Over the last decade, several hundred seals have been
equipped with conductivity-temperature-depth sensors in
the Southern Ocean for both biological and physical
oceanographic studies. A calibrated collection of seal-derived
hydrographic data is now available, consisting of more
than 165,000 profiles. The value of these hydrographic
data within the existing Southern Ocean observing
system is demonstrated herein by conducting two state
estimation experiments, differing only in the use or not of
seal data to constrain the system. Including seal-derived
data substantially modifies the estimated surface mixedlayer
properties and circulation patterns within and south of
the Antarctic Circumpolar Current. Agreement with
independent satellite observations of sea ice concentration
is improved, especially along the East Antarctic shelf.
Instrumented animals efficiently reduce a critical observational
gap, and their contribution to monitoring polar climate
variability will continue to grow as data accuracy and
spatial coverage increase.
