In the next few weeks, researchers at Poker Flat Research Range will study polar ice clouds and their environment in the late summer skies of Fairbanks. These studies will use the Poker Flat Incoherent Scatter Radar that can detect turbulent structures in the upper atmosphere.
The radar has the unique ability to steer a beam rapidly while capturing an image of the atmosphere as it scans the sky. This reveals the horizontal pattern of the turbulence in the upper atmosphere. At the same time researchers will employ laser radar, or lidar, systems also at PFRR to measure the ice clouds that form in the upper atmosphere in August.
These clouds forming at altitudes of 50 miles (80 kilometers) are visible after midnight in late summer in Alaska as luminous wispy, "night shining" clouds. Though solar radiation is at its most intense during summer, the solar heating actually has a cooling effect on the mesopause region of the atmosphere. Noctilucent clouds are a result of a warmer lower atmosphere pushing a pocket of air upwards that cools to make the ice clouds.
The combined radar and lidar observations will allow scientists to specifically investigate the role of turbulence in the formation of these clouds and address the larger questions about how turbulent processes determine the structure of the atmosphere through transport of heat and minor species. Describing turbulence in the atmosphere remains a major challenge as turbulent motions occur at scales that are often too small to measure and are not resolved by current computer models. Noctilucent clouds provide a natural laboratory for revealing the effects of turbulence on the atmosphere.
The measurement campaign will be conducted by scientists and students from the Stanford Research Institute and the Geophysical Institute of the University of Alaska Fairbanks. The research is an extension of findings that stem from a 2007 conference held at UAF, the Eighth International Workshop on Layered Phenomena in the Mesopause Region.