Diffusion by Continuous Movements

Taylor, G. I.

doi:10.1112/plms/s2-20.1.196

Cited by 2,149 publications

(1,611 citation statements)

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“…This table shows the total number of floats (Nrf), the calculated integral timescale ( ), the variance u 2 and the calculated diffusivity K for the different dataset (IABP, TOPAZ and neXtSIM) and time periods used in this study. All these Lagrangian statistics were computed following the diffusion theory of Taylor (1921) and using L = 1000 km and T = 250 days as averaging scales to calculate the Lagrangian mean velocities. regime transition occurs corresponds to the integral timescale = 1.71 days.…”

Section: Resultsmentioning

confidence: 99%

“…Using such decomposition for studying pollutant transport by sea ice was already proposed by Colony and Thorndike (1985), who analyzed sea-ice drift data covering the period 1893-1984 while using arbitrary averaging scales (90 years and 1500 km) to define the mean motion. By using a denser sea-ice drift dataset covering the period 1978-2001 and the theoretical framework introduced by Taylor (1921) for the analysis of turbulent fluids, Rampal et al (2009b) proposed a methodology to rigorously decompose sea-ice motion into mean and turbulent-like fluctuating parts. The appropriate averaging scales (about 400 km and 5.5 months for winter conditions) were found small enough to clearly separate the interannual variability of the mean circulation from the fluctuating motion due to passing atmospheric perturbations, local oceanic eddies and inertial and tidal motion.…”

Section: Introductionmentioning

confidence: 99%

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Arctic sea-ice diffusion from observed and simulated Lagrangian trajectories

et al. 2016

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Abstract. We characterize sea-ice drift by applying a Lagrangian diffusion analysis to buoy trajectories from the International Arctic Buoy Programme (IABP) dataset and from two different models: the standalone Lagrangian sea-ice model neXtSIM and the Eulerian coupled ice-ocean model used for the TOPAZ reanalysis. By applying the diffusion analysis to the IABP buoy trajectories over the period 1979-2011, we confirm that sea-ice diffusion follows two distinct regimes (ballistic and Brownian) and we provide accurate values for the diffusivity and integral timescale that could be used in Eulerian or Lagrangian passive tracers models to simulate the transport and diffusion of particles moving with the ice. We discuss how these values are linked to the evolution of the fluctuating displacements variance and how this information could be used to define the size of the search area around the position predicted by the mean drift. By comparing observed and simulated sea-ice trajectories for three consecutive winter seasons (2007)(2008)(2009)(2010)(2011), we show how the characteristics of the simulated motion may differ from or agree well with observations. This comparison illustrates the usefulness of first applying a diffusion analysis to evaluate the output of modeling systems that include a sea-ice model before using these in, e.g., oil spill trajectory models or, more generally, to simulate the transport of passive tracers in sea ice.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Arctic sea-ice diffusion from observed and simulated Lagrangian trajectories

et al. 2016

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“…Note that the emergence of a dual spectrum in 2D turbulence requires forcing at a narrow range of scales and the spectrum tends toward E{k) ~ k for the more typical oceanic case of broad-band forcing (Lesieur, 1997). At the asymptotic limit of very long times and particle separations, when all particle correlations diminish, the so-called diffusive regime, D 2 (t) = 2K7, where K is the diffusivity coefficient, should be attained (Taylor, 1921).…”

Section: (3)mentioning

confidence: 99%

Relative dispersion from a high-resolution coastal model of the Adriatic Sea

et al. 2008

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“…To test the validity of these assumptions, both sides of Taylor's theorem (Taylor, 1921) can be calculated independently (Freeland et al, 1975) and compared. The specific calculation chosen here again follows the description given in Figueroa and Olson (1989), with the exception of subtracting an ensemble mean velocity before integrating the velocity data rather than the individual floats' mean velocity.…”

Section: Eddy Diffusion In the Tropical Gyrementioning

confidence: 99%

Kinematic elements of Antarctic Intermediate Water in the western South Atlantic

Boebel

Schmid

Zenk

1999

Deep Sea Research Part II: Topical Studies in Oceanography

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The northward flowing Antarctic Intermediate Water (AAIW) is a major contributor to the large-scale meridional circulation of water masses in the Atlantic. Together with bottom and thermocline water, AAIW replaces North Atlantic Deep Water that penetrates into the South Atlantic from the North. On the northbound propagation of AAIW from its formation area in the south-western region of the Argentine Basin, the AAIW progresses through a complex spreading pattern at the base of the main thermocline. This paper presents trajectories of 75 subsurface floats, seeded at AAIW depth. The floats were acoustically tracked, covering a period from December 1992 to October 1996. Discussions of selected trajectories focus on mesoscale kinematic elements that contribute to the spreading of AAIW. In the equatorial region, intermittent westward and eastward currents were observed, suggesting a seasonal cycle of the AAIW flow direction. At tropical latitudes, just offshore the intermediate western boundary current, the southward advection of an anticyclonic eddy was observed between 5°S and 11°S. Farther offshore, the flow lacks an advective pattern and is governed by eddy diffusion. The westward subtropical gyre return current at about 28°S shows considerable stability, with the mean kinetic energy to eddy kinetic energy ratio being around one. Farther south, the eastward deeper South Atlantic Current is dominated by large-scale meanders with particle velocities in excess of 60 cm s\ . At the Brazil-Falkland Current Confluence Zone, a cyclonic eddy near 40°S 50°W seems to act as injector of freshly mixed AAIW into the subtropical gyre. In general, much of the mixing of the various blends of AAIW is due to the activity of mesoscale eddies, which frequently reoccupy similar positions.

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Diffusion by Continuous Movements

Cited by 2,149 publications

References 0 publications

Arctic sea-ice diffusion from observed and simulated Lagrangian trajectories

Arctic sea-ice diffusion from observed and simulated Lagrangian trajectories

Relative dispersion from a high-resolution coastal model of the Adriatic Sea

Kinematic elements of Antarctic Intermediate Water in the western South Atlantic

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