Boris Galperin
Associate Professor
Physical Oceanography
Ph.D., Technion-Israel Institute of Technology, 1982
Office Phone: (727) 553-1249
Email: bgalperin@usf.edu
Informational Study Group
Zonal Jets and Eddies - Planetary Science and Satellite Oceanography at the Crossroads
Research Interests
My research at USF has been focused on large-scale atmospheric and planetary circulations, generation and maintenance of zonal jets, advanced spectral turbulence theories, and numerical modeling of estuarine and shelf circulation.
During the last decade, an extensive numerical and theoretical research of quasi-two-dimensional (2D) turbulence on the beta-plane and on the surface of a rotating sphere has been undertaken. We have discovered a new, strongly anisotropic turbulence regime that has been coined zonostrophic turbulence. Being a subset of geostrophic turbulence, it is distinguished by a strongly anisotropic spectrum and stable systems of alternating zonal jets. We have found an evidence of this spectrum in zonal velocity profiles observed on the giant planets of our Solar System and in high-resolution simulations of the global terrestrial ocean. The zonostrophic turbulence underlies the processes responsible for the generation and maintenance of zonal jets both in idealized 2D flows and in real world, 3D, rotating flows with a small Burger number. Indeed, systems of alternating zonal jets have been observed on all four solar giant planets, in most eddy-resolving simulations of the global oceanic circulation and some ocean data, in the maps of the mean velocity deduced from the satellite altimetry, and in the laboratory experiment with a small-scale forcing and a topographic beta-effect which was conducted in the Coriolis turntable at Grenoble, France; all these flows feature a small Burger number.
Along with the studies of anisotropic turbulence in a quasi-2D environment, turbulence anisotropy has also been investigated in smaller-scale 3D flows. A new spectral theory has been developed based upon successive small-scale modes elimination in the assumption of the quasi-normal statistics of turbulent fluctuations. This theory has been coined a Quasi-Normal Scale Elimination (QNSE). When the QNSE procedure is extended to eliminate all turbulent scales, the resulting equations yield a spectral RANS (Reynolds-Averaged Navier-Stokes) model which presents a viable alternative to the widely popular today Reynolds stress models. Applied to turbulent flows with stable stratification, the QNSE theory yields such important results as the dispersion relation for internal waves in the presence of turbulence; the threshold criterion for internal wave generation; the demonstration of the absence of the critical Richardson number; the analytical derivation of the k-5/3 to k-3 spectral transition for the horizontal velocity, etc. The QNSE model has been used to derive K-l and K-e models that were tested in short-term and long-term simulations of the atmospheric boundary layers with moderate and strong stable stratification yielding a superior performance over conventional models. Presently, the QNSE model is being incorporated in the state-of-the-art atmospheric circulation model WRF (Weather Research and Forecasting) developed at the National Center for Atmospheric Research.
Finally, a three-dimensional, time-dependent circulation model of Blumberg and Mellor has been used in various studies of Tampa, Florida and Apalachicola Bays. An improved version of the model has been used to study a storm surge near the shores of Louisiana and Florida. In an ongoing effort, turbulence closure models employed in the circulation models are being improved using the QNSE methodology.
Selected Publications
Galperin, B., and S.A. Orszag, Eds. 1993. Large Eddy Simulation of Complex Engineering and Geophysical Flows. Cambridge University Press., 622 pp.
Sukoriansky, S., Galperin, B., and Chekhlov, A.: Large scale drag representation in simulations of two-dimensional turbulence, Physics of Fluids, 11, 3043–3053, 1999.
Galperin, B., Sukoriansky, S., and Huang, H.-P.: Universal n-5 spectrum of zonal flows on giant planets, Physics of Fluids, 13, 1545–1548, 2001. This publication is available in PDF format by clicking here.
Sukoriansky, S., Galperin, B., and Dikovskaya, N.: Universal spectrum of two-dimensional turbulence on a rotating sphere and some basic features of atmospheric circulation on giant planets, Physical Review Letters, 89, 124 501, 2002. This publication is available in PDF format by clicking here.
Galperin, B., H. Nakano, H-P. Huang, and S. Sukoriansky. The ubiquitous zonal jets in the atmospheres of gaint planets and Earth's oceans. Geophysical Research Letters, Vol. 31, L13303, doi:10.1029/2004GL01961. July 2004. This publication is available in PDF format by clicking here.
Galperin, B. and Sukoriansky, S. Energy spectra and zonal flows on the beta-plane, on a rotating sphere, and on giant planets, in Marine Turbulence: Theories, Observations, and Models, edited by H. Baumert, J. Simpson, and J. S¨undermann, pp. 472–493, Cambridge University Press, 2005.
Sukoriansky, S., Galperin, B., and Staroselsky, I.: A quasinormal scale elimination model of turbulent flows with stable stratification, Physics of Fluids, 17, 085 107–1–28, 2005.
Sukoriansky, S., Galperin, B., and Perov, V.: Application of a new spectral theory of stably stratified turbulence to atmospheric boundary layers over sea ice, Boundary-Layer Meteorology, 117, 231–257, 2005. This publication is available in PDF format by clicking here.
Sukoriansky, S., Galperin, B., and Perov, V.: A quasi-normal scale elimination model of turbulence and its application to stably stratified flows, Nonlinear Processes in Geophysics, 13, 9–22, 2006. This publication is available in PDF format by clicking here.
Galperin, B., Sukoriansky, S., Dikovskaya, N., Read, P.L., Yamazaki, Y.H., and Wordsworth, R: Anisotropic turbulence and zonal jets in rotating flows with a beta-effect, Nonlinear Processes in Geophysics, 13, 89-96, 2006. This publication is available in PDF format by clicking here.
Galperin, B., Sukoriansky, S., and Anderson, P.S., On the critical Richardson number in stably stratified turbulence, Atmospheric Science Letters, ASL.153, 2007.
