Temporal Variability in the Antarctic Polar Front (2002-2014)

The Antarctic Polar Front (PF) is an important biogeochemical divide in the Southern Ocean, associated with large-scale gradients in temperature, nutrients, and distinct biological communities. Physical and biogeochemical studies of the Southern Ocean can benefit from knowledge of the PF location and its temporal variability, as changes in the location of the PF could cause changes in the eddy field or in biological productivity and biogeography. Our current understanding of PF variability is limited, as most studies have identified climatological frontal positions using sparsely-sampled hydrographic data or satellite data largely affected by cloud cover. Here, we use SST observations from cloud-penetrating microwave radiometers to map the PF from SST gradient maxima, yielding a continuous PF time series from 2002 to 2014 at daily and weekly resolution. We investigate intra-annual to interannual variability in the PF position and its relationship with climate indices to better understand the drivers of variability. We find a significant southward shift in the zonal mean PF position, consistent with studies that predict the ACC system to mirror the poleward intensifying westerly winds.