Airborne Geophysics
The
vast continent of Antarctica, separated from other landmasses by the
Southern Ocean and covered by ice, is one of the least known regions
of the world. Increasingly sophisticated technologies and
coordinated research programs are yielding new insights into
Antarctica's role in global climate and sea-level change. The
Institute for Geophysics (UTIG) is home to a group of investigators,
including
Donald Blankenship and
Jack Holt,
and a team of engineers and graduate students, who have been
developing and applying aerogeophysical techniques to address a wide
range of research topics in Antarctica since 1991.
Program History
UTIG's aerogeophysical program began in 1991 with a
project to develop the first integrated airborne platform to simultaneously
address problems in glaciology and subglacial geology. This initial research
grant (with the unwieldy acronym CASERTZ)
targeted understanding the influence of underlying geology on the location
and evolution of West Antarctic ice streams. Following the success of
that initial 50,000 line-kilometer survey, UTIG was asked by the National
Science Foundation to operate a facility (the Support Office for Aerogeophysical
Research; SOAR)
for conducting all U.S. aerogeophysics in Antarctica. In successive field
campaigns from 1994 until 2002, SOAR acquired and reduced 210,000 line
kilometers of aerogeophysical data from 425 research flights. These flights
supported 10 research projects with 20 investigators at 14 U.S. institutions.
Approximately 130,000 line kilometers of these data were collected for
research projects carried out by UTIG scientists in both East and West
Antarctica.
Instrumentation
For its aerogeophysical work in Antarctica, UTIG researchers use a ski-equipped,
DeHavilland Twin Otter aircraft fitted with the world's most powerful
ice-penetrating radar (see our profile over subglacial Lake Vostok below). Other
instruments simultaneously collect laser altimetry, gravity, and magnetic
data. This integrated geophysical instrumentation package is ideally suited
for glaciology and sub-ice geologic problems on sub-continental scales.
Basic data from the instrumentation suite consists of profiles of (a) ice thickness, (b) ice-surface elevation, (c) free-air gravity and (d) magnetic field intensity. Researchers are able to create two-dimensional images of geophysical and geomorphologic characteristics of the area surveyed from profiles collected over dense grids. These images allow them to define both critical ice-dynamic regimes and their underlying geologic provinces.
Basic data from the instrumentation suite consists of profiles of (a) ice thickness, (b) ice-surface elevation, (c) free-air gravity and (d) magnetic field intensity. Researchers are able to create two-dimensional images of geophysical and geomorphologic characteristics of the area surveyed from profiles collected over dense grids. These images allow them to define both critical ice-dynamic regimes and their underlying geologic provinces.
Current Research
Concerns about the potential impacts of global environmental
change are a principal motivation for glaciological research in West Antarctica.
From satellite remote sensing observations, we know that the Amundsen
Sea Embayment is the only major ice drainage basin in Antarctica that
is presently out of balance and contributing to global sea-level rise.
In some locations, it is thinning at rates of more than 10 meters per
year. In collaboration with researchers at the British Antarctic Survey,
UTIG researchers Holt and Blankenship have been funded by NSF
to conduct an 800x800x1100 kilometer survey of the entire Amundsen Sea
Embayment (labeled AGASEA
on the coverage map) of the West Antarctic ice sheet during 2004-2005.
UTIG's aerogeophysics group is also currently funded to develop new techniques for radar sounding, and testing these during further airborne and ground-based radar surveys in East and West Antarctica. These new techniques are used to investigate the development of water systems beneath the terrestrial ice sheets and will be applicable to studies of the Martian ice caps and of Jupiter's icy moon, Europa.
Future Plans
UTIG researchers are developing plans to migrate their
instrumentation and techniques to other aircraft and platforms for different
applications. One application is to execute large area surveys in East
Antarctica using long-range U.S. Navy aircraft. Another application under
study is the use of aerogeophysics to understand the link between mountain
uplift and glacier processes in Alaska and to help solve hydrologic problems
in Texas.
Relevance
Global climate change and it's consequences are an important topic of
scientific research and societal concern. The ice in polar regions plays
a crucial role on mediating and controlling global climate. Because of
the remoteness and scale of Antarctica, the role of the ice sheet in the
global climate system can only be properly understood through coordinated
research programs such as those conducted by scientists at UTIG.
Education and Training
The Antarctic research program at UTIG has provided
valuable research opportunities for many graduate and undergraduate students
as well as high school students who carry out summer internships at the
Institute each year as part of the Science
and Engineering Apprenticeship Program administered by the Applied
Research Laboratory at The University of Texas at Austin.
Opportunites for
participation: We are always open to
collaborating with new JSG students and postdocs that are interested in
working in the polar regions.
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