Title | Local and remote forcing of currents and temperature in the central Southern California Bight |
Publication Type | Journal Article |
Year of Publication | 2003 |
Authors | Hickey BM, Dobbins EL, Allen S.E |
Journal | JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS |
Volume | 108 |
Date Published | MAR 15 |
ISSN | 0148-0227 |
Keywords | alongshore pressure gradient, coastal circulation, coastal trapped waves, remote forcing, southern California currents, water temperature |
Abstract | {[}1] A comprehensive study of the central Southern California Bight shows that subtidal currents are dominated by relatively long time scales (10-25 days), large alongshore scales, and significant offshore and upward phase propagation. A one-dimensional model shows that observed fluctuating, poleward propagating (speeds 140-260 cm s(-1)) alongshore pressure gradient disturbances account for a much larger fraction of the alongshore velocity variance than local wind stress (at least 40% in both seasons) and have the longer periods of the dominant currents. With the addition of local wind stress, about half the velocity variance can be accounted for, and overall, about 5% more variance in spring than in summer. Results are consistent with generation of disturbances by remote wind stress several hundred kilometers equatorward of the bight and alongcoast propagation as low-mode coastally trapped waves. The large-scale remote forcing is also responsible for much of the velocity variance on the adjacent shelf, the semienclosed Santa Monica Bay. A nonlinear, three-dimensional model shows that water is pushed into the bay initially as part of a throughflow, later becoming an eddy that gradually fills the bay, producing counterflow on its shoreward side. On the shelf, local alongshore wind stress accounts for only 25% of the velocity variance in spring and none in summer. The large-scale disturbances also produce significant temperature fluctuations throughout the region, via lateral advection of the mean alongshore temperature gradient. Local wind-driven coastal upwelling is responsible for temperature fluctuations on the inner shelf during several 2-4 day events in spring, but only very near the coastal wall. |
DOI | 10.1029/2000JC00313 |