Space technologies adapted to fight terrorism
Detection technologies developed
by Livermore researchers to study astrophysical phenomena such as
black holes and supernovas have a new down-to-earth applicationhelping
to fight terrorism. Now, technologies for finding and imaging space
phenomena are assisting in the detection of nuclear materials or
One such technology is the
High-Energy Focusing Telescope (HEFT), scheduled to be launched
in the fall of 2003. HEFT will be used primarily to study how supernovas
create and distribute most of the elements heavier than helium.
The telescopes integrated circuits work in conjunction with
cadmiumzinctelluride crystals to detect and measure
faint gamma-ray signals. HEFTs mirrors focus the gamma rays
into imaging detectors to produce clear pictures with high spectral
Simon Labov, the director
of Livermores Radiation Detection Center, explains that In
both astrophysics and nuclear materials, the emissions are faint,
and there is a lot of background noise. Having advanced high-sensitivity
detectors can solve both problems. In effect, the efforts of about
50 researchers and $20 million spent during the past 5 years is
being leveraged for detecting nuclear materials to combat
terrorism and support homeland security.
Detector technologies for
studying black holes in space will also be used in small hand-held
detectors for finding and analyzing nuclear materials on Earth.
Contact: Simon Labov (925) 423-3818 (email@example.com).
Uncertainties found in global warming satellite
Using a new analysis of
satellite temperature measurements, a research team including Livermore
scientists has discovered that satellite data used to measure temperature
changes in various layers of the atmosphere contain uncertainties
that may hamper the detection of human effects on climate change.
Since 1979, microwave sounding
units (MSUs) flown on 12 polar-orbiting U.S. weather satellites
have measured the microwave emissions of oxygen molecules, which
are related to atmospheric temperature. By monitoring these emissions
at different frequencies, researchers can work backward to determine
temperature changes in various layers of the atmosphere.
Analysis of MSU data, which
until recently was done solely by researchers from the University
of Alabama at Huntsville, has indicated little or no warming of
the troposphere (the lowest layer of the atmosphere) since 1979.
These findings bring into question both the reality of human-induced
global warming and the reliability of computer climate models that
predict tropospheric warming in response to increases in greenhouse
gases. The University of Alabama results are also at odds with thermometer
measurements indicating pronounced warming of Earths surface
during the satellite era.
Analysis of MSU data is,
however, complicated by factors such as the gradual decay and drift
of satellite orbits, which affect the time of day at which MSUs
measure atmospheric temperatures, and by problems with MSU calibration.
Recently, a group of researchers
led by Carl Mears, Matthias Schabel, and Frank Wentz of Remote Sensing
Systems in Santa Rosa, California, conducted an independent analysis
of the raw MSU data. Using different methods to correct for satellite
orbital drift and calibration problems, they found that the troposphere
probably warmed by roughly 0.18°F per decade from 1979 to 2001,
for a total rise in tropospheric temperature of 0.4°F over that
Livermore scientists Benjamin
Santer, Karl Taylor, James Boyle, and Charles Doutriaux, along with
researchers from Remote Sensing Systems, the National Center for
Atmospheric Research, Lawrence Berkeley National Laboratory, and
the University of Birmingham in England, are exploring the implications
of these uncertainties for the study of human effects on climate.
Their findings are reported in the May 1, 2003, edition of Science
Express, the online publication of Science magazine.
The teams modeling
yielded detailed patterns, or fingerprints, of tropospheric temperature
change. These fingerprints are identifiable in the Remote Sensing
Systems analysis of MSU data showing a warming troposphere, but
not in the University of Alabama analysis.
According to Livermores
Santer, lead author of the Science Express paper, In
the last 24 years, satellites have helped us observe the climate
of our planet more intensively and systematically than at any other
time in Earths history. Yet even over the satellite era, there
are still large uncertainties in our estimates of how tropospheric
temperatures have changed. Its important to take these uncertainties
into account in evaluating the reliability of climate models. .
. . Our detection results point toward a real need to reduce current
levels of uncertainty in satellite temperature measurements.
Contact: Benjamin Santer (925) 422-7638 (firstname.lastname@example.org).