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Record W845171216

Stable isotopes as tracers for freshwater fluxes into the North Atlantic

2010· dissertation· en· W845171216 on OpenAlexaboutno aff
K. A. Cox

Bibliographic record

VenueePrints Soton (University of Southampton) · 2010
Typedissertation
Languageen
FieldEarth and Planetary Sciences
TopicArctic and Antarctic ice dynamics
Canadian institutionsnot available
Fundersnot available
KeywordsOceanographyOcean gyreArcticNorth Atlantic Deep WaterSea iceGulf StreamCurrent (fluid)MeltwaterGeologyWater massArctic ice packClimatologyEnvironmental scienceThermohaline circulationGlacial periodFisherySubtropicsPaleontology
DOInot available

Abstract

fetched live from OpenAlex

The Arctic acts as both an indicator and a facilitator of global climate change. Many studies have identified the manifold changes in the Arctic hydrological system resulting from global warming. These changes have affected the freshwater balance of the northern North Atlantic and therefore pose a problem to deep water formation in this region, further impacting the global climate. This thesis uses the quasi-conservative properties of oxygen and hydrogen isotopes in watermasses to identify and quantify the freshwater sources to the ocean currents exiting the Arctic into the northern North Atlantic.
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\nComparison of historical oxygen isotope data from the East Greenland Current system with data presented here indicates that its freshwater isotope signature has not been temporally constant. Specifically, in 2005, there was a shift to a value ? 10 h heavier than the long-term mean, indicating a large increase in sea ice meltwater admixture that coincides with a large, short-term peak in the Fram Strait sea ice export. Therefore, interannual variations in the sea ice export are transported to the watermasses downstream. 
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\nOxygen isotope data from the West Greenland Current confirm that the freshwater signal in the East Greenland Current system is transferred around the tip of Greenland. However, there is an apparent decrease in the freshwater concentration in the West Greenland Current relative to the east. This potentially corroborates the previously reported retroflection of part of the East Greenland Current into the North Atlantic subpolar gyre. The primary freshwater sources to the Labrador Current are identified as Arctic surface waters exported via the Canadian Archipelago, Hudson Strait and the West Greenland Current. There is also considerable sea ice formation and melt influence on the Labrador Shelf.
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\nThe world surface ocean oxygen and hydrogen isotope mixing relationship is observed to be regionally and seasonally robust, with the exception of areas with a high meteoric water influence. The use of hydrogen isotopes as a tracer for Greenland glacial meltwater in the East Greenland Current system is investigated and the preliminary results are positive although further work is necessary to establish the value of this tracer.
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\nThis thesis highlights the importance of stable isotope studies for identifying and quantifying the freshwater in the currents exiting the Arctic, allowing the key pathways of Arctic freshwater into regions of deep water formation in the North Atlantic to be identified and monitored. These pathways are: the East Greenland Current into the Nordic Seas and the North Atlantic subpolar gyre; the West Greenland Current into Labrador Sea; and the Labrador Current into the general North Atlantic circulation.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesInsufficient payload (model declined to judge)
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: Observational
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.297
Threshold uncertainty score0.991

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0010.000
Scholarly communication0.0000.000
Open science0.0010.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0090.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.007
GPT teacher head0.191
Teacher spread0.184 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one teacher head, not a consensus.

Study designObservational
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations4
Published2010
Admission routes1
Has abstractyes

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