Nocturnal low-level-jet generated gravity waves and turbulence over Oklahoma City during inversion breakup

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Monday, 18 January 2010: 5:00 PM
B308 (GWCC)
Yansen Wang, U.S. Army Research Laboratory, Adelphi, MD; and D. Garvey

Boundary layer wind data observed by Doppler lidar over Oklahoma City during the JU2003 indicate that a strong nocturnal low-level-jet (LLJ) dominated the boundary layer flows during the early morning hours of most of the intensive observation days. Gravity waves appeared in this type of flow in the late morning due to the strong shear of the LLJ and the weak temperature stratification below the jet. In this presentation, we intend to show the LLJ-generated gravity waves by analyzing the sonic anemometer, Doppler lidar, and radiosonde observational data. The mechanism of the gravity wave generation by the LLJ is investigated using a linear stability analysis. The wavelength and phase speed of the wave are computed using the spectral and wavelet methods. The wind signals are separated into waves and turbulence using a wavelet decomposition method. The momentum fluxes due to the wave motions and turbulent fluctuations are computed.