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How climate change models could get better, thanks to NASA

NASA is set to launch satellite Glory early Wednesday. It will measure incoming sunlight and atmospheric particles, both key to crafting better climate models.

By Staff writer / February 22, 2011

This undated image provided by NASA shows science workers monitoring a crane lifting NASA's Glory satellite's upper stack for attachment onto the Taurus XL rocket at Vandenberg Air Force Base in California. NASA is set to launch Glory, its latest Earth-orbiting satellite on a $424 million mission to study airborne particles spewed from volcanoes, dust storms, forest fires and the burning of fossil fuels.

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In the dark of night, scientists expect to launch a satellite they hope will provide new insights into the energy the sun provides for Earth's climate in the light of day.

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At 2:09 a.m. Pacific Standard Time Wednesday, NASA is launching Glory on a mission that will give the most accurate measurements yet of incoming sunlight, as well as highly accurate measurements of the size, distribution, and effects of tiny particles in the atmosphere known as aerosols, planners say.

The satellite's data should help atmospheric scientists improve climate models. Better models not only would increase scientists' knowledge of how the climate system operates, but also would help them make more accurate projections of the effects of global warming – even as atmospheric concentrations of greenhouse gases continue to rise, as a result of burning fossil fuels and land-use changes.

Direct and indirect effects of aerosols and black-carbon soot represent "the greatest uncertainty in our ability to predict climate," says Hal Maring, the Glory program scientist at NASA headquarters in Washington.

Aerosols reflect sunlight or absorb it, cooling or heating the atmosphere depending on the particles' size and composition.

Aerosols also can have indirect effects on climate by serving as tiny platforms on which atmospheric water vapor can condense to form cloud droplets.

These tiny particles can vary widely in size, composition, and sources. Aerosols in the atmosphere have natural sources, such as volcanic eruptions, or can result from human activities, such as burning fossils fuels or using wood for cooking and heating. Aerosols from different sources and with different compositions can occupy the same parcel of air.

Numerous field studies have monitored aerosols and black-carbon soot in individual regions. But until now, no project has provided a global view. As a result, the uncertainty in the estimates of aerosols' effects are thought to be as large as the effects being estimated.

"This tells us that we don't know much about aerosols at all," says Michael Mishchenko, the mission's project scientist and a researcher at the Goddard Institute for Space Studies in New York.

The human-caused change in Earth's climate, from the addition of greenhouse gases to the atmosphere, Dr. Mishchenko adds, "also has an uncertainty comparable to the estimate – and almost all of this uncertainty comes from the poor knowledge of aerosols."

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