Wind relaxation and a coastal buoyant plume north of Pt. Conception, CA: Observations, simulations, and scalings

TitleWind relaxation and a coastal buoyant plume north of Pt. Conception, CA: Observations, simulations, and scalings
Publication TypeJournal Article
Year of Publication2016
AuthorsSuanda S.H, Kumar N., Miller AJ, Di Lorenzo E, Haas K., Cai D.H, Edwards C.A, Washburn L., Fewings M.R, Torres R., Feddersen F
JournalJournal of Geophysical Research-Oceans
Volume121
Pagination7455-7475
Date Published2016/10
Type of ArticleArticle
ISBN Number2169-9275
Accession NumberWOS:000388602200013
Keywordscharacteristic patterns; coastal; coastal oceanography; currents; experiment; modeling-system; numerical models; Ocean dynamics; part i; point conception; point-conception; santa-barbara channel; shelf circulation; southern california bight; variability; wind relaxations
Abstract

In upwelling regions, wind relaxations lead to poleward propagating warm water plumes that are important to coastal ecosystems. The coastal ocean response to wind relaxation around Pt. Conception, CA is simulated with a Regional Ocean Model (ROMS) forced by realistic surface and lateral boundary conditions including tidal processes. The model reproduces well the statistics of observed subtidal water column temperature and velocity at both outer and inner-shelf mooring locations throughout the study. A poleward-propagating plume of Southern California Bight water that increases shelf water temperatures by similar to 5 degrees C is also reproduced. Modeled plume propagation speed, spatial scales, and flow structure are consistent with a theoretical scaling for coastal buoyant plumes with both surface-trapped and slope-controlled dynamics. Plume momentum balances are distinct between the offshore (>30 m depth) region where the plume is surface-trapped, and onshore of the 30 m isobath (within 5 km from shore) where the plume water mass extends to the bottom and is slope controlled. In the onshore region, bottom stress is important in the alongshore momentum equation and generates vertical vorticity that is an order of magnitude larger than the vorticity in the plume core. Numerical experiments without tidal forcing show that modeled surface temperatures are biased 0.5 degrees C high, potentially affecting plume propagation distance and persistence.

DOI10.1002/2016jc011919
Short TitleJ Geophys Res-Oceans
Student Publication: 
No