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Record W1971586516 · doi:10.1029/2002jc001532

Cross‐shore migration of lunate megaripples during Duck94

2004· article· en· W1971586516 on OpenAlexaff
Amani Ngusaru, Alex E. Hay

Bibliographic record

VenueJournal of Geophysical Research Atmospheres · 2004
Typearticle
Languageen
FieldEarth and Planetary Sciences
TopicCoastal and Marine Dynamics
Canadian institutionsDalhousie UniversityMemorial University of Newfoundland
Fundersnot available
KeywordsGeologySwashCrestSurf zoneSignificant wave heightSubmarine pipelineLongshore driftWave heightAmplitudeSediment transportStormOrbital speedSwellGeomorphologyGeodesySeismologyWind waveSedimentPhysicsOceanography

Abstract

fetched live from OpenAlex

Remote acoustic observations of lunate megaripple migration are presented from two storm events during the Duck94 nearshore dynamics experiment for time periods during which longshore currents were weak (<20 cm/s). During these periods, significant wave orbital velocities were 50–80 cm/s; megaripple heights were 0.05–0.5 m; megaripple horns were directed shoreward; the crest‐to‐trough slope of the shoreward advancing ripple face was close to the angle of repose; and migration speeds were 10–40 cm/h onshore. The observations also indicate that the megaripples stalled, and may have begun to migrate offshore, when the mean offshore flow exceeded 20 cm/s during the second storm. Stress‐based bed load sediment transport models are moderately successful in predicting the observed dependence of migration velocity on measured fluid velocities separated into zero (mean current), infragravity wave, and sea‐and‐swell wave frequency bands. Wave and mean current friction factors, f w and f c , are obtained by best fit between the predicted and observed migration velocities, for two choices (3/2 and 5/2) for the stress exponent ξ in the bed load transport part of the model. Net transport is computed using wave velocity amplitudes determined from both run length statistics and wave by wave. Improved agreement with observations is obtained for the wave‐by‐wave net transport predictions and for the wave‐like treatment of the infragravity band. The level of agreement is relatively insensitive to the value of ξ. The best fit current and wave friction factor values, for ξ = 5/2 and 3/2 are f c = 4.3 × 10 −3 and 8.0 × 10 −3 and f w = 1.7 × 10 −2 and 4.8 × 10 −2 , respectively.

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)0.001
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: Observational
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.181
Threshold uncertainty score0.994

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0010.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0010.000

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 head0.019
GPT teacher head0.292
Teacher spread0.272 · 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.

The models applied no category: nothing in the taxonomy fit this work.
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

Citations21
Published2004
Admission routes1
Has abstractyes

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