BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:On convective penetration of a buoyant plume into a stably stratif
 ied layer - Charles Powell\, DAMTP
DTSTART:20260527T130000Z
DTEND:20260527T140000Z
UID:TALK246601@talks.cam.ac.uk
CONTACT:Anna Walczyk
DESCRIPTION:We use an idealised fluid dynamical model to explore the proce
 sses that control moisture transport by convective overshoots in the tropi
 cal tropopause layer\, which influences stratospheric water vapour content
  globally. Numerical simulations have been performed using realistic and c
 omplex meteorological models containing many physical processes\, but thes
 e are computationally expensive and challenging to interpret. We attempt t
 o gain insight into this process by considering large eddy simulations of 
 a simple fluid dynamical problem representative of the environment\, in wh
 ich overshooting tops are represented by the penetration of a buoyant plum
 e into a strongly stably stratified layer. We study turbulent mixing in th
 e flow\, explore internal wave generation\, and construct a simplified mod
 el of convective hydration in the atmosphere.\n\nThe talk is composed of t
 hree parts. First\, we introduce a novel method for diagnosing transport o
 f a passive tracer in turbulent flows using a 2D phase space where mixing 
 can be interpreted geometrically and separated into three mixing 'stages'\
 , each corresponding with coherent regions of the plume. We then explore t
 he generation of internal gravity waves\, showing that existing theories c
 annot explain the observed gravity wave spectra in our numerical simulatio
 ns. Using Dynamic Mode Decomposition and ray tracing\, we show that waves 
 originate inside the turbulent plume\, and are modified as they propagate 
 into the environment\, yielding the observed wave spectrum. Finally\, we f
 ormulate a minimal moisture scheme that represents only the essential phys
 ical processes that contribute to hydration of the TTL. Here we focus on t
 he influence of large-scale vertical shear in the stratified layer\, which
  increases moisture transport by enhancing turbulent mixing via critical-l
 ayer wave breaking and shear instabilities.
LOCATION:LT6
END:VEVENT
END:VCALENDAR