Transition NCAR's Graphical Turbulence Guidance Algorithm into NCEP Operations

To support international aviation safety, the Environmental Modeling Center (EMC) continuously improves World Area Forecast System (WAFS) products. The Eddy Dissipation Rate (EDR) is the International Civil Aviation Organization (ICAO) standard for in-situ turbulence reports. The Graphical Turbulence Guidance (GTG) with EDR has been funded by the Federal Aviation Administration (FAA) Aviation Weather Research Program (AWRP) and developed by National Center for Atmospheric Research (NCAR) since early 1990’s. EMC has been coordinating with NCAR to transition the GTG algorithm into National Center for Environmental Prediction (NCEP) operations for both GFS and RAP models by integrating the GTG algorithm into NCEP’s Unified Post Processor (UPP).

There are several benefits in using the UPP to do Research-to-Operations (R2O) transition: 1) align better with operational model upgrades for more efficient R2O transition, 2) reduce run time by using the existing parallel framework in UPP, 3) derive better aviation product by using high resolution grids, and 4) expandable to all eight UPP-supported models to support both deterministic and probabilistic aviation products and to support both CONUS and Global domains.

In July 2017, Global GTG (G-GTG) was successfully implemented into NCEP operation and generated from the GFS UPP at 13km resolution. This will prepare the US for the next WAFS upgrade to increase resolution from 1.25 degree to 0.25 degree grids in the near future. A few case studies will show the success of the transitioned G-GTG. However, the G-GTG product is not public yet. It is being disseminated to GSD for internal verification and verification results will be used by NCAR for calibration and further improvement. The improved GTG will be implemented in Winter 2018 and replace US WAFS Turbulence products.

GSD will implement GTG in the RAP UPP in Feb 2018 through collaboration with EMC and NCAR. Similar to the implementation plan of G-GTG, GTG from RAP UPP will not be disseminated to public until further evaluation is made. The plan is to replace the stand-alone RAP GTG with GTG generated from UPP in the near future.