Abstract

The Rothera times series (RaTS) has been collecting water column profiles from Ryder Bay through the year since 1998. During this time there has been considerable variation in winter ice cover, providing an opportunity to study the potential sub-surface effects of the broad scale reduction in ice cover along the Antarctic Peninsula. In heavy ice years there is little mixing in winter, extending to approximately 75m. In low ice years winter mixing can reach 150m, releasing significant amounts of heat to the atmosphere. This mixing homogenises salinity and so leads to reduced water column stratification the following summer. This reduced stratification leads to an increase in the vertical extent of mixing and so allows heat to be mixed from the surface to greater depths (for the same mechanical and heat energy input). By early autumn temperatures recover to initial values at around 100m; deeper than 100m temperatures don’t fully recover but shallower than 100m they increase to warmer than they started. This process increases the heat content of the water column in autumn and therefore likely affects the formation of ice the following winter.