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SUMMARY:Contributed talk: Helioseismic imaging of supergranulation - Chris
  Hanson (New York University)
DTSTART:20221129T114500Z
DTEND:20221129T121500Z
UID:TALK192089@talks.cam.ac.uk
DESCRIPTION:The Sun has a convection conundrum. The outer 30% of the solar
  interior is known as the convection zone\, where in the simplistic pictur
 e: hot material from the base rises\, cools at the near surface and return
 s back into the interior. Theory and numerical calculations stipulate the 
 existence of a multi-scale regime of convection\; where horizontally large
  scale diverging flows dredge up hot material from the deep interior and s
 maller scale convection overturns material in the near-surface. In between
  these extreme scales should exist a spectrum of convective features. The 
 conundrum is that the existence of large scale convection (~100Mm) has elu
 ded observers\, and only two scales of convection exist: granulation (~1Mm
 ) and supergranulation (36Mm). While the properties of granulation are wel
 l replicated by numerical simulations\, not much is known about the depth 
 structure of supergranulation and what role this apparently preferred flow
  scale plays in solar convection. Using 3 years of high resolution spacecr
 aft data and local helioseismic mode coupling techniques\, we construct av
 erage supergranules ranging from 32 to 45~Mm in horizontal scale. Through 
 inversion methods\, we obtain the depth structure of these flows from the 
 helioseismic data. We also determine the surface structure (sound speed\, 
 density and magnetic field). In this talk I will present our results and d
 iscuss their implications for solar convection.\nCo-Authors: Srijan Das\, 
 Prasad Mani\, Shravan Hanasoge\, Katepalli Sreenivasan
LOCATION:Seminar Room 1\, Newton Institute
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