I am a Postdoc studying physical oceanography at the Department of atmospheric and oceanic sciences, UCLA in Jim McWilliams 's lab. My research interests are geophysical fluid dynamics, energetics of stratified turbulent flows and the interactions between mesoscales, sub-mesoscales and internal waves in the ocean. I obtained my PhD at the Scripps Institution of Oceanography, UCSD. My thesis advisors were Kraig Winters and Stefan Llewellyn Smith.
Department of Atmospheric and Oceanic Sciences.
3637 Geology Building, UCLA,
Los Angeles, California, USA
Senior Lecturer (Assistant Professor)
Porter School of the Environment and Earth Sciences.
311 Kaplun Building, Tel Aviv University, Ramat Aviv, Israel
I study the physics of the ocean circulation using a combination of mathematical theory, numerical models, and analysis of in situ measurements. In particular, I am interested in the oceanic processes that determine the transfer of energy, heat, and other tracers across scales, and from the surface to the ocean interior. These processes have fundamental implications to the climate system, to the dispersion of contaminants, and to Biology. One of my main research foci is to understand the dynamics of submesoscale currents; recently discovered flow patterns, consisting of rapidly evolving fronts, filaments, and eddies. Submesoscale currents can interact with both the larger-scale currents and eddies, and the smaller-scales internal and surface waves, thereby affecting a wide range of physical phenomena.
Oceanic Energy Pathways
Oceanic mesoscale eddies, with spatial scales of O(100km) and time scale of O(weeks-month), are the largest reservoir of kinetic energy in the oceans. They are considered to be balanced in the sense that their dynamics is largely constrained by the Earth's rotation and by the stratification of the oceans. As a result they are expected, according to geostrophic turbulence theory, to transfer kinetic energy to larger scales. However, observations show that the oceanic kinetic energy is dissipated at molecular scales. Some mechanism must therefore break the balanced dynamics of the mesoscale eddies, and allow kinetic energy to be transferred to smaller scales where it can be dissipated. In 7 we show how the spontaneous formation of submesoscale currents can break the balance (spontaneous imbalance), and in 9 we show how near-inertial internal waves can interact with mesoscale and submsoscale currents and stimulate the loss of balance (stimulated imbalance).
Submesoscale Turbulence and Frontogenesis
Submesoscale turbulence consists of flow structures with spatial scales of O(100m-10km), temporal scales of O(hours-day), in a dynamical regime characterized by O(1) Rossby and Richardson numbers. Phenomenologically, the flow exhibits anisotropic patterns of lines or streaks with large magnitudes of buoyancy and velocity gradients, cyclonic vorticity and convergence (10,11,12). The associated velocity spectrum is shallow and the velocity gradient spectrum has roughly equal contributions from the divergence and vorticity spectra that comprise it. In 15 we use these dynamical, phenomenological, and spectral characteristics to develop an asymptotic theory for submesoscale turbulence. Specifically, we characterize the formation of the fronts and filaments, which we define as submesoscale frontogenesis. We are able to validate the theory with high-resolution numerical simulations and Lagrangian in-situ measurements. Our theory has important implications to the horizontal and vertical transport of tracers in the ocean.
Dispersion of Oil and other Contaminants
Oil spills are unfortunately common in today's world. I am actively involved in the Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE), which is a team dedicated to predicting the fate of oil released into our environment. I took part in a number of field experiments and numerical studies in the Gulf of Mexico, near the site of the catastrophic DeepWater Horizon oil spill. In 11,12,13 we investigate and characterize the important role of submesoscale eddies and fronts in governing oil dispersion in the region.
Eddy-Inertial Wave Interaction
(Near) Inertial Waves (NIWs) are internal waves most typically excited by high frequency wind variability (e.g., storms). The mechanisms by which the excited NIWs propagate into the ocean interior, reduce in size, break, and vertically mix properties remain poorly understood. Possible mechanisms include the interactions with the coexisting mesoscale eddies and submesoscale currents. In 9 we demonstrate that as NIWs propagate through a field of fronts and eddies they scatter into smaller scales while actively exchanging energy. These interactions are found crucial to match observed energy spectra at sub- and super-inertial frequencies, and to enhance the forward cascade of mesoscale energy to dissipation.
IN PROGRESS / SUBMITTED
Barkan, R., and J. C. McWilliams, and K. Srinivasan, and M. J. Molemaker, and E. A. D'Asaro. 2019. The Role of Horizontal Divergence in Submesoscale Frontogenesis. J. Phys. Oceanogr. Under review.
Bracco, A., and Daoxun, and R. Barkan, and M. Berta, and J. Choi, and Guanpeng, and A. Berta, and J. C. McWilliams, 2019. Diurnal Cycling of Submesoscale Dynamics: Lagrangian Implications. J. Phys. Oceanogr. Under review.
IN PRESS / PUBLISHED
Palmer, J., and B. Fox-Kemper, and R. Barkan, and J. Choi, and A. Bracco, and J. C. McWilliams. 2019. Impacts of convergence on Lagrangian statistics in the Gulf of Mexico. J. Phys. Oceanogr. In Press.
Srinivasan, K., and J. C. McWilliams, and M. J. Molemaker, and R. Barkan. 2019. Submesoscale Vortical Wakes in the Lee of Topography. J. Phys. Oceanogr. In Press.
D’Asaro, E. A., and A. Y. Shcherbina, and J. M. Klymak, and M. J. Molemaker, and G. Novelli, and C. M. Guigand, and A. C. Haza, and B. K. Haus, and E. H. Ryan, and G. A. Jacobs, and H. S. Huntley, and N. J. M. Laxague, and S. Chen, and F. Judt, and J. C. McWilliams, and R. Barkan, and A. D. Kirwan, and A. C. Poje, and T. M. Özgökmen, 2018. Ocean convergence and the dispersion of flotsam. Proc. Nat. Academy Sci., 201718453. LINK
Barkan, R and J. C. McWilliams, and A. F. Shchepetkin, and M. J. Molemaker, and L. Renault, and A. Bracco, and J. Choi. 2017. Submesoscale Dynamics in the Northern Gulf of Mexico. Part I: Regional and Seasonal Characterization, and the Role of River Outflow. J. Phys. Oceanogr. 47, 2325-2346. LINK
Choi. J., and A. Bracco, and R. Barkan, and J. C. McWilliams. 2017. Submesoscale Dynamics in the Northern Gulf of Mexico. Part III: Lagrangian Implications. J. Phys. Oceangr. 47, 2361-2376. LINK
Barkan, R and J. C. McWilliams, and A. F. Shchepetkin, and M. J. Molemaker, and K. Srinivasan, and A. Bracco, and J. Choi . 2017. Submesoscale Dynamics in the Northern Gulf of Mexico. Part II: Temperature-Salinity Compensation, and Cross Shelf Transport Processes. J. Phys. Oceangr. 47, 2347-2360. LINK
Barkan, R., Winters, K.B. and McWilliams, J.C. 2017. Stimulated Imbalance and the Enhancement of Eddy Kinetic Energy Dissipation by Internal Waves. J. Phys. Oceangr. 47, 181-198. LINK
Pratt, L., and R. Barkan, and I. Rypina. 2016. Scalar flux kinematics. Fluids. 1.3: 27. LINK
Barkan, R., Winters, K.B. and Lewellyn-Smith, S.G. 2015. Energy Cascades and Loss of Balance in a Re-entrant Channel Forced by Wind Stress and Buoyancy Fluxes. J. Phys. Oceangr. 45, 272-293. LINK
Barkan, R., Winters, K.B. and Lewellyn-Smith, S.G. 2013. Rotating Horizontal Convection. J. Fluid Mech. 723, 556-586. LINK
Winters, K. B. and Barkan, R. 2013. Available potential energy density for Boussinesq fluid flow. J. Fluid Mech. 714, 476-488. LINK
Barkan, R., and ten Brink, U. 2010. Tsunami simulations of the 1867 Virgin Islands earthquake: Constraints on epicenter location and fault parameters. Bulletin of Seismological Society of America. 100, 995-1009. LINK
Zvuloni, A., Artzy, Y.,Stone, L., Kramarsky, E., Barkan, R., Kushmaro, A., Loya, Y. 2009. Spatio- Temporal transmission patterns of Black-Band Disease in a coral community. PLoSONE 4, 1-10. LINK
ten Brink, U., Barkan, R., Andrews, B.D., and Chaytor, J.D. 2009. Size distribution and failure initiation of submarine landslides and subaerial landslides. Earth and Planetary Science Letts. 287, 31-42. LINK
Barkan, R. , ten Brink, U., and Lin, J. 2009. Far field tsunami simulations of the 1755 Lisbon earthquake: Implications for tsunami hazard to the U.S East Coast and the Caribbean. J. Marine Geology. 264, 109-122. LINK
I am looking for graduate students and postdocs, please contact me if interested