Automatic Coherent Structure Detection in a Dual Doppler Lidar Horizontal Wind Field Data Set

Coherent structures are described as quasi-periodic patterns in turbulent flow fields. In many studies the impact of these structures on boundary layer processes, such as the transport of momentum, heat and trace gases has been proven. Coherent stucture measurements are challenging since measurement with high temporal and horizontal resolution are required. At the IMK-TRO at KIT two powerful ground based Doppler lidars are operated in a dual-Doppler mode. With simultaneous measurements we can probe the turbulent horizontal wind field in low altitudes with a high temporal and horizontal resolution, and thus explore up to now hidden details of the boundary layer. During the HOPE field campaign in spring 2013 in Jülich (Germany) we were able to gain a data set containing more than 300 hours of horizontal wind field measurements. We compare a wavelet based automatic coherent structure detection with a subjective method of analysis method. Furthermore the usefulness of other image processing methods will be discussed.