Tidal currents and mixing in the Gulf of St. Lawrence: an application of the incremental approach to data assimilation

Authors: Lu Y.; Thompson K.R.; Wright D.G.

Source: Canadian Journal of Fisheries and Aquatic Sciences, Volume 58, Number 4, April 2001 , pp. 723-735(13)

Publisher: NRC Research Press

Abstract:

Tidal heights from 19 tide gauges around the Gulf of St. Lawrence are assimilated into a fully nonlinear, three-dimensional model using the incremental approach to data assimilation. The predicted sea level fields are realistic and agree with the assimilated tidal heights to within about 0.05 m at the M₂ tidal frequency. The model also predicts tidal currents with useful skill. The prediction error at the M₂ tidal frequency is typically less than 0.05 m·s^–1. The maps of predicted tidal currents are used to identify regions of mixed and stratified water in the Gulf of St. Lawrence using a version of the Simpson–Hunter stability parameter, E. Overall, the map of E is in good agreement with a direct measure of water column stability based on observed density profiles.

Les niveaux de la marée enregistrés par 19 marégraphes autour du golfe du Saint-Laurent ont été assimilés dans un modèle tridimensionnel entièrement non-linéaire qui utilise une approche par incréments à l'assimilation des données. L'étendue des niveaux de la mer prédits par le modèle sont réalistes et se conforment aux niveaux de marée assimilés à moins de 0,05 m à une fréquence de marée M₂. Le modèle prédit aussi de façon pratique les courants de marée. L'erreur de la prédiction est généralement moins de 0,05 m·s^–1 à la fréquence de marée de M₂. Les cartes des courants prédits servent à identifier les régions d'eaux mixtes et d'eaux stratifiées du golfe du Saint-Laurent, à l'aide d'une variante du paramètre de stabilité E de Simpson–Hunter. En règle générale, la carte de répartition des E correspond bien aux mesures directes de la stabilité de la colonne d'eau basées sur l'observation des profils de densité.[Traduit par la Rédaction]

Language: English

Document Type: Research article

Publication date: 2001-04-01

• Published continuously since 1901 (under various titles), this monthly journal is the primary publishing vehicle for the multidisciplinary field of aquatic sciences. It publishes perspectives (syntheses, critiques, and re-evaluations), discussions (comments and replies), articles, and rapid communications, relating to current research on cells, organisms, populations, ecosystems, or processes that affect aquatic systems. The journal seeks to amplify, modify, question, or redirect accumulated knowledge in the field of fisheries and aquatic science. Occasional supplements are dedicated to single topics or to proceedings of international symposia.
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