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SUMMARY:Internal wave packet tunnelling across a thermohaline staircase - 
 Bruce Sutherland (University of Alberta)
DTSTART:20240514T150000Z
DTEND:20240514T160000Z
UID:TALK216913@talks.cam.ac.uk
DESCRIPTION:Due to double diffusive processes below the thermocline in the
  Arctic Ocean\, vertical density profiles exhibit a staircase structure in
  which successive layers of near-uniform density are separated by sharp de
 nsity&nbsp\;jumps. &nbsp\;Earlier work [Sutherland\, PR Fluids (2016)] the
 oretically predicted the transmission and reflection of a vertically propa
 gating internal gravity wave incident from above upon a density staircase 
 with an arbitrary&nbsp\;number of steps. &nbsp\; That work assumed a plane
  incident wave\, being monochromatic in wavenumber and frequency. &nbsp\;F
 or waves with given frequency\, the transmission coefficient exhibited a s
 eries of spikes&nbsp\;depending upon the depth of steps relative to the ho
 rizontal wavelength. &nbsp\;Here we use numerical simulations to examine t
 he transmission of a vertically propagating internal wavepacket that inter
 acts transiently with&nbsp\;a staircase. &nbsp\;Rather than exhibit succes
 sive transmission spikes\, the simulations show a smooth transition betwee
 n perfect and zero transmission as the relative step size increases. &nbsp
 \;This results from internal waves&nbsp\;exciting leaky internal modes of 
 the staircase that retransmit waves above and below the staircase slowly o
 ver time\, as can be predicted by theory.
LOCATION:Seminar Room 2\, Newton Institute
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