Runway Wake Vortex, Crosswind, and Visibility Detection with a Scintillometer at Schiphol Airport

Abstract

We evaluate the performance and investigate the capability of a scintillometer to detect wake vortices, crosswind and visibility near an airport runway. An experiment is carried out at Schiphol airport (Amsterdam, The Netherlands), where an optical scintillometer is positioned alongside a runway. An algorithm is developed to detect wake vortices, and also the strength of the wake vortex, from the variance in the scintillation signal. The algorithm shows promising results in detecting wake vortices and their strengths during the night. During the day, the scintillometer signal is dominated by environmental turbulence and wake vortices are no longer detectable. The crosswind measured by the scintillometer is compared with wind-speed and wind-direction data at the airport. Our results show that, after applying an outlier filter, the scintillometer is able to measure the crosswind over the short time period of 3 s required for aviation applications. The outlier filter does not compromise the capability of the scintillometer to obtain the maximum 3 s crosswind over a 10-min time frame correctly. Finally, a transmission method is used to obtain the visibility from the scintillometer signal, which is then compared with that obtained from a visibility sensor. The scintillometer is able to identify periods of low visibility correctly, although it shows a high amount of scatter around the exact visibility value.

Scintillometry in urban and complex environments: a review

“…Such mechanisms for pollutant dispersion have important implications for air quality, particularly in cities, but are difficult to quantify with point measurements. Scintillometry has also been used to monitor crosswind speeds and detect wake vortices at airports van Dinther et al, 2015a). Besides these applications, knowledge of the crosswind may be important for the quality of scintillometer data itself.…”

“…Periods of interruption or attenuation of the beam by rain, fog, insects or poor air quality are usually removed during quality control. Yet it is also possible to relate signal intensity to visibility (Beyrich et al, 2002a;van Dinther et al, 2015a) and attenuation of microwave (Leijnse et al, 2007b) or infrared (Uijlenhoet et al, 2011) scintillometer beams can be converted to rainfall intensity, offering precipitation measurements at a valuable scale between that of point gauge sensors and radar. In urban areas, where precipitation can be very spatially variable, installing a scintillometer is far more practical than a dense network of rain gauges (Upton et al, 2005).…”