A Climatology of predicted turbulence and shear near Juneau, Alaska

More than four years of wind data from an array of anemometers and wind profilers is available for the Juneau area as part of the Juneau Terrain-Induced Turbulence Project. The instruments were carefully positioned to measure wind speed and direction related to high turbulence and wind shear along Juneau Airport approach and departure routes. Algorithms to predict turbulence and shear from the instruments were developed using these data in comparison with in situ aircraft measurements collected during two relatively short research efforts; the development process is described elsewhere in this conference. Conditions in twelve predefined hazard boxes along the arrival and departure routes were calculated separately. The resulting prediction algorithms were applied to the four-year data archive to provide an admittedly short-term climatology, which allows a more comprehensive and thorough look at the aviation weather hazards expected for the area.

The climatology will be explored using a number of methods. The predicted hazards in the hazard boxes can be described by wind regime, seasonal differences, extreme values, and their relation to the recorded winds. Southeast flows tend to produce the highest turbulence and shear; Taku wind conditions are related to occasional high turbulence in the Gastineau channel. Mixed and calm conditions are generally benign but can in some cases result in light or moderate turbulence near the airport. Overall results as well as illustrative case studies will be presented. Implications of these results for the operational prototype hazard display to be implemented at the Juneau Airport in Fall 2004 will be discussed.