  The frontal structure of the Southern Ocean is investigated using a
sophisticated frontal detection methodology, the Wavelet/Higher Order
Statistics Enhancement (WHOSE) method, introduced in \cite{Chapman2014}. This
methodology is applied to 21 years of daily gridded sea-surface height (SSH)
data to obtain daily maps of the locations of the fronts. By forming
`heat-maps' of the frontal occurrence frequency and then approximating these
heat-maps by a superposition of simple functions, the time-mean locations of
the fronts, as well as a measure of their capacity to meander, are obtained and
related to the frontal locations found by previous studies.
  The spatial and temporal variability of the frontal structure is then
considered. The number of fronts is found to be highly variable throughout the
Southern Ocean, increasing (`splitting') downstream of large bathymetric
features and decreasing (`merging') in regions where the fronts are tightly
controlled by the underlying topography. In contrast, frontal meandering
remains relatively constant. Contrary to many previous studies, little no
southward migration of the fronts over the 1993-2014 time period is found, and
there is only weak sensitivity to atmospheric forcing related to SAM or ENSO.
The reasons for the discrepancy between this study and previous studies using
contour methods are investigated and it is shown that the spatial variability
of the frontal structure is not tied to the underlying sea-surface height. It
is argued that the results of studies using sea-surface height contours to
define front must be interpreted with care.

Atmospheric and Oceanic Physics