edu.ucar.opensky::articles:22037 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-25T15:52:57.050507 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7639sm1 Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number 2018-08-01T00:00:00Z publication https://n2t.org/ark:/85065/d7639sm1 https://doi.org/10.1209/0295-5075/123/44002 Feraco, F. author Marino, R. author Pumir, A. author Primavera, L. author Mininni, P. D. author Pouquet, Annick author Rosenberg, D. author UCAR/NCAR - Library publisher We investigate the large-scale intermittency of vertical velocity and temperature, and the mixing properties of stably stratified turbulent flows using both Lagrangian and Eulerian fields from direct numerical simulations of the Boussinesq equations with periodic boundary conditions, in a parameter space relevant for the atmosphere and the oceans. Over a range of F'roude numbers of geophysical interest (approximate to 0.05-0.3) we observe very large fluctuations of the vertical components of the velocity and the potential temperature, localized in space and time, with a sharp transition leading to non-Gaussian wings of the probability distribution functions. This behavior is captured by a simple model representing the competition between gravity waves on a fast time scale and nonlinear steepening on a slower time scale. The existence of a resonant regime characterized by enhanced large-scale intermittency, as understood within the framework of the proposed model, is then linked to the emergence of structures in the velocity and potential temperature fields, localized overturning and mixing. Finally, in the same regime we observe a linear scaling of the mixing efficiency with the Froude number and an increase of its value of roughly one order of magnitude. Copyright (C) EPLA, 2018 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 2018 EPLA. None eng geoscientificInformation