edu.ucar.opensky::articles:8211 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T16:07:31.120877 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7rb7521 Intermittent turbulence associated with a density current passage in the stable boundary layer 2002-11-01T00:00:00Z publication https://n2t.org/ark:/85065/d7rb7521 https://doi.org/10.1023/A:1019969131774 Sun, Jielun author Burns, Sean author Lenschow, Donald H. author Banta, R. author Newsom, R. author Coulter, R. author Frasier, S. author Ince, T. author Nappo, C. author Cuxart, J. author Blumen, W. author Lee, X. author HU, X. author UCAR/NCAR - Library publisher Using the unprecedented observational capabilities deployed during the Cooperative Atmosphere-Surface Exchange Study-99 (CASES-99), we found three distinct turbulence events on the night of 18 October 1999, each of which was associated with different phenomena: a density current, solitary waves, and downward propagating waves from a low-level jet. In this study, we focus on the first event, the density current and its associated intermittent turbulence. As the cold density current propagated through the CASES-99 site, eddy motions in the upper part of the density current led to periodic overturning of the stratified flow, local thermal instability and a downward diffusion of turbulent mixing. Propagation of the density current induced a secondary circulation. The descending motion following the head of the density current resulted in strong stratification, a sharp reduction in the turbulence, and a sudden increase in the wind speed. As the wind surge propagated toward the surface, shear instability generated upward diffusion of turbulent mixing. We demonstrate in detail that the height and sequence of the local thermal and shear instabilities associated with the dynamics of the density current are responsible for the apparent intermittent turbulence. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2002 Springer. None eng geoscientificInformation