3.3. The Southern Ocean Basin.

Dr Kevin Speer provided an overview of the key observational activities in the Southern Ocean. For the full report see appendix 3.3. Dr Speer highlighted some key high latitude observational challenges, such as obtaining observations in the sea ice zone. This is an area where Argo cannot operate, but floats are being developed which can operate under ice, and moored buoys with sound sources can be used for acoustic tracking of floats. Moorings that attach to the ice are also being developed. The challenges associated with observing processes in this region, and the complexity of processes themselves (for instance the atmosphere/ocean/ice boundary layers) mean that fundamental improvements could be made in surface fluxes and reanalysis products. Dr Speer advocated a Southern Ocean regional reanalysis. Higher spatial resolution is needed, particularly around the ice edge in models. The GSOP panel will be developing global reanalyses first, but may spin up regional high-resolution activities in collaboration with basin panels. A group lead by Dr John Calder at NOAA already planning an Arctic regional reanalysis, and many groups are undertaking such regional activities. These groups have begun to interact and further discussion is expected this summer at the CLIVAR Southern Ocean Panel meeting. Dr Speer suggested that enhancements to observations in the Southern Ocean should be a priority, specifically for sea ice, surface meteorology, drifters, transport arrays and XBT's. Planning for the International Polar Year is well underway, and this could be an opportunity to push for these enhanced measurements. The costs of observations in the Southern Ocean were discussed, in particular the acoustic tracking system for floats, and the difficulty in justifying such an expensive system. However, it was argued that observations are poor in this region; estimates of circulation and hence heat and freshwater transports cannot be obtained from the usual thermal wind methods since barotropic flows are so strong. An investment in observations is needed to determine whether the additional measurements are needed.