Assessment of Graphical Turbulence Guidance, Global (gtg-g), Part 1

Abstract

The Quality Assessment Product Development Team (QA PDT) was tasked with assessing a globalversion of the Graphical Turbulence Guidance (GTG-G) as part of the transition process to operations. The GTG-G was developed by the Turbulence Product Development Team in theResearch Applications Laboratory at the National Center for Atmospheric Research (NCAR/RAL),under sponsorship from the FAA’s Aviation Weather Research Program (AWRP). The study verifiedthe GTG-G using a variety of observation sets including pilot reports (PIREPs), aircraft reports(AIREPs), aircraft sensor measurements of Eddy Dissipation Rate (EDR), and derived equivalentvertical gust (DEVG). This evaluation of GTG-G provides a preliminary understanding of GTG-G performance, usingcurrent measures of the World Area Forecast Center (WAFCs) for turbulence forecasts, namely,Receiver Operator Characteristics (ROC) curves. The Area under the ROC curve (AUC) of the GTG-G EDR forecasts was compared with that of the operational World Area Forecast System (WAFS)Clear Air Turbulence (CAT) potential. Forecast performance was examined for Moderate-or-Greater(MOG) turbulence only, using the EDR threshold for medium aircraft (0.2). The assessment periodwas 1 July through 31 October 2017