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.

Item Type:	Refereed Article
Keywords:	extreme current speeds, extremal analysis, northwest atlantic, ocean circulation model, monte carlo methods
Research Division:	Earth Sciences
Research Group:	Oceanography
Research Field:	Physical Oceanography
Objective Division:	Environment
Objective Group:	Climate and Climate Change
Objective Field:	Climate Variability (excl. Social Impacts)
UTAS Author:	Oliver, ECJ (Dr Eric Oliver)
ID Code:	82914
Year Published:	2012
Web of Science® Times Cited:	3
Deposited By:	IMAS Research and Education Centre
Deposited On:	2013-02-22
Last Modified:	2016-09-27
Downloads:	0