U.Colorado Satellite Indicates Regional Warming Variations From Sun During Solar Cycle (Forwarded)

Office of News Services
University of Colorado-Boulder
Boulder, Colorado

Contact:
Tom Woods, (303) 492-4224
Jim Scott, (303) 492-3114

Nov. 13, 2007

CU Satellite Indicates Regional Warming Variations From Sun During Solar
Cycle

A NASA satellite designed, built and controlled by the University of
Colorado at Boulder is expected to help scientists resolve wide-ranging
predictions about the coming solar cycle peak in 2012 and its influence on
Earth's warming climate, according to the chief scientist on the project.

Senior Research Associate Tom Woods of CU-Boulder's Laboratory for
Atmospheric and Space Physics said the brightening of the Sun as it
approaches its next solar cycle maximum will have regional climatic impacts
on Earth. While some scientists predict the next solar cycle -- expected to
start in 2008 -- will be significantly weaker than the present one, others
are forecasting an increase of up to 40 percent in the Sun's activity, said
Woods.

Woods is the principal investigator on NASA's $88 million Solar Radiation
and Climate Experiment, or SORCE, mission, launched in 2003 to study how and
why variations in the Sun affect Earth's atmosphere and climate. In August,
NASA extended the SORCE mission through 2012. The extension provides roughly
$18 million to LASP, which controls SORCE from campus by uploading commands
and downloading data three times daily to the Space Technology Building in
the CU Research Park.

Solar cycles, which span an average of 11 years, are driven by the amount
and size of sunspots present on the Sun's surface, which modulate brightness
from the X-ray to infrared portion of the electromagnetic spectrum. The
current solar cycle peaked in 2002.

Solar activity alters interactions between Earth's surface and its
atmosphere, which drive global circulation patterns, said Woods. While
warming on Earth from increased solar brightness is modest compared to the
natural effects of volcanic eruptions, cyclical weather patterns like El
Nino or human emissions of greenhouse gases, regional temperature changes
can vary by a factor of eight.

During the most recent solar maximum, for example, the global mean
temperature rise on Earth due to solar-brightness increases was only about
0.2 degrees Fahrenheit, said Woods. But parts of the central United States
warmed by 0.7 degrees F, and a region off the coast of California even
cooled slightly. A paper on the coming decade of solar activity by Woods and
Judith Lean of the Naval Research Laboratory in Washington, D.C., was
published online Oct. 30 in the scientific newsletter, Eos.

"It was very important to the climate change community that SORCE was
extended, because it allows us to continue charting the solar irradiance
record in a number of wavelengths without interruption," Woods said. "Even
relatively small changes in solar output can significantly affect Earth
because of the amplifying affect in how the atmosphere responds to solar
changes."

With mounting concern over the alteration of Earth's surface and atmosphere
by humans, it is increasingly important to understand natural "forcings" on
the Sun-Earth system that impact both climate and space weather, said Woods.
Such natural forcing includes heat from the Sun's radiation that causes
sal****er and freshwater evaporation and drives Earth's water cycle.

Increases in UV radiation from the Sun also heat up the stratosphere --
located from 10 miles to 30 miles above Earth -- which can cause significant
changes in atmospheric circulation patterns over the planet, affecting
Earth's weather and climate, he said. "We will never fully understand the
human impact on Earth and its atmosphere unless we first establish the
natural effects of solar variability."

SORCE also is helping scientists better understand violent space weather
episodes triggered by solar flares and coronal mass ejections that affect
the upper atmosphere and are more prevalent in solar maximum and declining
solar cycle phases, said Woods. The severe "Halloween Storms" in October and
November 2003 disrupted GPS navigation and communications, causing extensive
and costly rerouting of commercial "over-the-poles" jet flights to lower
latitudes, he said.

Woods also is the principal investigator on a $30 million instrument known
as the Extreme Ultraviolet Variability Experiment, or EVE, one of three
solar instruments slated for launch on NASA's Solar Dynamic Observatory in
December 2008. Designed and built at LASP and delivered to NASA's Goddard
Space Flight Center in Maryland last September, EVE will measure precise
changes in the Sun's UV brightness, providing space weather forecasters with
early warnings of potential communications and navigation outages.

About one-third of the annual SORCE budget goes for commanding and
controlling the satellite, roughly one-third for producing public data sets
and one-third for analyzing how and why the Sun is changing, he said.
"CU-Boulder students are our lifeblood," said Woods. "They are involved in
all aspects of the SORCE mission, from uploading commands to the spacecraft
to analyzing data."

A podcast on SORCE featuring Woods can be accessed on the Web at:
http://www.colorado.edu/news/podcasts/

For more information on SORCE, visit the Web at:
http://lasp.colorado.edu/sorce/news_letter.html