Rothera Time Series (RaTS) Southern Ocean Latitude:   -67.5800     Longitude:   -68.1750 Associated Investigators: Hugh Venables , Alexander Brearley ,   Andrew Clarke ,   Michael Meredith   Related Web Sites: [www.bas.ac.uk/project/rats/]   The western Antarctic Peninsula (WAP) warmed more rapidly than any other region in the Southern Hemisphere during the second half of the 20th century. To understand the impacts of this change on the interdisciplinary marine environment, the Rothera Time Series (RaTS) was instigated in 1997, to make the high-quality, sustained ocean measurements required. RaTS involves quasi-weekly profiling of the physical properties (temperature, salinity, density) of the water column at the WAP from rigid inflatable boats, plus sampling for a range of biogeochemical and biological parameters. The suite of measurements includes chlorophyll concentration, nutrients, isotopic tracers of ice melt, carbonate system parameters, and so on. Uniquely, RaTS includes full winter-time ocean measurements, including sampling though holes cut in sea ice when the ocean surface is completely frozen; these winter measurements have enabled some of the most important new insights into the functioning of the oceanographic and biological systems to be obtained.