Funding
We gratefully acknowledge the Antartic Glaciology and Antarctic
Meterology sections, Office of Polar Programs, of the United States
National Science Foundation for support of this work.
NSF Grants
Supporting this work:
1) NSF Award # 9904947 Antarctic Glaciology
Stable Isotope Studies at West Antarctic ITASE Sites
This
collaborative proposal supports a project to perform stable isotope
analyses of samples collected along the International Trans-Antarctic
Scientific Expedition (ITASE) traverses which will begin during the
1999/2000 Antarctic field season. This work will focus on the spatial and
temporal distribution of oxygen-18 and deuterium in West Antarctica (where
data are particularly sparse) and the calibration of the isotope-climate
relationship on a site-by-site basis, using instrumental and
remote-sensing temperature histories. Specific objectives of this work
which contribute to ITASE are: 1) to obtain detailed oxygen-18, deuterium
and deuterium excess and stratigraphic histories in snowpits at most or
all of the ITASE coring sites; 2) to provide direct calibration of the
isotope-climate relationship at each site through a combination of direct
(AWS) and indirect (passive microwave satellite) temperature measurements;
3) to obtain isotope profiles covering the last 200 years; and 4) to use
the results to provide 200-year climate histories at high temporal and
broad spatial resolution across West Antarctica that will allow testing of
proposed relationships among isotopes, moisture source conditions,
synoptic scale climatology, and site-specific meteorological parameters,
and which will enhance our ability to interpret isotope records from older
and deeper Antarctic ice cores
2) NSF Award # 0229416 Antarctic Glaciology
Temperature Variability of the Last 1000 years in East Antarctica
This award supports a pilot ice-core drilling and analysis program to
test
the feasibility of obtaining well-dated, high-resolution isotope and
chemistry records from East Antarctica. Shallow ice cores will be obtained
from two locations: 1) ~100 from South Pole towards North Victoria Land,
as an extension of the Byrd Station-to-South Pole ITASE traverse
[International Trans Antarctic Scientific Expedition]; 2) at Taylor Dome,
near the original deep coring site. Each of these cores will be sampled at
very high resolution (~1/2 cm) and analyzed for stable isotope (delta D or
delta 18-O) at the University of Washington. The cores will also be
analyzed for trace ions at the University of Maine, under separate
funding. The resulting time series, if they can be well dated as we
expect, will be used to calibrate against the instrumental temperature
record, brightness temperature observations from satellites and
operational weather forecast reanalysis data sets. Results from this
calibration work will be used to help plan a program of larger scope, with
the objective of mapping the spatial expression of climate variability in
East Antarctica. A summary document will be produced and made available to
the community to help with planning of related field programs (e.g. deep
ice radar, firn radar profiling, atmospheric chemistry, ice coring, snow
surface properties for satellite observations, ice surface elevation and
mass balance).
3) NSF Award #0126161 Antarctic Meterology and Climatology
Remote Observations of Ice Sheet Surface
Temperature: Toward Multi-Proxy Reconstruction of Antarctic Climate
Variability
This project will develop spatially extended and statistically reliable
estimates of Antarctic surface temperature variations over the past
several centuries, using a multi-proxy calibration/verification approach
that combines the climate signal in ice core, satellite remote sensing,
and weather station data. Antarctica has been problematic from the point
of view of large-scale paleoclimate reconstruction because of the paucity
of long-term instrumental data, and the relatively low resolution of most
ice cores. Several new developments, particularly the network of shallow
(~100 meter) ice cores from the ongoing International Trans-Antarctic
Scientific Expedition (ITASE) project will yield broad spatial coverage of
annually resolved ice core physical properties, chemistry, and stable
isotope data over more than a hundred years. Second, there are now over
twenty years of microwave and infrared brightness temperatures available
from satellites covering virtually all of Antarctica with seasonally
resolved information that has been demonstrated to record the ice
surface/near surface temperature with very reasonable precision and
accuracy. Finally, higher quality microwave emission data from Advanced
Microwave Scanning Radiometers (AMSR) with much finer spatial resolution
and radiometric fidelity than those from previous sources will offer an
improved view of longer term mean temperatures in Antarctica. The 40-year
instrumental record and the shorter but spatially more comprehensive
Automatic Weather Station network will be combined with
seasonally-resolved 37-gigahertz satellite-based ice surface temperature
estimates to reconstruct Antarctic-wide temperature patterns during the
past forty years. The sparser Antarctic instrumental surface temperature
data available back nearly to the beginning of the century will be added
for longer-term, though quite spatially-restricted, cross-validation of
these reconstructions. This cross-validation procedure has been used
successfully with roughly century-long instrumental records at locations
primarily in the Northern Hemisphere. The longer time scale will be
approached through a cross-validation of the proxy-based pre-20th century
surface temperature reconstructions using information on thermal emission
from deeper in the firn that is contained in low-frequency passive
microwave satellite measurements.
4) NSF Award Pending Antarctic Glaciology
Stable Isotope Studies at East Antarctic ITASE Sites
This award supports a project to obtain stable isotope profiles from
shallow (<100 m) ice cores from East Antarctica, to add to the growing
database of environmental proxy data collected under the auspices of the
ITASE (International TransAntarctic Scientific Expedition) program. In
Antarctica, the instrumental record of climate is particularly short (~40
years except in a few isolated locations on the coast), and ice core proxy
data are the only means available for extending this record into the past.
The use of stable isotopes of water (18-O/16-O and D/H ratios) from ice
cores as proxies for temperature is well established for both very short
(i.e. seasonal) and long timescales (centuries, millennia). Using
multivariate regression methods and shallow ice cores from West
Antarctica, a reconstruction of Antarctic climate over the last ~150 years
has been developed which suggests the continent has been warming, on
average, at a rate of ~0.2 K/century. Further improving these
reconstructions is the chief motivation for further extending the US ITASE
project. Ten to fifteen shallow (~ 100 m) from Victoria Land, East
Antarctica will be obtained and analyzed. The core will be collected along
a traverse route beginning at Taylor Dome and ending at the South Pole.
Age-depth relationships for the cores will be determined through a
combination of stable isotopes, visual stratigraphy and seasonal chemical
signatures and marker horizons. Reconstructions of Antarctic climate
obtained from these cores will be incorporated into the global network of
paleoclimate information, which has been important in science, policy and
educational contexts. The project will include graduate student and
postdoctor$
field experience.