New satellite data to assess role clouds play in climate change

Information on the physical properties and global distribution of clouds, soon to be collected by a satellite called Terra, could help scientists better predict climate change.

provided by University of Illinois at Urbana-Champaign

wealth of information on the physical properties and global distribution of clouds soon to be collected by a recently launched satellite called Terra could help scientists better predict climate change, says a University of Illinois researcher involved with the project.

"Terra is the flagship of NASA's Earth Observing System Program, an international effort to monitor Earth's climate over the next 15 years," said Larry Di Girolamo, a professor of atmospheric sciences. "During the satellite's six-year lifetime, its five instruments will help scientists understand how clouds, aerosols, air pollutants, oceans, vegetation and ice cover interact with each other and impact the climate we live in."

Di Girolamo's research focuses on clouds. "From a climate-modeling perspective, clouds contribute the largest uncertainty to climate change," he said. "Clouds may have a warming or cooling effect on the planet, depending on the cloud properties. Because clouds are so variable, their effect on global climate has been difficult to quantify."

One of the instruments on Terra is the Multi-angle Imaging Spectro-Radiometer. MISR will be the first instrument to make global, high-resolution, multi-angle, multispectral radiometric measurements of Earth from space. The instrument will characterize cloud, aerosol and surface properties in a manner no other satellite has been capable of.

"It's MISR's ability to look at the same scene from different angles at a high resolution that makes MISR so unique," Di Girolamo said. "You get a lot more information about an object when you look at it from different angles than you do when you look at it from a single angle."

Unlike traditional meteorological satellites that have only one camera, MISR has nine cameras that will successively view portions of the planet in four spectral bands. "By combining spectral and angular signatures, we can gather more information about atmospheric or surface features than spectral signatures alone," Di Girolamo said. "The use of multiple cameras also permits stereoscopic imaging, allowing us to look at clouds in 3-D."

Di Girolamo has been involved with the MISR project for the past decade. As a graduate student, he worked on new techniques for studying clouds from multi-angle data, which helped set the instrument specifications. More recently, he developed the cloud-detection and classification algorithms that will process the complex data needed to better understand the role that clouds play in Earth's climate system.

Lofted into orbit on Dec. 18, the Terra instruments are being rigorously tested prior to measurements of scientific data. For more information on the Terra and MISR missions, visit, a Web page maintained by the National Aeronautics and Space Administration.