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"What Can Ocean Temperatures Tell Us about Climate in
the Southern Hemisphere?" and “Uncovering the Secrets
of Lake Vostok”
Guest Scientists: Martin Visbeck and
Michael Studinger
Martin Visbeck: Climate in the Southern Hemisphere
Martin Visbeck has joined us in all of our past
series to share his investigations about the climate
change. Previous programs have explored his
researches about the North Atlantic Oscillation and the
Hudson River. Today, he will discuss recent efforts to
understand changes in the oceans of the Southern
Hemisphere and the implications for understanding climate
patterns.
The Southern Ocean is the "other" region
where deep and bottom waters are
formed. Cold winds blowing of the Antarctic continent cool
the surface
waters until ice forms. As ice forms from sea water the
salt is left
behind making the water cold and salty which is the
perfect combination
to form very dense water. This dense water makes is way
via some
complicated interactions at the shelf break region into
the world ocean
and forms Antarctic Bottom Water (AABW). AABW can be found
in all major
ocean basins below the (better known) North Atlantic Deep
Water (NADW).
It returns to the surface near Antarctica after mixing
with the warmer
NADW. This other "grand ocean conveyor" is less well known
but might
circulate at an equal strength of about 10 Sv (1 Sv = 10^6
m^3/s) as the
lower NADW.
At Lamont we have begun monitoring the properties and amounts of
AABW
formed in the Weddell Sea and are exploring the
possibility to begin
instrumenting a second site to capture the waters leaving
the Ross
Sea.
Click
here for more about Martin's research.
Michael
Studinger: Lake Vostok
Buried under 4 km (2 1/2 miles) of ice in the heart of the
Antarctic continent
lies Lake Vostok, one of the world's biggest freshwater
lakes. For up
to 25 million years the Lake has been covered by an ice
sheet and
isolated from the atmosphere. In 1996 European satellite
imagery
confirmed the lake's existence, sparking scientific inquiry
into the Lake
and its processes. Lamont scientists are using
ice-penetrating radar
data, and GPS measurements to study the melting and
refreezing in the lake, and the direction of ice flow of
the overlying glacier to
understand better the dynamics of the water exchange system. The
geologic
origin of the lake provide important boundary conditions
for the
ecosystem. The magnetic and gravity field of the Earth are
used to
interpret the geologic structures beneath the ice sheet.
Here are selected links to related LDEO research projects:
http://www.ldeo.columbia.edu/~mstuding/
http://www.ldeo.columbia.edu/~mstuding/vostok
http://www.earthinstitute.columbia.edu/news/vostok/vostok.swf
http://www.earthinstitute.columbia.edu/news/story3_2_01.html
http://www.earthinstitute.columbia.edu/news/2003/story01-21-03.html
 
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