The $81.5 million Hiaper aircraft, owned by the National Science Foundation and operated by the National Center for Atmospheric Research (NCAR), has been flying over treacherous whirlwinds, known as rotors, as they form above California's Sierra Nevada mountain range.
The Hiaper (High-performance Instrumented Airborne Platform for Environmental Research) has completed a series of 10-hr flights from its base at Jefferson County Airport in Colorado to California's Owens Valley. The aircraft was also used to study the impacts of the rotors on atmospheric regions as high as the stratosphere. The research should lead to better prediction of these aviation hazards.
Rotors, which form on the lee side of high, steep mountains beneath the cresting waves of air, have contributed to a number of aircraft accidents, but scientists know little about their structure and evolution. Rotors are common in the Sierras because the area has the steepest topography in the continental United States. Owens Valley sits some 10,000 ft directly below the highest peaks of the adjacent mountains.
"From a scientific point of view, this will be a fantastic part of the atmosphere to fly in because of the mountain waves, turbulence, and movements of air masses," says NCAR scientist Jorgen Jensen. "With our instrument payload and flight paths, the amount of data we collect will be absolutely unprecedented for describing airflow over mountains."