Coastal ocean variability in the US Pacific Northw

Authors: Scott M Durski Alexander L Kurapov John S Allen P Michael Kosro Gary D Egbert R Kipp Shearman John A Barth

Publish Date: 2015/10/26

Volume: 65, Issue: 12, Pages: 1643-1663

PDF Link

Abstract

A 2km horizontal resolution ocean circulation model is developed for a large coastal region along the US Pacific Northwest 34–50N to study how continental shelf slope and interior ocean variability influence each other The model has been run for the time period September 2008–May 2011 driven by realistic surface momentum and heat fluxes obtained from an atmospheric model and lateral boundary conditions obtained from nesting in a global ocean model The solution compares favorably to satellite measurements of sea surface temperature and sea surface height observations of surface currents by highfrequency radars mooring temperature time series and glider temperature and salinity sections The analysis is focused on the seasonal response of the coastal ocean with particular emphasis on the winter circulation patterns which have previously garnered relatively little attention Interannual variability is examined through a comparison of the 2009–2010 winter influenced by El Niño and the winters in the preceding and following years Strong northward winds combined with reduced surface cooling along the coast north of Cape Mendocino 404N in winter 2009–2010 resulting in a vigorous downwelling season characterized by relatively energetic northward currents and warmer ocean temperatures over the continental shelf and upper slope An analysis of the time variability of the volumeaveraged temperature and salinity in a coastal control volume CV that extends from 41 to 47N and offshore from the coast to the 200m isobath clearly shows relevant integrated characteristics of the annual cycle and the transitions between winter shelf circulation forced by northward winds and the summer circulation driven primarily by southward upwellingfavorable winds The analysis also reveals interesting interannual differences in these characteristics In particular the CV volumeaverage temperature remains notably warmer during January–March 2010 of the El Niño winterThis research was supported by the National Science Foundation NSF grants OCE1030922 OCE0527168 and OCE0961999 the National Aeronautics and Space Administration NASA grant NNX13AD89G and the National Oceanic and Atmospheric Administration NOAA through the Coastal Ocean Modeling Testbed COMT program and the Northwest Association of Networked Ocean Observing Systems NANOOS the Regional Association of the national Integrated Ocean Observing System grant NA11NOS0120036

Keywords: