Observations of Boundary Layer Coherent Structures with the MetroWeather Coherent Doppler Lidar

Doppler lidar systems are often used for studies of the atmospheric boundary layer and pre-convective environments. These systems enable clear-air studies and can complement radar observations through improving the near-surface measurements of flow and turbulent structures. The University of Oklahoma Advanced Radar Research Center (ARRC) has recently assembled a mobile system using the high-sensitivity MetroWeather Coherent Doppler Lidar (CDL), which features a Nyquist velocity of 97.7 m/s and a sampling frequency of 250 MHz. With the CDL, we target observing turbulent coherent structures on both clear-air days and in supercell thunderstorm inflow regions. This is motivated by recent numerical modeling studies that indicate turbulent coherent structures may play a major role in supercell tornadogenesis. In this study, we present low-elevation plan position indicator (PPI) and range-height indicator (RHI) scans of the atmospheric boundary layer to showcase how the CDL captures coherent structures. Observations from both the Hampton, Virginia MetroWeather site and the mobile CDL system in Oklahoma are shown, including radial velocity and derived vertical vorticity measurements, which are used to visualize turbulent structures. A dual-Doppler analysis was also performed in coordination with the National Severe Storms Laboratory’s Halo Doppler lidar system to view the 3D velocity field of turbulent coherent structures. The scanning strategies used in this study are similar to what is used in proximity to supercell storms, showing that the MetroWeather CDL is capable of tracking turbulent coherent structures as they interact with storm-scale features.