News

Science instrument built in Utah will gather data from Earth’s highest clouds to gain insight to change in global climate

By Karen Wolfe
Utah State University/Space Dynamics Laboratory
April 5, 2007

North Logan—Scientists will soon begin collecting data from Earth’s highest clouds with an instrument designed and built at Utah State University’s Space Dynamics Laboratory (SDL) in North Logan, Utah. Many scientists believe that recent changes in these high-altitude, night-shining clouds may be indicators of change in our global climate and weather patterns.

The Solar Occultation for Ice Experiment (SOFIE) built by SDL is part of NASA’s Aeronomy of Ice in the Mesosphere (AIM) mission led by Hampton University in Virginia. AIM seeks to gain a better understanding of these dramatic clouds, which hover at the edge of space.

Night-shining or noctilucent clouds (NLCs) have historically been observed only at polar regions above 50 degrees latitude. In 1999, however, Dr. Mike Taylor, a physicist at Utah State University and now a co-investigator with the AIM science team, observed and photographed these clouds in Logan, Utah, which lies at a latitude of 41.7 degrees north. At roughly the same time, scientists from the University of Colorado spotted similar phenomena in Boulder, Colorado at 40.0 degrees north latitude. 

Along with forming at lower latitudes, NLCs have also increased in number and brightness, leaving scientists puzzled about the cause for this behavior. 

While common clouds linger just five miles above Earth’s surface, NLCs, also known as polar mesospheric clouds (PMCs), form more than 50 miles above the surface in a layer of the atmosphere known as the mesosphere. Only seen during the summer months, they appear at twilight when the sky is dark and the sun has fallen just below the horizon.

Recent temperature measurements indicate that the mesosphere is growing colder.  At the same time, Earth’s lower atmosphere temperature appears to be increasing, leading scientists to believe that NLCs may be indicators of global climate change.

Like ordinary clouds, the brightest NLCs are made of frozen water that forms ice crystals around particulate matter. Clouds close to Earth’s surface form ice crystals around dust that has been kicked up from Earth’s surface. Many scientists believe that NLCs are made of ice crystals formed around cosmic dust.

SOFIE will take accurate temperature measurements of the mesosphere while also measuring water vapor, carbon dioxide, methane, nitric oxide, ozone PMCs and aerosols. From these measurements, scientists hope to determine what combination of atmospheric constituents is required to form NLCs.

Two additional science instruments on the AIM payload will complement data obtained from SOFIE. The University of Colorado’s Laboratory for Atmospheric & Space Physics built both the Cloud Imaging and Particle Size (CIPS) experiment and the Cosmic Dust Experiment (CDE). CIPs is a four-camera instrument that will take space-based pictures of NLCs, while CDE will measure meteoric dust entering Earth’s atmosphere.

SOFIE represents an on-going relationship between SDL, Dr. James Russell of Hampton University and GATS, Inc. of Newport News, VA. Russell is the principal investigator of the science mission. Larry Gordley, president of GATS, is a co-investigator of the AIM mission and principal investigator for the SOFIE instrument. Dr. Mark Hervig, co-investigator for the SOFIE instrument, is also from GATS. Data from SOFIE will be processed by GATS.

SOFIE and the AIM mission are scheduled to launch on April 25, 2007 from Vandenberg Air Force Base in California onboard a Pegasus XL rocket. Once launched, the AIM spacecraft will follow a polar orbit some 300 miles above Earth and will record data over four PMC seasons during its two-year flight.