Setsmentioning

confidence: 99%

Modeling the global bomb tritium transient signal with the AGCM LMDZ‐iso: A method to evaluate aspects of the hydrological cycle

et al. 2016

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“… a See section 4. Data sources are Equalant‐III [ Östlund et al , 1969], Circe (W. Roether, unpublished data, 1997), GEOSECS [ Östlund and Brescher , 1982], NAGS [ Östlund , 1984], Meteor ‐56 (W. Roether, unpublished data, 1997), TTO/TAS [ Östlund and Grall , 1987], AJAX (W. J. Jenkins, unpublished data, 1999), SAVE (W. J. Jenkins, unpublished data, 2003), WOCE Global Data Resource (hosted at the U.S. National Oceanographic Data Center, http://woce.nodc.noaa.gov/wdiu/). …”

Section: History Of Surface Water Tritium Concentrationsmentioning

confidence: 99%

Tritium budget of the South Atlantic

Butzin

Roether

2004

J. Geophys. Res.

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[1] Oceanic tritium inventories of the South Atlantic are deduced from tritium observations and are compared with estimated tritium deliveries. In 1993 the total water column tritium inventory between 0°S and 50°S based on World Ocean Circulation Experiment data amounted to 2.88 Â 10 16 TU 81 m 3 (i.e., tritium units decay corrected to 1981; 3.44 Â 10 18 Bq, uncertainty ±10%) with 80% residing in the upper 800 m. This is about 10% higher than observed during the South Atlantic Ventilation Experiment program in 1987-1989 but twice the amount reported for the Geochemical Ocean Sections Study survey [1972][1973]. Maximum tritium water column contents are found in the subtropics, where in 1993 the bomb signal penetrated to approximately 1000 m depth and where the decay-corrected surface water tritium concentrations were highest and still slowly increasing. The total tritium inventories agree with integrated tritium deliveries that were estimated building upon previously published global input functions, adjusted to the conditions of the South Atlantic. The agreement supports the delivery estimates, which by themselves have considerable uncertainty margins. Tritium surface water time histories of the South Atlantic are inferred for the period 1952-1995 by combining the available observations and atmospheric tritium depositions within a simple scheme. The estimated deliveries (effective uncertainty ±30%) and surface water tritium concentrations (±15%) can serve as boundary conditions in water mass dating and for employing tritium in ocean general circulation models.

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“…Our low-level tritium counting facility has been described earlier (Ostlund et al, 1969), and only the most pertinent features will be described here. Of the water sample ("HT" or "HTO"), up to 4.5 g is directly reduced to hydrogen gas, which is used as filling together with a small amount of propane in our ultralow-level counting machine.…”

Section: T R I T I U M Countingmentioning

confidence: 99%

Atmospheric HT and HTO: <i>I. Experimental procedures and tropospheric data 1968-72</i>

Östlund¹,

Mason

1974

Tellus A: Dynamic Meteorology and Oceanography

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A technique was developed for direct field sampling of atmospheric HTO and HT. Airborne, portable, and laboratory versions were implemented, and a comprehensive sampling program begun. The air is passed first through Molecular Sieve t o adsorb the water, then over palladium carried on Molecular Sieve, which oxidizes atmospheric hydrogen and adsorbs the resulting water in situ. Both samples are subsequently extracted from the adsorbers, and the tritium content measured by internal low-level gas counting. Resolution is 4 % of present atmospheric levels. Monitoring of HT and HTO at three stations in the Northern Hemisphere shows that HT does not undergo seasonal fluctuations like HTO, and variations are small around the present mean of about 46 HT molecules per mg air. After the previous rise from pre-nuclear level, the tropospheric HT-inventory has reached a steady state within the past few years. Sampling transects from 40' N t o 65"s in 1971 and 1972 show similar HT levels in the Northern and Southern Hemispheres indicating a long residence time of HT (and hydrogen). The HT appears to have its source at ground level, most likely from nuclear fuel element processing, underground nuclear fusion device detonations, and military and civilian handling of tritium gas. In the troposphere, there is now more tritium as gas (HT or T,) than as HTO (water vapor).

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Tritium in the Equatorial Atlantic Current System

Cited by 27 publications

References 9 publications

Modeling the global bomb tritium transient signal with the AGCM LMDZ‐iso: A method to evaluate aspects of the hydrological cycle

Modeling the global bomb tritium transient signal with the AGCM LMDZ‐iso: A method to evaluate aspects of the hydrological cycle

Tritium budget of the South Atlantic

Atmospheric HT and HTO: <i>I. Experimental procedures and tropospheric data 1968-72</i>

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