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Alongshelf Variability of Inner-Shelf Circulation along the Central Oregon Coast during Summer

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Title Alongshelf Variability of Inner-Shelf Circulation along the Central Oregon Coast during Summer
Names Kirincich, Anthony R. (creator)
Barth, John A. (creator)
Date Issued 2009-06 (iso8601)
Abstract The spatial and temporal variability of inner-shelf circulation along the central Oregon coast during the
2004 upwelling season is described using a 70-km-long array of moorings along the 15-m isobath. Circulation
at three stations located onshore of a submarine bank differed from that of a station north of the bank,
despite the relatively uniform wind forcing and inner-shelf bathymetry present. During upwelling-favorable
winds, strong southward alongshelf flow occurred north of the bank, no alongshelf flow occurred onshore of
the northern part of the bank, and increasing southward flow occurred onshore of the southern part of the
bank. During downwelling-favorable winds, strong northward flow occurred in the inner shelf onshore of the
bank while weak flow occurred north of the bank. These alongshelf differences in inner-shelf circulation were
due to the effects of the bank, which isolated the inner shelf onshore of the bank from the regional upwelling
circulation that was evident at the northernmost station. As a result, circulation onshore of the bank was
driven primarily by local wind forcing, while flow north of the bank was only partially driven by local winds.A
secondary mode of variability, attributed to the movement of the regional upwelling jet due to remote
forcings, contributed the bulk of the variability observed north of the bank. With the time-dependent wind
forcing present, acceleration was an important term in the depth-averaged alongshelf momentum equation at
all stations. During upwelling, bottom stress and acceleration opposed the wind stress north of the bank,
while bottom stress was weaker onshore of the bank where the across-shelf momentum flux and the
alongshelf pressure gradient balanced the residual of the acceleration and stresses. During downwelling,
waters onshore of the bank surged northward at magnitudes much larger than that found north of the bank.
These spatial variations developed as the season progressed and the regional upwelling circulation intensified,
explaining known variations in growth and recruitment of nearshore invertebrate species.
Genre Article
Identifier Kirincich, Anthony R., John A. Barth, 2009: Alongshelf Variability of Inner-Shelf Circulation along the Central Oregon Coast during Summer. J. Phys. Oceanogr., 39, 1380–1398.

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