Observations of high frequency fluctuations associated with Kelvin-Helmholtz instability by sodium resonance lidar

We report an observation of KHIs observed by the Sodium Resonance Wind Temperature Lidar system at PFRR, Chatanika, Alaska. The high-resolution sodium density measurements reveal KHIs that were invisible in the raw sodium density data. Analysis of the waves measured by the lidar indicates that the KHIs are directly modulated by the wind shear associated with the semidiurnal tide. We grouped the data based on the Richard numbers, and found that 2.7 minutes fluctuations were associated with 1/4 <Ri < 1, and 2.0 minutes fluctuations were associated with Ri < 1/4. The power of the high frequency fluctuations increases as the Richarson number decreases. These results are consistent with the theory of instability and reveals the potential of metal resonance lidars to detect high frequency fluctuations associated with instabilities and turbulence.