Infrasonic Detection of Atmospheric Turbulence

American Daedalus proposes to investigate the feasibility of infrasonic monitoring as a method of detecting aircraft-scale turbulence.nbsp; An infrasonic sensor network monitoring acoustic energy below 20Hz could fill gaps in existing turbulence detection systems, thus providing the basis for a service that improves the efficiency, capacity, and safety within the air traffic management system. The objective of Phase I is to implement an infrasonic processing system that classifies infrasound as originating from a region of aircraft-scale turbulence. Previous theoretical and observational studies have found that infrasound associated with atmospheric turbulence exhibits a power-law spectrum with low overall coherence, a feature shared by infrasonic emissions from atmospheric convection. Therefore the initial classifier design will compare infrasonic signal characteristics with convective indicators such as NEXRAD and lightning strike data. The existence of aircraft scale turbulence will be determined by collecting in situ pilot reports in the region of the infrasonic sensor array. The classifier will be applied to data measured by an array of three highly sensitive, NASA-developed electret microphones. An off-the-shelf spatiotemporal database containing infrasonic analyses and meteorological data will enable an innovative data analysis with two aims. First, the performance of the classifier will be gauged by a sensitivity analysis and by studying missed events/false alarms for physical insight. Second, the detected turbulence events will be used to develop a more complete model of infrasonic emissions from aircraft-scale turbulence. This technology has the potential of becoming the only persistent method for monitoring of turbulence associated with clouds and in clear air, thus lessening the impact of a weather phenomenon which costs the aviation industry an estimated $150M to $500M per year due to factors like scheduling delays and injury compensation.