Final Report Summary - WEDDEL (Wind-driven upwelling and eddy transports in the Southern Ocean - a model intercomparison in three dimensions)
The Southern Ocean has a strong influence on the global climate. Significant percentages of the global oceanic uptake from the atmosphere of heat and carbon are directly associated with the circulation in the Southern Ocean. For this reason it is important to assess how it is represented the current class of climate models. WEDDEL has compared the 25 global coupled climate models (GCMs) that participated in the Coupled Model Intercomparison Project Phase 3 (CMIP3) that was part of the IPCC AR4 (IPCC, 2007) in this respect. During the work on the project three distinct work fields emerged.
First, it was investigated why the strength of the Antarctic Circumpolar Current (ACC) varies so strongly across the control runs of the AR4 climate models (see sec. 2.1). Second, WEDDEL contributed to an assessment of the 21st century climate model scenarios with respect to future changes of the ACC (sec. 2.2). The projected ACC changes vary widely and don't even agree on the sign of the changes. Both these work fields identified the crucial role of eddy-induced transports for the large-scale circulation of the Southern Ocean. Unfortunately these could not be directly analysed because the respective data are generally unavailable. However, for WEDDEL's third work field the parametrized eddy-induced transports for one climate model are compared in detail with an eddy-permitting ocean model (sec. 2.3).
First, it was investigated why the strength of the Antarctic Circumpolar Current (ACC) varies so strongly across the control runs of the AR4 climate models (see sec. 2.1). Second, WEDDEL contributed to an assessment of the 21st century climate model scenarios with respect to future changes of the ACC (sec. 2.2). The projected ACC changes vary widely and don't even agree on the sign of the changes. Both these work fields identified the crucial role of eddy-induced transports for the large-scale circulation of the Southern Ocean. Unfortunately these could not be directly analysed because the respective data are generally unavailable. However, for WEDDEL's third work field the parametrized eddy-induced transports for one climate model are compared in detail with an eddy-permitting ocean model (sec. 2.3).
