Taking temp of sun’s impact on climate

U. COLORADO (US) — A $28 million instrument scheduled to launch this week aboard NASA’s Glory mission will study changes in the sun’s brightness and its impact on Earth’s climate.

The Total Irradiance Monitor (TIM) will point directly toward the sun to measure both short- and long-term fluctuations in the sun’s energy output as it reaches the top of Earth’s atmosphere.

Such measurements are important because variations in the sun’s radiation can influence long-term climate change on Earth.

NASA’s Solar Radiation and Climate Experiment, a $100 million satellite was launched in 2003 and is equipped with a first-generation TIM instrument and three other solar measuring instruments.

“We’d like to know how the sun’s energy changes over both the short and long term,” says Greg Kopp, research scientist at the University of Colorado and principal investigator on the TIM.

“This spacecraft is carrying extremely sensitive instruments for monitoring solar variability, which makes the mission especially relevant given climate change on Earth and the importance of determining the natural influence on those changes.”

Glory will join five other Earth-observing satellites as part of the Afternoon Constellation, or “A-Train,” a tightly grouped series of spacecraft that circle the globe several times each day to gather information on Earth’s biosphere and climate, including hurricane behavior and climate change.

The A-Train spacecraft follow each other in close formation, flying mere minutes apart, orbiting the Earth about once every 100 minutes.

By measuring solar radiation changes, scientists hope to determine how much energy reaches Earth on timescales of decades to centuries and how they influence Earth’s long-term climate.

Scientists previously have shown that the overall output of the sun can change up to about 0.1 percent over the duration of a solar cycle, which lasts about 11 years. But such short-term variations don’t  explain the warming seen on Earth in the past several decades.

The vast majority of climate scientists agree global warming is due primarily to human-produced greenhouse gases building up in the atmosphere.

“In attributing climate change causes, solar variability measurements such as those from Glory are necessary to discriminate the natural from the human-caused effects on the climate,” Kopp says.

Glory is managed by NASA’s Goddard Space Flight Center in Greenbelt, Md. Launch management is provided by NASA’s Launch Services Program at the agency’s Kennedy Space Center in Florida.

More news from University of Colorado: www.colorado.edu/news/