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Record W2107651427

Hydrographic variability in the Irminger Sea

2005· dissertation· en· W2107651427 on OpenAlexaboutno aff
M. Femke de Jong

Bibliographic record

VenueData Archiving and Networked Services (DANS) · 2005
Typedissertation
Languageen
FieldEarth and Planetary Sciences
TopicOceanographic and Atmospheric Processes
Canadian institutionsnot available
Fundersnot available
KeywordsHydrographyOceanographyAdvectionGeologyConvective mixingSalinityClimatologyWater columnWater massTemperature salinity diagramsThermohaline circulationConvectionGeography
DOInot available

Abstract

fetched live from OpenAlex

This thesis deals with the hydrography of the northwestern North Atlantic Ocean, particularly the Irminger Sea. The data sets used for this study include historical observations (since 1950), near-annual observations (since 1990) of the AR7E section from Greenland to Ireland and daily observations (between 2003 and 2008) from two moorings in the centre of the Irminger Sea. A multi-decadal variability is seen in the upper 2 km of the Irminger Sea and the nearby Labrador Sea. This variability includes a maximum in temperature and salinity around 1970 followed by a minimum in the late 1980s and early 1990s followed by an increase until present. This multi-decadal variability seems to be caused by correlating changes in the atmospheric heat flux and the wind stress curl. Deep convective mixing in the Labrador Sea, occurring every 10 year, distributes the sea-to-air heat loss over the water column. Through advection, the convective mixing in the Labrador Sea largely deter mines the hydrography of the North Atlantic. The convectively formed Labrador Sea Water (LSW) spreads to the Irminger Sea (2 year) and the eastward located Iceland Basin (5 year). The LSW decays by advection and lateral mixing with the more saline Icelandic Slope Water. The low temperature and salinity signal of the LSW returns in the North East Atlantic Deep Water in the Irminger Sea, with a delay of 2 year. For the Denmark Strait Overflow Water, the fast hydrographic variability described by Dickson et al. (2003) reappears in the observations included here. Although, the freshening trend observed between 1965 and 2000 changed into a weaker salinifying trend observed between 2001 and 2008. Notably, the range of the sub-annual variability exceed the inter-annual variability at all depths. Denmark Strait Overflow Water (DSOW) shows occasional rapid drops in salinity and temperature as well as a non-linear annual cycle in temperature. Both types of variability are assumed to be related t o changes in the atmospheric forcing over Denmark Strait. In the upper layers, convective mixing down to at least 400 m is seen in each winter in the Irminger Sea. The deepest mixed layers (1000 m) were observed during the cold winter of 2007-2008. The local mixing modifies the Subpolar Mode Water of the central Irminger Sea, and through advection add to the preconditioning of the Labrador Sea. A 1D model study showed that preconditioning is most important for deep convective mixing in the Irminger Sea, more so than in the Labrador Sea. A large part of the heat loss in winter is utilized to remove the stratification over the upper 500 dbar. Very cold and long-lasting winters are needed to reach deep below this level. A model comparison study showed that most coupled climate models have difficulty in simulating the hydrography of the study area. This seems to be due to drift of the oceanographic state during the spin up period of the model and large differences between the simulated and observed mixing regimes.

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)0.002
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesMeta-epidemiology (narrow)
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: Observational
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.170
Threshold uncertainty score1.000

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0020.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.001
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0020.000
Research integrity0.0000.001
Insufficient payload (model declined to judge)0.0000.000

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 head0.010
GPT teacher head0.224
Teacher spread0.214 · 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
Published2005
Admission routes1
Has abstractyes

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