Application of Short-Range LIDAR in Early Alerting for Low-Level Windshear and Turbulence at Hong Kong International Airport

Figure 7

Evolution of an anticyclone depicted by the Lagrangian measure, around 1:50 pm on 15 August (Hong Kong time). (a)–(c) are shown in consecutive order by 20-second intervals. The color plots are the Lagrangian diagnostic, which show coherent vortices when the diagnostic is blow 0 (deformation tensor exhibits complex eigenvalues). The black contours show actual LIDAR coverage. The dashed black contours separate regions of different rotation direction, irrespective of whether vorticity dominates strain. The white isocontours enclose regions with anticyclones; that is, these regions are vorticity dominant and rotate in the clockwise direction. The black straight lines indicate 25RA. In this event, anticyclones pinch off from around the LIDAR and move northwards, whereas new anticyclone patches pinch off across the runway.

(a)

(b)

(c)