Effects of buildings on wind shear at the airport: Field measurement by coherent Doppler lidar

Abstract

Wind shear has a negative impact on aircraft safety, particularly during takeoff and landing processes. The buildings inside or around the airport can induce wind shear by disturbing the airflow along the glide path. This paper investigates the building-induced wind shear along the glide path of aircraft by utilizing two coherent Doppler lidar systems deployed at Beijing Capital International Airport. A well-designed coordinated scanning strategy of lidar was used to measure the building-induced wind shear along the glide path and the wind field influenced by buildings. With a correlation coefficient of 0.97 for wind speed and 0.99 for wind direction, the wind field estimated by lidar was well validated by those from sonic anemometers. In addition, the lidar-observed wind shear events are verified by pilot reports. The results show that building wakes bring the velocity deficit and turbulence increase along the glide paths. It is susceptible to wind shear due to the rapidly changing wind speeds when the aircraft flies through these wake regions. The relative frequencies of wind shear events reached above 70 and 50 at 36L and 01, respectively, in the wind direction range of 270°∼300° with a wind speed greater than 12 m/s. The statistical analysis of lidar-observed wind shear reveals that the wind shear frequently occurs within the height of 40 ∼ 80 m and the distance of 763 ∼ 1526 m at both 36L and 01.