Current Improvements to the Graphical Turbulence Guidance Nowcast (GTGN) Algorithm

The Graphical Turbulence Guidance Nowcast (GTGN) product provides near real-time information on the current state of atmospheric turbulent conditions that can impact aircraft across the continental US. All sources of turbulence are represented in the nowcast, which is created by combining short-term turbulence forecasts from the Graphical Turbulence Guidance (GTG) product with the most recent turbulence observations available, such as pilot reports (PIREPs), automated in situ eddy dissipation rate (EDR) reports from commercial aircraft, and EDR estimates from the NEXRAD Turbulence Detection Algorithm (NTDA). GTGN has been developed as a tactical turbulence product to help dispatchers and pilots make short-term routing and operational decisions, enhancing safety in the National Airspace System (NAS). Recently, GTGN1 satisfied the requirements of the FAAs Safety Review Management Panel (SRMP) and its approval paves the way for its dissemination to users.
Development of a second generation GTGN algorithm is currently underway with the goal to further improve nowcast accuracy. One major upgrade will be the transition from the 13km RAP based GTG to using the 3km HRRR based GTG output that will soon be available. Because of the higher underlying model resolution, this should improve nowcasts of all forms of turbulence. Further, the use of other data sources will be included, such as lightning, satellite, and ground based wind observations, with the goal of enhancing the identification of convectively induced turbulence (CIT) and low level turbulence. This presentation will focus on the GTGN2 algorithm and use case studies to illustrate the algorithm’s improvement to turbulence nowcasting.
This research is in response to requirements and funding by the Federal Aviation Administration (FAA). The views expressed are those of the authors and do not necessarily represent the official policy or position of the FAA.