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

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• 作者：Sutara H. Suanda ; Nirnimesh Kumar ; Arthur J. Miller ; Emanuele Di Lorenzo ; Kevin Haas ; Donghua Cai ; Christopher A. Edwards ; Libe Washburn ; Melanie R. Fewings ; Rachel Torres ; et al
• 刊名：Journal of Geophysical Research: Oceans
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：121
• 期：10
• 页码：7455-7475
• 全文大小：6.3MB
• ISSN：2169-9291

文摘

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 ruct="true" class="math-equation-construct">rue" class="math-equation-image">rue" class="math-equation-mathml" style="display:none">rg/1998/Math/MathML">r="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">≈ 5°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°C high, potentially affecting plume propagation distance and persistence.