Theoretic Studies in Geophysical Fluid Dynamics and Climate Dynamics

Indiana University, Bloomington IN

Investigators

Abstract

Wang DMS-0908051 This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The investigator studies factors that are relevant to the low-frequency variability of atmospheric and oceanic flows and that play a role in climate changes. He focuses on three sources of atmospheric and oceanic variability: the wind-driven ocean circulation, the thermohaline circulation, and the El Nino Southern Oscillations (ENSO). The study involves, on the one hand, applications of existing mathematical theory to the understanding of the underlying problems, and, on the other hand, the further development of new mathematical theories -- dynamic transition theory, geometric theory for incompressible flows, and attractor bifurcation theory -- that are applied to the physical problems. These new theories also have application to other problems in nonlinear science and engineering. The main idea of dynamic transition theory is to search for the full set of transition states, giving a complete characterization of stability and transition. The set of transition states -- physical "reality" -- is represented by a local attractor. Following this line, dynamic transition theory is developed to identify the transition states and to classify them both dynamically and physically. The project involves specific collaborations with atmosphere/ocean scientists in different institutions and includes training of graduate students. The investigator studies some typical sources of climate variability, which, independently and interactively, play a significant role in climate changes. Wind-driven circulation plays a role mostly in the oceans' subannual-to-interannual variability, the El Nino Southern Oscillations are associated with interannual variability, and the thermohaline circulation is most important in decadal-to-millenial variability. The investigator undertakes a careful fundamental-level examination of these phenomena. Graduate students are involved in the project. The studies could lead to improved predictions of and new insights into weather, climate, and environmental phenomena of central importance to our economy.