Integrated Turbulence Forecasting Algorithm Meteorological Evaluation

Encounters with unexpected, hazardous, clear-air turbulence (CAT) pose significant safety risks to the aviation community. To mitigate these safety hazards, the Federal Aviation Administration (FAA) Aviation Weather Research Program (AWRP) has sponsored research and development activities aimed at improving the detection and forecasting of CAT. Utilizing AWRP funding, the Research Applications Program at the National Center for Atmospheric Research (NCAR/RAP) has developed the Integrated Turbulence Forecasting Algorithm (ITFA).

ITFA is composed of numerous CAT indices that are calculated using the forecasted fields of the Rapid Update Cycle (RUC) and assigned weighting factors based on turbulence observations obtained from pilot reports (PIREPS) and aircraft vertical accelerometer measurements. The output and weighting factors are integrated, with the resulting final output displayed as graphical forecasts of CAT.

In order to gain feedback about the operational effectiveness of the ITFA, the FAA William J. Hughes Technical Center (WJHTC) Communication/Navigation/Surveillance Engineering and Test Division, Weather Branch (ACT-320), performed an event-driven meteorological evaluation of the ITFA during the period 1 January to 30 April 2000. The evaluation involved using Significant Meteorological Information advisories (SIGMETs) and PIREPS to identify regions of significant CAT, and then correlating these turbulent regions with the output produced by the ITFA before, during, and after the CAT events. Results of the evaluation identified the added value of the ITFA products to the aviation forecasting community and provided NCAR valuable insight for future development of the algorithm.