Abstract
The low-level wind shear is defined as a sharply change of the wind speed or wind direction within 600 m above the ground level. Due to affecting the airspeed of aircraft during take-off and landing phases, the wind shear can result in the disastrous aircraft accidents. The lidar team at Ocean University of China (OUC) carried out the particular research of the low-level wind shear at Beijing Capital International Airport (BCIA) in 2015 and 2016 by operating a pulse coherent Doppler lidar (PCDL) system. In this field experiment, the radial resolution is 30 m while the angle resolution is 0.1° and the updating rate of observation data is 4 Hz. On account of the high spatial and temporal resolution, the small-scale meteorological phenomenon can be captured. The low-level wind shear is observed by different scanning modes including 5-Doppler beam swing (5-DBS), step-wise plane-position indicator (PPI), multi-elevation PPI, range-height indicator (RHI) and glide path scan. The experiment configuration, the PCDL system, the observation modes and the case study of the wind shear are proposed and experimentally demonstrated. The quick-look algorithms which identifies the wind shear alarm based on the radial velocity data have been developed and tested. A case study of the wind shear shows that the events of low-level wind shear at the southern end of 18R/36L are suspected to be caused by buildings and rows of trees along the glide path under strong northwest wind conditions. Meanwhile, more than 2000 PPI scans have been analyzed to indicate the relationship between wind shear intensity and ramp length. Preliminary validations of the algorithms against wind shear reports from the crew and the terminal control office indicated positive skill. Totally, 14 wind shear cases have been validated by reports from the crew during field observation campaign.
Highlights
A case study shows that the low level wind shear events at the southern end of 18R/36L runway were mainly caused by the trees and buildings along the glide path under strong northwest wind conditions
Wind speed profiles are effective tools to illustrate the wind speed varying with height, it is useful to identify the wind shear occurring at different height
Wind speed retrieved from the PPI scan data is related to the intercept angle between the laser beam pointing direction and the prevailing wind
Summary
A case study shows that the low level wind shear events at the southern end of 18R/36L runway were mainly caused by the trees and buildings along the glide path under strong northwest wind conditions. Effective wind shear alarm systems speed measurement accuracy is 0.1 m/s. Qualification Spatial Resolution (Transverse)* Radial Spatial Resolution Measurement Range** LOS Velocity Update Rate Wind Profile Update Rate
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