Advances in upward looking sonar technology for studying the processes of change in Arctic Ocean ice climate
Notice bibliographique
Résumé
A major impetus for scientific studies of climate change in the Arctic Ocean has been the reduction in the areal extent and thickness of its sea ice cover. An extended measurement record of the horizontal dimensions of this ice cover is available for the full Arctic Ocean Basin based upon a record compiled from more than 30 years of relatively continuous satellite based measurements. Unfortunately, data accumulations for the ice cover’s vertical dimension, ie, sea ice thickness, tend to be limited to data sets with durations no longer than 15 years, reflecting underlying greater measurement difficulties. Moreover, the longest duration ice thickness data collection efforts have been confined only to two specific portions of the Basin, namely, Fram Strait and the Canadian sector of the Beaufort Sea. Elsewhere, the available data sets are either of notably shorter duration or non-existent.Upward-looking sonar (ULS) has been and continues to be the primary source of data with volumes and accuracy sufficient for meaningfully monitoring ice thickness. Originally deployed from polar-traversing submarines during the Cold War, the limited amounts and accessibility of the collected data stimulated development of purpose-built sea-floor moored ULS instrumentation which, beginning in the late 1980s, began to supply the bulk of newly acquired ice draft and ice under-surface topography data. Technological advances have subsequently led to new generations of ULS instruments including ice-profiling sonar (IPS), incorporating much expanded on-board data storage capacities (69 Mbytes to 8 Gbytes) and powerful real-time firmware which now allow unprecedented temporal (ping rates of up to 1Hz) and horizontal resolution of ice topography. These instruments operate autonomously during one year or longer deployments, returning draft data on time and spatial scales of 1s and 1m or better, respectively, which are essential to understandings of mechanical and thermodynamical aspects of sea ice processes. Such processes govern ocean-atmosphere exchanges in polar waters, thereby determining ice extent and thickness parameters. The larger data storage capacities of the newest instruments also allow collection of additional information associated with acoustic returns from different levels in the upper water column and the lower ice cover. Such data have potential for improving understandings of ice processes occurring during the initial freeze-up and early consolidation phases of sea ice growth on the basis of acoustic backscatter from frazil, grease, shuga and nilas ice forms. With International Polar Year programmes now well underway, ice profiling instruments, sharing a common technology, are and/or will be deployed in unprecedented numbers from both fixed subsurface moorings and drifting buoys. This deployment commitment holds great promise for delivery of data with both temporal and spatial detail and areal coverage sufficient to strongly upgrade present capabilities for monitoring and modelling ice cover change.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,002 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,002 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».