BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Parameterisation of small-scale random forcing in β-plane turbule
 nce - Gavin Esler (University College London)
DTSTART:20240416T103000Z
DTEND:20240416T113000Z
UID:TALK215845@talks.cam.ac.uk
DESCRIPTION:In two-dimensional turbulent flows subject to small-scale rand
 om forcing and dissipation\, it is sometimes possible to make successful p
 redictions for the structure of emergent large-scale coherent structures\,
  or condensates\, using a relatively simple closure for the eddy-driven mo
 mentum fluxes. In the case of the classical problem of zonal jet formation
  on a beta-plane\, however\, such an approach has hitherto had limited suc
 cess. Here a closure approach suggested by Srinivasan and Young is develop
 ed and investigated with a view to understanding what is required for a su
 ccessful resolution of the beta-plane problem. The key missing ingredient 
 is found to be that distinct secondary instabilities develop on both the e
 astward and westward jets\, and these lead to the growth and equilibration
  of&nbsp\; waves on the jet scale. Momentum fluxes due to these secondary 
 waves then play a key role in the momentum balance of the equilibrated jet
 s. Parameterised calculations in which the random forcing is replaced by a
  deterministic forcing based on Srinivasan-Young are shown to result in ne
 ar-identical jet structures to numerical calculations of the full problem.
  A limitation\, however\, is that the parameterised calculations must them
 selves be eddy-permitting (i.e. not purely zonal) in order that secondary 
 instabilities can develop.
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR