Chaotic analyses of 3D Lagrangian motions in the rotating annulus experiments.

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The purpose of this project is to experimentally study the chaotic phenomena of the atmosphere by carrying out long-term tracking of 3D Lagrangian motions of an air parcel in the rotating annulus experiments. For steady baroclinic waves, we have already completed the experiments and analyses that showed good agreement to the chaotic analyses based on the numerical simulations done by Sugata and Yoden (1994)(Tajima et al, J.Meteor, Soc.Japan, 1999). Here we conveyed the experiments on Hadley flows with the tracking of more than 200 hours. As a result, we could confirm the theoretical result obtained by Robinson (1959) and the numerical analyses done by Williams (1967)(Tajima et al, J.Atmos.Sci., 2000). The subjects for whose studies a Lagrangian view plays an especially important role have been known to be the motions of the air in the stratosphere that transports stratospheric substances such as ozone from the equator to poles and around the polar vortex. In the rotating annulus fluid … More experiments, so far a radial temperature difference has been imposed on the whole depth of the water in the tank to produce Rossby waves which simulate mid-latitude tropospheric waves. Here we succeeded in producing the wave flows in an unstable lower later and axisymmetric flows in a stable stratified upper layer by imposing only near the bottom of the tank and heating the water surface. At first we tried to simulate the upward propagation of the drifting waves that correspond to the tropospheric ones seen in the Southern Hemisphere. Then we introduced the conical bottom to model the beta effect and conducted the experiments on wavenumbers 5, 4 and 3. As a result, only the smaller wavenumber-3 flows were found to distinctively propagate. In the summer hemisphere, all the tropospheric waves are known to be prohibited from propagating. Furthermore, we could confirm the experimental evidence that simulates this fact. In the experiments to simulate the upward propagation of standing waves that corresponds the tropospheric ones produced by the large-scale topographies in the Northern Hemisphere, we found the upward propagation only in wavenumber 2. But we observed some symptom to tell that the waves were not steady so that we would need to carry out these experiments again to confirm the result. We have submitted the paper that describes the results of this project to Journal of Atmospheric Sciences. Less