Ice observations
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The
hourly ice observations made from
the ship’s bridge during the ISPOL voyage contribute to a large international
program called the Antarctic Sea Ice Processes and
Climate (ASPeCt) program*. One of the objectives of ASPeCt has been to
compile sea ice observations collected from research vessels to Antarctica into
a standardised database for use by the scientific
community. The data have been contributed from numerous nations active
in the Antarctic, including Australia, Germany, the UK, US and Russia, and date
back to 1980. The original data from these voyages were in many different
formats (including some old analog charts), but in all cases we were able to
extract ice concentration and thickness information, and in many other cases
additional data on the
floe size, topography and snow cover were also available. Another outcome
of the project was the development of a standard protocol for new observations
and this has been followed for the observations aboard ISPOL. The data from ISPOL
will be the 85th voyage added to the database, which now comprises over 22,000
individual observations and
provides circumpolar sea ice data in all seasons.
The observations record
the concentration,
thickness, snow cover, floe size and topography of the
pack ice along the ship’s path. The topography data is used in a
simple model calculation of ridge topography to calculate the approximate contribution
of ridged ice to the overall thickness. An estimate of the characteristics
of the three “dominant” ice types at the time of the observation
provide information on the distribution of ice types and thickness within the
pack, as well as the nature of open
water areas.
The figures below show two
distinct sea ice
regimes along the transect from the ice edge to the ISPOL
floe. These areas are separated by an area of lower ice concentration between
approximately 40-45ºW. The thicker multi-year ice was found to the west
of 68S, 45ºW, which also had a
significantly thicker snow cover. At the time of each observation three
photographs were also taken (looking to port, ahead and starboard) and this html
document presents these images together with
the hourly data for each day. The data provide a quantified, if approximate,
account of ice conditions encountered along the ship’s track and may be
useful across many disciplines. Of course, the observations were also continued
after we left the ice station on 2nd
January, until we reached the ice edge.
Volunteers
from numerous scientific groups onboard ‘R/V Polarstern’ assisted
with the observations, which are available to all ISPOL participants
on the
intranet and via the AWI web site after the voyage. Additionally, the full
ASPeCt data set is available to the scientific community by contacting Dr Anthony
Worby at A.Worby@utas.edu.au.
Figures 1
and 2. Ice concentration and total ice thickness
(excluding the open water fraction) along the transect from the ice
edge to the ISPOL floe location.
*ASPeCt is a project within the Scientific
Committee on Antarctic Research (SCAR).
For further
information, or a copy of the CD-ROM “Observing Antarctic Sea Ice”,
contact: Dr Anthony
Worby, Australian Antarctic Division, Channel
Hwy, Kingston Tasmania 7050, Australia
for information about ice codes,
etc. please read THIS
Jan 2005
pages compiled by: Sascha Willmes, Uni Trier /
AWI
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