Chaotic Lagrangian Motion and Heat Transport in a Steady, Baroclinic Annulus Wave

Abstract

Lagrangian motion in a steady, Baroclinic annulus wave is investigated numerically by following a tracer particle trajectory for a long period. Even for the regular Eulerian flow field of steady waves, the trajectory shows a chaotic nature, which is an example of "Lagrangian turbulence". However, the chaotic trajectory has some organized structures depending on its position in the annulus. Based on the structure, the annulus of fluid is divided into the following regions: the upper-level and lower-level jets, the cyclonically and anticyclonically trapped regions, and the inner, outer and lower boundary layers. Some isolated regions in which the marked particle has never stayed for that period are also found inside the cyclonically trapped region and around the anticyclonically trapped region. Statistics over the long period show a preferred cyclic route of the region transitions: the outer boundary layer-the upper-level jet -the inner boundary layer-the lower-level jet or the lower boundary layer-the outer boundary layer. The number of dwell periods of the particle in the trapped regions is much smaller than that in the cyclic route, but the average time of one stay in the trapped regions is longer.A Lagrangian view of the heat transport in the steady annulus wave is obtained: The fluid particle absorbs a large amount of heat in the outer boundary layer and releases it in the inner boundary layer, while it nearly conserves its temperature in the interior regions. Inward heat transport is small in every one cycle of the meander of the jets.

Laboratory Experiments of Lagrangian Motions in a Steady Baroclinic Wave

“…Comparing the present observations with the results of the numerical simulations by Sugata and Yoden (1994), we obtained several detailed structures of the flow. The main results can be summarized in the following: (1) The structures of the vortices are composed of the core region, which is rather well isolated, and next to the core the transition zone where fluid particles are frequently transported to and from its outside, but rarely to the core region; (2) The core region in both high-and low-pressure vortices is split into separate upper and Here, use is made of the same symbols as in Fig.…”

“…On the other hand, a recent study by Sugata and Yoden (1994), hereafter referred to as SY, numerically investigated the Lagrangian motion of a fluid particle in a steady baroclinic wave by tracing the particle trajectory for a long period of time (see the introduction of SY for a review of Lagrangian studies of fluid particle motions). As schematically illustrated in Fig.…”

Time Threshold Diagnostics

“…We can not conclude how and why the jet core functions as a potential barrier without further works. Sugata and Yoden (1994) showed clearly how a fluid parcel moves in a jet stream in a steady baroclinic wave in a rotating annulus fluid. The parcel repeats large meanders in the jet stream, where the projection of the trajectory of the parcel on a meridional plane is flat and elliptic and the direction of the movement is the one with an indirect circulation.…”

Experimental Observations of 3-D Lagrangian Motion in a Steady Baroclinic Wave

“…Flierl,1981;Pierrehumbert, 1991;Moses and Steinberg, 1986). Sugata and Yoden (1994), hereafter referred to as SY, investigated the Lagrangian motion in a steady baroclinic wave of wavenumber-5 by tracing a marked fluid particle for a long time in a numerical solution of their model (Sugata and Yoden, 1993). As was schematically shown in our previous papers (Tajima and Nakamura, 1995;Tajima et al, 1995aTajima et al, , 1995b, the steady baroclinic wave has been well known to have the following basic structure: the upper (UJ, eastward)-and lower (U, Jwestward)-level jets, the high (HV)-and low (LV)-pressure vortices, and the inner (TB)-, outer (OB)-and lower (LB)-boundary layers.…”

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AbstractChaotic Lagrangian motion in a steady baroclinic wave, which is highly relevant to meteorological and oceanographical problems, was investigated by Sugata and Yoden (1994) by tracing a marked fluid particle for a long time in a numerical solution of their model. To test their result, we have conducted experiments on steady Baroclinic waves in a differentially-heated rotating fluid annulus by tracking a 3-D trajectory of one neutrally buoyant tracer particle suspended in the fluid for a long time.

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