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Extreme surface and near-bottom currents in the northwest Atlantic
journal contributionposted on 2023-05-17, 16:10 authored by Oliver, ECJ, Sheng, J, Thompson, KR, Urrego Blanco, JR
This study presents a methodology for estimating extreme current speeds from numerical model results using extremal analysis techniques. This method is used to estimate the extreme near-surface and near-bottom current speeds of the northwest Atlantic Ocean with 50-year return periods from 17 years of model output.The non-tidal currents produced by a threedimensional ocean circulation model for the 1988–2004 period were first used to estimate and map the 17-year return period extreme current speeds at the surface and near the bottom. Extremal analysis techniques (i.e., fitting the annualmaxima to the Type I probability distribution) are used to estimate and map the 50-year extreme current speeds. Tidal currents are dominant in some parts of the northwest Atlantic, and a Monte Carlo-based methodology is developed to take into account the fact that large non-tidal extrema may occur at different tidal phases. The inclusion of tidal currents in this way modifies the estimated 50-year extreme current speeds, and this is illustrated along several representative transects and depth profiles. Seasonal variations are examined by calculating the extreme current speeds for fall-winter and spring–summer. Finally, the distribution of extreme currents is interpreted taking into account (1) variability about the time-mean current speeds, (2) wind-driven Ekman currents, and (3) flow along isobaths.
Publication titleNatural Hazards
Department/SchoolInstitute for Marine and Antarctic Studies
Place of publicationVan Godewijckstraat 30, Dordrecht, Netherlands, 3311 Gz
Rights statementCopyright 2012 Springer Science+Business Media B.V.