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SUMMARY:On acoustic-gravity waves in arctic zones with elastic ice-sheets 
 - Usama Kadri (Cardiff University\; Massachusetts Institute of Technology)
DTSTART:20171006T131500Z
DTEND:20171006T140000Z
UID:TALK84441@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:We present an analytical solution of the boundary value proble
 m of propagating acoustic-gravity waves generated in the ocean by earthqua
 kes or ice-quakes in arctic zones. At the surface\, we assume elastic ice-
 sheets of a variable thickness\, and show that the propagating acoustic-gr
 avity modes have different mode shape than originally derived by Ref. [1] 
 for a rigid ice-sheet settings. Computationally\, we couple the ice-sheet 
 problem with the free surface model by Ref. [2] representing shrinking ice
  blocks in realistic sea state\, where the randomly oriented ice-sheets ca
 use inter modal transition at the edges and multidirectional reflections. 
 We then derive a depth-integrated equation valid for spatially slowly vary
 ing thickness of ice-sheet and water depth. Surprisingly\, and unlike the 
 free-surface setting\, here it is found that the higher acoustic-gravity m
 odes exhibit a larger contribution. These modes travel at the speed of sou
 nd in water carrying information on their source\, e.g. ice-sheet motion o
 r submarine earthquake\, providing various implications for ocean monitori
 ng and detection of quakes. In addition\, we found that the propagating ac
 oustic-gravity modes can result in orbital displacements of fluid parcels 
 sufficiently high that may contribute to deep ocean currents and circulati
 on.
LOCATION:Seminar Room 1\, Newton Institute
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