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On the role of domain aspect ratio in the westward intensification of wind-driven surface ocean circulation
  • Nathan Paldor,
  • Kaushal Gianchandani,
  • Hezi Gildor
Nathan Paldor
Hebrew University of Jerusalem

Corresponding Author:nathan.paldor@huji.ac.il

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Kaushal Gianchandani
Hebrew University of Jerusalem
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Hezi Gildor
The Hebrew University
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The two seminal studies on westward intensification, carried out by Stommel and Munk over 70 years ago, are revisited to elucidate the role of the domain aspect ratio (i.e.~meridional to zonal extents of the basin) in determining the width and speed of a western boundary current (WBC). We examine the general mathematical properties of the two models by transforming them to differential problems that contain only two parameters — the domain aspect ratio and the non-dimensional damping (viscous) coefficient. Simple proxies of width and speed (and hence the transport that equals their product) of the WBC are derived from analytical solutions of the non-dimensional vorticity equations in the relevant region of the (damping, aspect ratio) parameter space. These analytically determined proxies are then benchmarked against numerical simulations of the corresponding time-dependent equations. In both models, the three proxies vary as a power law in the domain aspect ratio and in particular, the non-dimensional transport varies linearly with the domain aspect ratio.