Laboratory Experiments Investigating Zonal Jets Using Altimetry
2014 OCCI Project
AbstractThe banded organization of clouds and zonal (i.e. east-west) winds is one of the most striking features of the atmosphere of Jupiter and Saturn. Recently zonal jets were also discovered in the Earth’s ocean, although their signal is weaker than other dynamical features and are only revealed as a result of time averaging. The coarseness of today’s climate models does not resolve these zonal jets, which appear to be largely a result of the interaction between eddies and zonal flows. Numerical simulations show that the regime of the flow is controlled by the β parameter, related to the sphericity of the earth, and the flow velocity fluctuations. The jets in the Earth’s oceans seem to be in a transitional regime, but could a more energetic climate move the Earth’s oceans towards the zonostrophic regime characteristic of the jets on the gas giants Jupiter and Saturn? Would that affect the climate? We need an understanding of zonal jets to begin to answer these questions.
I propose to conduct experiments in the Geophysical Fluid Dynamics (GFD) Laboratory 2-m rotating platform using the altimetry technique to measure velocity of the mesoscale and submesocale. A large platform is necessary to separate viscous scales from the zonal jet scales. I plan to conduct a parameter study varying the β parameter and the forcing (i.e. velocity fluctuations) to advance our understanding of the dynamics of these relatively newly discovered oceanic zonal jets and suggest a physically based parameterization for climate models. Finally, the role of submesoscale flows (e.g. filaments and streamers) has been put forward as a likely candidate for the dissipation of energy accumulated at the larger scales, i.e. mesoscale. The proposed velocity measurements will help in understanding how the energy accumulating at these large scales is dissipated.