Organization and sensitivity of the Antarctic Circumpolar Current
Department of Physics, National and Kapodistrian University of Athens
It has been recently argued that the regulator of the Earth climate may lie in the southern seas, where between the continents of the South and Antarctica, flows the strongest ocean current on Earth, the Antarctic Circumpolar Current (ACC). However, the ACC remains poorly understood, as small-scale eddies, which are not captured by climate models, determine its properties. Therefore, we need a comprehensive theory of the ACC climatology that will clarify its dynamics and will enable its accurate modeling.
This study utilized novel theoretical results and constructed a simplified, yet realistic, model of the ACC dynamics that enables the comprehensive investigation of the ACC climatology and its dependence on external parameters.
The study concluded that there are two climate states of the ACC. In the first the structure of the ACC is principally determined by the mean atmospheric forcing, while the principal determinant of the ACC structure in the second state are the small scale eddies supported by the current. For given external parameters the climate states were shown to be unique. If there were multiple climate states the ACC could, under the same external conditions, transit from one state to the other and induce itself abrupt climate change. The uniqueness of the states excludes this possibility. The main parameter that determines the climate state was found to be the variability in the atmospheric wind stress, which is not included in current climate models. A main conclusion of the study is that wind gustiness should be included in future models in order to obtain realistic assessment of the climatic impact of the ACC.
Coordinator: Petros Ioannou, Associate Professor, Department of Physics, National and Kapodistrian University of Athens
Nikolaos Bakas, Post-doctoral researcher, Department of Physics, National and Kapodistrian University of Athens
Navid Constantinou, Doctoral Student, Department of Physics, National and Kapodistrian University of Athens