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Research

Research diversity and interdisciplinary focus are the development principles that have driven the creation and growth of the Center. Accordingly, the topics under research by our faculty cover a wide spectrum, particularly for our size. This model of faculty composition stands in contrast to more traditional AOS departments -- we cannot boast great strength in any one particular area beyond the high quality of the research an individual faculty member contributes to that area. The strength of this model is that it maximizes our potential interactions with applied mathematics, and graduate students have a wide choice of research topics from which to choose. A sampling of our research follows (in most cases, more information can be found on individual faculty homepages).

buhler_research_fig.jpg Oliver Bühler works on fundamental topics in wave mean-flow/vortex interaction. For example, he and a collaborator have recently uncovered a mechanism by which a wave-vortex interaction can cause a persistent, cumulative change in the mean state in the absence of dissipation or breaking (Buhler and McIntyre 2003). Such an effect brings into question fundamental parameterizations of gravity waves used in atmospheric models. Buhler also works on coastal vortex dynamics, statistical mechanics, and stratospheric transport.

ch_b_w_25.jpgStephen Childress has been active for many years in developing theoretical models of mixing, diffusion, and dynamo action in weakly diffusive systems, and has recently published (Childress and Gilbert 1995) a monograph dealing with fast dynamo theory. More recent research has dealt with convection in systems that break the symmetry of the classical Boussinesq theory, including the calculation of shifted mean temperature in fully developed convection in a fluid with temperature-dependent viscosity. Other work has dealt with the estimation of dissipation in forced Navier-Stokes flows (Childress et al. 2001).

epg_research_fig.jpgEdwin Gerber investigates the internal variability of the atmosphere and its relation to climate change.  He has developed a hierarchy of idealized models to understand the spatial and temporal structure of intraseasonal variability in the mid and high latitudes, in particular the North Atlantic Oscillation and annular mode patterns of variability (e.g. Gerber and Vallis 2005,  2007).  His recent research addresses coupling between the stratosphere and troposphere, with focus on the influence of stratospheric sudden warmings on the troposphere (Gerber and Polvani, 2008).  He works on the use (and verification) of numerical models and stochastic techniques to understand fundamental atmospheric processes and climate change predictions.

coverpiece_a.JPGDavid Holland's research focuses on polar oceanography and ice dynamics and has led to improved techniques for coupling sea and ocean models. Holland recently showed that the Weddell Polynya results from interactions between topographically generated eddies and surface ice (Holland 2001). He has recently conducted some of the first simulations in which floating ice shelves are included in an ocean general circulation model. Along with Professor Tabak, he is designing a series of rotating tank experiments to investigate dense overflows from high latitude, shallow seas. 

toggle_elnino_rk.gifRichard Kleeman uses dynamical systems analysis tools such as information theory of predictability. This is then applied to dynamical models of relevance to the atmosphere and ocean. A major result obtained recently is a new explanation for how and why the usefulness of prediction can vary from one forecast to another. In the past decade he has also helped develop a new theory to explain the irregularity of El Nino using stochastic systems theory. He has also been responsible for the development of a leading theory explaining decadal fluctuations in this phenomenon.

Andrew Majda has achieved high distinction over the past 25 years in many branches of applied mathematics, and especially in the area of turbulence research (for example, Majda and Kramer 1999). In recent years he has applied his insights to the study of the climate system. He and his collaborators have made important contributions to tropical meteorology (Majda and Biello 2004), stochastic parameterizations for climate research (Majda, Timofeyev and Vanden-Eijnden 2003) and applications of statistical mechanics to large-scale geophysical flows (Turkington et al. 2001).

Olivier Pauluis research is an expert on climate sciences, and particularly on the interactions between moist convection and the atmospheric circulations. His research interests include the feedbacks between large-scale circulation and precipitation (Pauluis 2004), the role of water vapor and moist processes on the maintenance of the atmospheric circulation (Pauluis and Held 2002, Pauluis 2006), the development of high-resolution numerical models to simulate convective systems in the tropics (Pauluis and Garner 2006), and theoretical multi-scale models for the atmosphere (Frierson et al. 2004, Pauluis et al. 2007).

topex_sshanom_sm.jpgShafer Smith has made theoretical contributions to the interpretation of observed sea surface variability patterns, understanding the magnitude and vertical structure of large-scale oceanic turbulence (Smith and Vallis 2002) and to prediction for the mixing of both dynamic and passive tracers in a range of geophysical flows (Smith et al. 2002). Smith is currently working on applying these ideas to improve the parameterization of unresolved baroclinic mixing in numerical climate models.

Esteban Tabak has developed during the last few years reduced models that shed light on various aspects of the global circulation. He has made significant contributions to the field of dispersive wave turbulence (Lvov, Polzin and Tabak 2004), which may ultimately explain the origin of the Munk-Garret spectrum of internal waves in the ocean. He is currently working on new models for well--mixed layers in the atmosphere and ocean, on sea--ice dynamics, and on improving our understanding of various processes involved in shelve-slope exchange that are poorly parameterized in present day GCMs.