As part of our continuing effort to provide a turbulence forecast- ing product with true operational utility to the aviation commu- nity, several diagnostic algorithms have been designed to be used with output from Eta (29-km) and RUC-2 (40-km) operational models. The algorithms DTF3.0, DTF4.0, and DTF4.1 (DTF means Diagnostic Turbulence Function) contain formulations to describe turbulence from shear instabilities, gravity wave break- ing, and convection induced turbulence. The algorithm DTF5.0 has been designed for turbulence from shear instabilities in upper tropospheric jet/front system and boundary layer processes. The number in the name of the algorithm signifies improvements in the physical formulations used. Previous verifications of these algorithms with pilot reports (PIREPs) of turbulence and aircraft vertical accelerometer reports (AVARS) show that careful sensi- tivity studies should be conducted to optimize the algorithm per- formance. An algorithm development and verification system (ADVS) has been developed for this purpose. Preliminary results of a verification with RUC2 output for December 1997 show that DTF5.0, with the proper parameters and initial conditions, has skill in forecasting moderate or greater turbulence events associ- ated with heavy aircraft (mostly commercial) for elevations above 20,000 ft. The other algorithms exhibit lesser performance. The advantage of the ADVS is that several algorithms can be ver- ified, calibrated, and compared with the same model output and turbulence observations (e.g., PIREPs, AVARS), and for the same verification time period.
At the time of the conference, results using the ADVS for verifi- cation for a year (December 1997 to December 1998) of several algorithms (including the DTF series) will be presented.
The 8th Conference on Aviation, Range, and Aerospace Meteorology