For much of the past decade, RAP has been studying the characteristics, physical causes and aviation impact of low-level turbulence induced by air flow over terrain. In addition, RAP has played key roles in designing, constructing and deploying real-time operational systems to warn the aviation users about a presence of significant terrain-induced hazards. RAP's heavy involvement in this field started with a program in Hong Kong where a new airport at Chep Lap Kok was being built in close proximity to a major mountain barrier. After extensive scientific studies that included nearly a year of field observations and extensive high-resolution numerical modeling, an operational system for detecting and forecasting the presence of significant turbulence near the airport was built and deployed. The system was integrated with the Terminal Doppler Weather Radar (TDWR) system and continues to provide real-time hazard information for Chep Lap Kok.

The knowledge and experience gained from the Hong Kong program were further tested in a FAA-sponsored field program in Colorado Springs in the wake of the unresolved crash of a United 737 there in 1991. Although no specific clues to that crash were revealed, the Colorado Springs study was able to show that the instruments and techniques for detecting terrain-induced turbulence in Hong Kong were applicable in the very different Colorado Springs environment.

More recently, RAP has been studying terrain-induced turbulence in the vicinity of the Juneau International airport, Alaska. The problem in Juneau is complicated by a complex terrain around the airport, the need for very unique arrival and departure routes to avoid the terrain, and frequent episodes of very low ceiling and visibility. RAP has conducted two intensive field data collections in the area and has generally confirmed that the conclusions of the Hong Kong and Colorado Spring programs carry over into Juneau, although the complexity of the Juneau situation and the harnesses of the climate cloud those results somewhat. An operational system for providing wind information of a crucial importance for aviators has already been deployed there, and efforts are underway to upgrade the system to provide specific terrain-induced hazard warnings.

Research Lead: Alex Praskovsky