Laboratory model of two-dimensional polar beta-plane turbulence
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The evolution of a two-dimensional turbulent decaying flow is experimentally analyzed in a rotating system considering the effect of the change of the Coriolis force with latitude. The flow is generated using an electro-magnetic (EM) cell, i.e., by electro-magnetically forcing a thin layer of a saline solution, in a rotating reference frame. A Feature Tracking (FT) technique is used to measure the flow field allowing the reconstruction of high resolution velocity and vorticity fields. In agreement with theoretical prediction and previous experiments, results corresponding to high values of the beta parameter show a preferential transfer of energy towards zonal modes and the consequent organization of a weak anticyclonic circulation in the polar zone. Moreover, the analysis of the one-dimensional energy spectra shows a scaling steeper than Kolmogorov’s law and a peak near the Rhines scale indicating a soft barrier of the energy transfer towards low wave-numbers.
KeywordsParticle Image Velocimetry Potential Vorticity Feature Tracking Particle Tracking Velocimetry Inverse Cascade
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