Wind Drag and Relative Separations of Undrogued Drifters

Kirwan, A. D.; McNally, G.; Pazan, Stephen E.

doi:10.1175/1520-0485(1978)008<1146:wdarso>2.0.co;2

Cited by 22 publications

(9 citation statements)

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“…This result was however obtained for drifters with a drogue depth of only about 30 m, and is thus relevant to drifters which measure the dynamics in the surface mixed layer and which are strongly influenced by the local atmospheric (and wave) forcing. Drifters with a much larger drogue depth are by contrast thought to behave differently, following more closely the large and mesoscale flows below the surface mixed layer (Kirwan et al, 1978(Kirwan et al, , 1979Large and Van Loon, 1989;Krauss et al, 1989). Thus, because of the quite large drogue depth of the drifters studied here, we consider the drifter trajectories to be fairly representative, at sufficiently large scales, of the real fluid parcel trajectories.…”

Section: Description Of Datamentioning

confidence: 96%

Fractal drifter trajectories in the Kuroshio extension

Osborne¹,

Kirwan

Provenzale³

et al. 1989

Tellus A: Dynamic Meteorology and Oceanography

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We study the fractal and scaling properties of the Lagrangian trajectories of three satellitetracked, freely drifting buoys (drifters) placed in the Kuroshio extension region during 1977. Over a period of about one year, the drifters, whose positions followed approximately the motions of fluid parcels in the near-surface layer, traveled almost the entire width of the Pacific Ocean. During this time, the drifters followed what may be described as highly erratic paths, while on the average being advected eastward in the zonal flow. Here we apply four different data analysis methods, based on the mathematics of fractals, to the drifter paths. We find that for space scales extending from at least 20 to 150 km and time scales from 1 .S days to 1 week, each of the trajectories displays fractal and scaling behavior with a fractal dimension of approximately 1.3. The multifractal nature of the drifter trajectories is also explored. The implication of these results is that the near-surface Lagrangian mesoscale motions in the Kuroshio Extension exhibit fractal properties in a range of scales normally attributed to geophysical fluid dynamical turbulence. These results evidently provide the first experimental evidence that fluid parcel trajectories in large-scale Ocean flows can exhibit fractal behavior. A relation between the observed value of the fractal dimension and the properties of the power spectrum of a typical drifter position coordinate is also exploited. We finally discuss some of the possible physical implications of these results for the study of geophysical fluid dynamical flows.

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Section: Description Of Datamentioning

confidence: 96%

Fractal drifter trajectories in the Kuroshio extension

Osborne¹,

Kirwan

Provenzale³

et al. 1989

Tellus A: Dynamic Meteorology and Oceanography

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“…Slippage of the buoys due to direct wind pressure on their hulls is also thought to be only a small source for error. Kirwan et al [1978] attempted to apply theoretical corrections to the tracks of low-profile buoys in the North Pacific, but found that even small corrections (amounting to slightly more than 1% of the 10-m winds) resulted in surface drifts which were upwind for brisk winds. They used the logarithmic profile to estimate the mean winds at the level of the buoys, but according to Krugermeyer et al [1978] waves cause the mean winds within about three wave heights of the sea surface to be reduced from those of the logarithmic profile.…”

Section: Residual Drifts During Nearly Steady Conditionsmentioning

confidence: 99%

Drifter trajectories through a current meter array at Drake Passage

Peterson¹

1985

J. Geophys. Res.

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Six low‐profile undrogued buoys drifted through the Drake Passage during 1979 where an extensive array of current meters was moored. Geostrophic currents at the buoy positions are estimated by extrapolating the shallow 40‐hour low‐pass filtered current measurements to the surface by using vertical shear relationships derived from hydrographie stations taken over a 5‐year period within the passage. The buoy tracks are also filtered, followed by the removal of the extrapolated geostrophic currents. The residual drifts are then compared with the 10‐m winds, which are estimated twice daily by applying the similarity theory for a neutral barotropic boundary layer to sea level atmospheric pressure fields. The residual drifts are found to respond within a few hours to variations in the wind. Buoy motions against the interior flow, persisting for as long as 6 days, along with loops and reversals which are not observed in the subsurface currents are well accounted for by the wind. During times of nearly steady wind conditions the residual drift is found to average 3.4%±1.4% of the 10‐m wind speed at 25.0°±12.0° to the left of the wind.

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“…Indeed, surplus personnel parachutes have been used as underwater drogues -e.g. -one class of ocean drifting buoy (o1 m in dimension) used a 9.2 m personnel parachute, suspended at 35 m depth (Kirwan et al, 1975(Kirwan et al, , 1978.…”

Section: Options For Influencing the Drift Trajectorymentioning

confidence: 99%

Voyage across Ligeia Mare: Mechanics of sailing on the hydrocarbon seas of Saturn׳s Moon, Titan

Lorenz

2015

Ocean Engineering

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Wind Drag and Relative Separations of Undrogued Drifters

Cited by 22 publications

References 0 publications

Fractal drifter trajectories in the Kuroshio extension

Fractal drifter trajectories in the Kuroshio extension

Drifter trajectories through a current meter array at Drake Passage

Voyage across Ligeia Mare: Mechanics of sailing on the hydrocarbon seas of Saturn׳s Moon, Titan

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