Circulation retrieval of wake vortex in fog with a side-looking scanning radar

Knowledge of aircraft wake vortex circulation is very essential for promoting aviation safety and airport capacity. In foggy conditions, cloud water droplets suspended as fog (here called fog drops) inside the wake have almost identical velocity with the wake vortex due to the weak inertia of the droplets. By taking this property into account, we propose two methods to retrieve the circulation of wake vortex in fog with a side-looking scanning radar. In the methods, while the radar beam scans alternatively up and down, the vortex cores are identified from the Doppler spectra at different incident angles, and the circulation is finally boiled down to very simple expressions related to the Doppler velocities. Numerical simulation results verify the good performance of the methods.