Prediction of Storm Hazards for Aviation

BACKGROUND

Figure 1.  Analysis and forecast products made available to aviation planners via a web-based display.
Figure 1.  Analysis and forecast products made available to aviation planners via a web-based display.

The Next Generation Air Transportation System (NextGen) is a national priority designed to meet the air transportation needs of the United States in the 21st century—in particular, a significant growth in demand for air traffic services, possibly on the order of two to three times today's demand levels. In addition, the number of commercial applications of Unpiloted Aircraft Systems (UAS) has been growing extremely rapidly over the past few years with primary operating space being the lowest 400 feet of the atmosphere. The expected increase in congestion of the NAS hence requires improved detection and prediction of weather hazards and their translation to air traffic flow impacts in order to maintain safety and improve efficiency of Air Traffic Flow Management. The addition of UAS into the skies is an additional flow hazard requiring its own set of weather-related flight hazards.

For the past several years, the NCAR Research Applications Laboratory (RAL) has been engaged in multiple FAA-funded research and development efforts geared toward improved convective weather support on topics ranging from lightning impacts on airport operations and quantifying National Airspace System (NAS)-wide impacts, to developing state-of-the-art CONUS-scale short term predictions of convective storms for strategic planning of the NAS, to optimization of global-scale probabilistic predictions of convective storms in support of ICAO-led harmonization of global weather hazard products.

FY2017 ACCOMPLISHMENTS

An updated, more highly skilled and much faster version of the blending algorithm suite used in CoSPA is currently undergoing technology transfer to the FAA. CoSPA was developed through a collaboration between MIT Lincoln Laboratory, NOAA Earth System Research Laboratory, and NCAR RAL. The FAA recently funded a number of enhancements to the blending component of CoSPA, which was developed by RAL:

  • Improved skill by utilizing forecast uncertainty information to more selectively introduce model predicted storm initiation and growth into the blended forecast
  • Reduced code base for enhanced maintainability
  • Greatly reduced product latency through the code parallelization and interface updates that allow more rapid data processing
  • Added treatment of seasonal and inter-annual variations in the weights used to perform the blending.

While the new blending system is undergoing technology transfer for installation onto the NextGen Weather Processor, the CoSPA forecasts will continue to be made available year-round to aviation planners (i.e., select FAA air traffic flow managers and airline industry partners) via a web-based display.  The display allows users to overlay airports and associated arrival and departure fixes, route structures, and sectors on current and forecast weather facilitating the product’s utility (Figure 1).  

Figure 2.  Economic balance between remaining safety risk and incurred air traffic delays as a function of lightning safety procedure.
Figure 2.  Economic balance between remaining safety risk and incurred air traffic delays as a function of lightning safety procedure.

Work has also continued on quantifying the trade-offs between airport efficiency and safety for handling airport operations when thunderstorms are within range through a collaboration with AvMet. The safety risk experienced by personnel working outdoors at airports (e.g., baggage handlers, food and fuel suppliers) when thunderstorms are in the vicinity has been quantified using detailed models and available datasets.  The impacts of airport closures on the NAS have been simulated using AvMet’s Dynamic Airspace Routing Tool (DART). Detailed analyses of air traffic data in conjunction with lightning data and DART simulations indicate that lightning-induced ramp closures can exert substantial impacts on traffic in to and out of an airport and cause ripple effects through the NAS that result in significant delays and increased workload of air traffic controllers.  The goal of this work is to determine the guidelines for managing airport personnel when thunderstorms are nearby so that the safety risk is minimized while operational efficiency is optimized. Shown schematically, the goal of this new guidance would be to achieve a balance between safety risk and delay costs that occurs near the base of the green curve shown in Figure 2. 

At the other end of the spectrum in terms of space and time scales, work has continued into the optimization of global probabilistic forecasts of thunderstorms which are being developed for strategic planning of transoceanic flights. The Ensemble Prediction of Oceanic Convective Hazards (EPOCH) is a prototype system that has been developed for testing and demonstrating methods for combined ensemble predictions from multiple modeling centers.  Over the past year EPOCH has been modified to compute the likelihood of convective hazards at multiple flight levels (now 30, 35 and 40 Kft). In addition, the EPOCH calibration algorithm has been modified to account for regional variations in bias. This upgrade has improved the overall skill of the combined probabilistic forecasts derived from GEFS and CMCE model ensemble data. Offline studies have also been performed to better understand the behavior of various techniques for calibrating and combining model ensemble information the performance of the final probabilistic forecast product.

FY2018 PLANS

RAL will continue to support the technology transfer of the latest version of the blending used in CoSPA to the FAA for inclusion in the NextGEN Weather Processor (NWP). Additional studies will be performed to assess forecast skill as a function of storm scale to ultimately develop an improved method of blending that takes into account scale-dependent variation in the relative performance of the forecast inputs. 

Current lightning work has been geared toward quantifying (in terms of delays) the impact of lightning on the NAS using air traffic flow simulations and quantifying safety risk costs (in terms of potential for injury and loss of life). The investigation of trade-offs between safe and efficient airport and airline operations under lightning threats is geared towards optimizing the safety guidance while limiting air traffic impacts. Additional work this year will focus on evaluating the performance of various lightning nowcasting techniques for a range of atmospheric conditions in order to improve safety and efficiency of airport operations when thunderstorms are nearby.

Finally, work will continue on the EPOCH system. Enhancements will be made throughg optimization efforts targeted at increasing probabilistic forecast skill and through the development of new products that will aid aviation weather forecasters in their development of guidance products as well as aid airline dispatchers in their strategic planning for transoceanic flights.