Global research in sea and sky

Polarstern sets off for the Antarctic
On Wednesday, 22nd October, 2003, the research ice-breaker of the Alfred
Wegener Institute for Polar and Marine Research (AWI) - Polarstern -
will depart on her 21st Antarctic expedition. Studies of the decay of
the ozone layer and of communities on the Southern Ocean sea floor are
planned.

Across the globe
The first cruise leg will take thirty scientists and forty crew members
to Cape Town, South Africa. On this 6500 nautical mile journey, the
ship will traverse large portions of the northern and southern
hemispheres via the Atlantic Ocean.
This presents the opportunity of gathering important data from both
hemispheres regarding the distribution of atmospheric trace elements. A
focal point of the study are so called organohaline compounds, which
play an important role in the the breakdown of ozone. The stratospheric
ozone layer will be monitored daily from the ship using ozone sondes
which climb to an altitude of 30 kilometres. UV radiation incident at
the earth's surface will also be monitored. The aim is to study the
decay of stratospheric ozone and the resulting increase in UV radiation
reaching the earth's surface. In order to research the effects of
aerosols on climate, a laser system will be used to observe cirrus
clouds and, along the west African coast, the distribution of Saharan
dust in the troposphere. Other measurement systems on board will
validate instruments carried by the earth observation satellite ENVISAT
which also measure trace gases. The first cruise leg will end on 15th
November, 2003, in Cape Town.

To Antarctica
Sixty scientists will be aboard when Polarstern departs Cape Town for
Antarctica on 17th November. An important part of this journey will be
to bring supplies to the Antarctic stations Neumayer and Kohnen.
Materials, supplies and Christmas parcels for the overwinters, who have
been working at Neumayer since February, have already been loaded onto
the ship in Bremerhaven. Polarstern should have reached the Atka Bight
by Neumayer and, if the ice allows, been unloaded, by the end of
November.
The scientific work on this cruise leg will concentrate on the
ecosystems of the Antarctic continental shelf. The term 'shelf' refers
to the shallow portion of the ocean, close to the coast. Diverse
communities reminiscent of coral reefs but including sponges, crabs,
worms, starfish and fish can be found here. The giant icebergs of the
Antarctic, with drafts of up to three hundred metres, are a constant
danger for life in these shallow waters. A stranded iceberg acts like a
bulldozer, destroying large areas of the sea floor. The constant change
between destruction and recolonisation says much about the sensitivity
and regenerative strength of polar ecosystems.
With the aid of satellites as well as the ship's radar and helicopter
flights, drifting and stranding of icebergs and changes in the shelf-ice
edge will be observed. In order to better understand the process of
recolonisation, an experiment to mimic the destruction caused by a
stranded iceberg is planned. The community of a predefined area of a
few hundred square metres will first be thoroughly mapped, then, in a
controlled manner, destroyed using drag-nets. The subsequent
development of fauna will be monitored every two years on future
expeditions. This should reveal the time scales and mechanisms of
recolonisation. When these processes are understood, says AWI biologist
Dr Thomas Brey, we can predict the reaction of polar ecosystems to
climate change.

On 18th January, 2004, Polarstern will return to Cape Town. Two further
cruise legs will take her back into Antarctic waters before the return
to the north: On 2nd June 2004 Polarstern will return to Bremerhaven.

Bremerhaven, 17.10.03