8.6 Doppler Wind Lidar Observations of Nocturnal low-level-jet generated gravity waves before disappearance of the jets

Wednesday, 26 January 2011: 5:00 PM
307-308 (Washington State Convention Center)
Yansen Wang, U.S. Army Research Laboratory, Adelphi, MD; and D. Garvey

Boundary layer wind data observed by Doppler wind lidar over Oklahoma City during the JU2003 indicate that strong nocturnal low-level-jets (LLJs) dominated the boundary layer flows during the early morning hours of most of the intensive observation days. Gravity waves were detected by a Doppler wind lidar in the region of inversion caps in the late mornings due to the strong shear of the LLJ and thin layer of stable temperature stratification below the jets. In this presentation, we will show that this type of gravity waves occurred quite frequently during the JU2003 experiment. The mechanism of the gravity waves generation by the LLJ is investigated using a linear stability analysis with lidar, radiosonde, and profiler data. The wavelength and phase speed of the wave are computed using the spectral and wavelet methods. The turbulent flow under the LLJ is also investigated with the sonic anemometer data.
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