Interaction between a vertical turbulent jet and a thermocline
MetadataShow full item record
The behavior of an axisymmetric vertical turbulent jet in an unconfined stratified environment is studied by means of well-resolved, large-eddy simulations. The stratification is two uniform layers separated by a thermocline. This study considers two cases: when the thermocline thickness is small and on the order of the jet diameter at the thermocline entrance. The Froude number of the jet at the thermocline varies from 0.6 to 1.9, corresponding to the class of weak fountains. The mean jet penetration, stratified turbulent entrainment, jet oscillations, and the generation of internal waves are examined. The mean jet penetration is predicted well by a simple model based on the conservation of the source energy in the thermocline. The entrainment coefficient for the thin thermocline is consistent with the theoretical model for a two-layer stratification with a sharp interface, while for the thick thermocline entrainment is larger at low Froude numbers. The data reveal the presence of a secondary horizontal flow in the upper part of the thick thermocline, resulting in the entrainment of fluid from the thermocline rather than from the upper stratification layer. The spectra of the jet oscillations in the thermocline display two peaks, at the same frequencies for both stratifications at fixed Froude number. For the thick thermocline, internal waves are generated only at the lower frequency, since the higher peak exceeds the maximal buoyancy frequency. For the thin thermocline, conversely, the spectra of the internal waves show the two peaks at low Froude numbers, whereas only one peak at the lower frequency is observed at higher Froude numbers.
Author Posting. © American Meteorological Society, 2016. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 46 (2016): 3415-3427, doi:10.1175/JPO-D-16-0035.1.
Suggested CitationJournal of Physical Oceanography 46 (2016): 3415-3427
Showing items related by title, author, creator and subject.
Xu, Kang; Huang, Rui Xin; Wang, Weiqiang; Zhu, Congwen; Lu, Riyu (American Meteorological Society, 2017-07-21)The interannual fluctuations of the equatorial thermocline are usually associated with El Niño activity, but the linkage between the thermocline modes and El Niño is still under debate. In the present study, a mode function ...
Holbrook, W. Steven; Fer, Ilker; Schmitt, Raymond W.; Lizarralde, Daniel; Klymak, Jody M.; Helfrich, L. Cody; Kubichek, Robert (American Meteorological Society, 2013-08)Seismic images of oceanic thermohaline finestructure record vertical displacements from internal waves and turbulence over large sections at unprecedented horizontal resolution. Where reflections follow isopycnals, their ...
Alexander, Michael A.; Seo, Hyodae; Xie, Shang-Ping; Scott, James D. (American Meteorological Society, 2012-05-15)The recently released NCEP Climate Forecast System Reanalysis (CFSR) is used to examine the response to ENSO in the northeast tropical Pacific Ocean (NETP) during 1979–2009. The normally cool Pacific sea surface temperatures ...