Monitoring groundwater changes in southern Ontario using GRACE satellite gravity measurements
Notice bibliographique
Résumé
The Gravity Recovery and Climate Experiment satellite mission(s) (GRACE) have been measuring variations in the Earth's gravitational field since 2002. Changes in groundwater, melting glaciers, ocean circulation, and large deformations associated with post-glacial rebound, continental tectonics and earthquakes all produce signals that can be detected and monitored. In this talk, I will provide an introduction to the GRACE missions, briefly mention some new analysis methods being developed at the Canadian Geodetic Survey, and show some new results related to groundwater variations in Southern Ontario. The new method uses watershed regions from the Canadian National Frameworks Dataset to build mascons (regions of interest) for Canada, ensuring that the boundaries of the numerical method correspond to real hydrological boundaries and reducing leakage between adjacent watersheds. Three distinct mascons are designed using watershed geometry that include Lake Huron, Lake Erie, and Lake Ontario and estimates of total water storage (TWS) change are obtained using GRACE data from the Center for Space Research (U. of Texas at Austin) spherical harmonic Release 5 dataset. These TWS estimates are split into a contribution from surface water (SW) change and a common large-scale background signal across Southern Ontario that represents groundwater, soil moisture, snow and ice. The surface water changes are almost entirely due to lake level changes within the Great Lakes and can be compared to water level observations from gauges on the lakes provided by the Canadian Hydrographic Service. The GRACE derived and observed lake level changes agree well with correlations of 0.95, 0.92, and 0.82 for the Lake Huron, Erie, and Ontario regions, respectively. The amplitudes also agree well and, to our knowledge, this is the first study to effectively detect the changing water levels of the different Great Lakes using GRACE. The common background signal is found to have peak to peak variations of ~20 cm equivalent water thickness (EWT) and is compared to 301 wells from across Southern Ontario (data from the Provincial Groundwater Monitoring Network). The signals agree well with a correlation of 0.85. This result has important implications for the relative size and/or dynamics of the groundwater and remaining surface terms (soil moisture, snow and ice). Furthermore, variations in water storage from groundwater are found to be comparable to variations in water storage from the Great Lakes themselves - highlighting the importance that groundwater plays in any water budget of the Great Lakes system. Comparisons between individual groundwater wells and that of GRACE reveal the spatial extent of wells that show regional signals (high correlation) and those that show more local variability (poor correlation). Wells that correlate poorly reveal additional spatial patterns and the influence of local topography, geology, and water usage.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,002 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 tête enseignante, 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 ».