International Polar Year 2007–2008 - WMO

Fig. 2.3-14. Laser
altimeter swath over
Antarctic fast ice (and
grounded icebergs)
during the IPY SIPEX
experiment, showing
freeboard height (the
height of the ice or
snow surface above
sea level).
(Graph: J. Lieser)
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IPY 20 07–20 08
and resolution of data between highly localised in situ
measurements and coarser resolution satellite data.
The work conducted during IPY will be crucial for the
calibration and validation of new satellite sensors, such
as the radar altimeter aboard CryoSat-2 which came
online during 2010.
Turner et al., (2009a) analysed sea ice patterns in
relation to climate parameters to show that the growth
in Antarctic sea ice extent, by around 1% per decade
since the late 1970s, seemed to be controlled by a 15%
increase in the strength of circumpolar winds, which
were in turn driven by winds propagating down to
the surface from the polar vortex around the ozone
hole in summer and autumn. The stronger winds also
accentuate the Amundsen Sea Low, which brings
warm air south down the Antarctic Peninsula, melting
or delaying the onset of sea ice there. These winds
then pass over West Antarctica cooling as they go, to
emerge cold over the Ross Sea where they cause sea
ice to grow. The decrease in sea ice in the one area is
more or less balanced by the increase in the other area.
Summary and Legacy
During IPY, the Southern Ocean was measured
in a truly comprehensive way for the first time. IPY
measurements spanned the circumpolar extent of
the Southern Ocean, from the subtropical front to the
Antarctic continental shelf. Many measurements (e.g.
Argo, marine mammal tags and moored time-series)
covered the full annual cycle. New technologies
allowed many characteristics of the Southern Ocean
to be measured for the first time, including ocean
currents and properties beneath the sea ice, trace
metal concentrations throughout the full ocean depth
and the discovery of many new species. Perhaps most
importantly, the IPY activities spanned all disciplines
of Southern Ocean science, providing the integrated
observations that are essential to address questions of
high relevance to society, including climate change,
ocean acidification and the future of the Southern
Ocean ecosystem. The multi-disciplinary view of the
state of the Southern Ocean obtained during IPY
provides a benchmark against which past and future
measurements can be compared to assess rates of
change. This achievement was the result of the work
of hundreds of scientists from numerous nations.
IPY aimed to determine the present environmental
status of the polar regions; to understand past and
present change in the polar regions; to advance our
understanding of polar-global teleconnections; and
to investigate the unknowns at the frontiers of science