Spirals on the sea

By W. Munk, L. Armi, K. Fischer, F. Zachariasen. Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 2000

329 citations recorded by the source corpus.

Spiral eddies were first seen in the sunglitter on the Apollo Mission 30 years ago; they have since been recorded on synthetic aperture radar (SAR) images and in the infrared. We present a small sample of images. The spirals are broadly distributed over the world's oceans, 10–25 km in size and overwhelmingly cyclonic. Under light winds favourable to visualization, linear surface features with high surfactant density and low surface roughness are of common occurrence. The linear features are wound into spirals in vortices associated with horizontal shear instability, modified by rotation, in regions where the shear is comparable with the Coriolis frequency. Two models for concentrating shear are presented: a softened version of the classical sharp Margules front, and the time–dependent Lagrangian model of Hoskins & Bretherton. Horizontal shear instabilities and both frontal models favour cyclonic shear and cyclonic spirals, but for different reasons.

Subfields: Earth-Surface Processes, Oceanography

View Paper: https://www.semanticscholar.org/paper/5c0bbbf7c123a3775d4dc6bd45863872d20228b7

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In Earth-Surface Processes

In Oceanography

Citations in the corpus

Parameterization of Mixed Layer Eddies. Part I. Theory and Diagnosis (2008, background): “The troposphere and its surface boundary layer provide two analogous types of instability (Blumen 1979; Nakamura 1988).”
The physical oceanography of the transport of floating marine debris (2020, background): “Satellite observations are essential to complement numerical simulations in locating fronts (e.g. Rascle et al 2014), eddies, gyres and plumes, sometimes through tracking surfactants (Munk et al 2000), making it possible to identify potential zones of accumulation in the open ocean.”
Direct measurements of ocean surface velocity from space: Interpretation and validation (2005, background): “[2] Over the last 40 years, numerous spaceborne optical and radar observations have revealed surface signatures related to the dynamics of the upper ocean at mesoscale and sub-mesoscale [e.g., Fu and Holt, 1983; Johannessen et al., 1991, 1996;Munk et al., 2000].”
Internal wave detection using the Moderate Resolution Imaging Spectroradiometer (MODIS) (2007, background): “In addition, there is a geometry dependence that will cause either the rough or smooth zones on the surface to appear either bright or dark depending on if the zones are contained in what Munk et al. [2000] describe as the inner ‘‘glitter’’ or outer ‘‘glitter’’ regions.”
Small-scale open-ocean currents have large effects on wind-wave heights (2017, unknown): “Small-scale ocean dynamical patterns have been detected from remote sensing data [e.g., Munk et al., 2000], but a quantitative evaluation of their magnitude and importance emerged only recently from the analysis of numerical model results [e.g., Capet et al., 2016; Klein and Lapeyre, 2009; Sasaki…”
Mixed Layer Instabilities and Restratification (2007, background): “Munk et al. (2000) and Rudnick (2001) find that eddies in the upper ocean at scales between 1 and 20 km are predominantly cyclonic.”