Detecting Aircraft Turbulence with Laser Radar

A laser-based method of detecting unsteady airflow could provide a solution to sudden airplane turbulence.

Clear-air turbulence (CAT) occurs independently of cloud cover, making it neither visible to the eye nor measurable with sensors. Recent results in atmospheric research indicate that such turbulence will occur more frequently in the future due to climate change.

Wind shear often occurs along the jet stream. This involves extended layers of air that move against each other horizontally at different speeds. Particularly strong wind shear can create waves that ultimately break, like waves on water. When a wave breaks, it causes vortices in the air, or turbulence — specifically clear-air turbulence. Courtesy of Astronautilus.

To address this, researchers at the German Aerospace Center (DLR) Institute of Atmospheric Physics developed a laser-based light detection and ranging (lidar) instrument to be installed onboard an aircraft.

Researchers at the DLR Institute of Atmospheric Physics have developed a laser-based instrument to detect and predict clear-air turbulence from a distance. Under the European joint project DELICAT, the new technology is currently being tested by the DLR and its project partners. Courtesy of DLR.

Through emitting short-wave UV laser radiation along the direction of flight, the density of the air is determined from backscatter values measured for the air molecules, oxygen and nitrogen. Fluctuations in this density then provide information about turbulence in distant areas, making it visible and predictable for the first time.

Under the European joint project DELICAT (demonstration of lidar-based clear-air turbulence), test flights are currently taking place on a modified Cessna Citation jet operated by the National Aerospace Laboratory. The UV-lidar system has been installed for the laser measurements.

A lidar instrument can be installed onboard an aircraft and emits short-wave UV laser radiation along the direction of flight. The density of the air is determined from the backscatter value measured for the air molecules, oxygen and nitrogen. Fluctuations in this density then provide information about the turbulence there. Courtesy of DLR.

After the testing has successfully concluded, the data will be analyzed. Researchers will not only be able to demonstrate their new technology, but the unique data set will also provide them with important information on the formation mechanisms of complex atmospheric processes.

For more information, visit: www.dlr.de