The NCAR In Situ Turbulence Detection Algorithm

Historically, there has been one main source for routine turbulence observations for the aviation community, namely pilot reports. Although useful for tactical turbulence avoidance, there have been problems using them for turbulence forecasting and verification due to poor spatial and temporal accuracy, sporadic reporting, and the subjective nature of the reported turbulence intensity. To address these difficulties, NCAR, under sponsorship from the FAA Aviation Weather Research Program, has developed an in situ turbulence reporting system which has now been implemented on several major U.S. commercial air carriers composed of numerous aircraft types. These reports are routine, completely automated, are aircraft independent, have high temporal and spatial accuracy, and are therefore ideal for operational purposes and turbulence case studies. The NCAR In Situ Turbulence Detection Algorithm is coded as a C library which is typically integrated into a suitable onboard computer. The algorithm estimates the cube root of the energy (or eddy) dissipation rate, referred to as EDR, an atmospheric turbulence intensity metric. Besides documenting the algorithm, this document also describes the integrated quality control algorithm, the event triggering logic, the algorithm performance using simulation studies, and steps needed for deployment.