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SUMMARY:Driving upwelling by heating the lower stratosphere - Alison Ming 
 (DAMTP)
DTSTART:20170512T150000Z
DTEND:20170512T160000Z
UID:TALK72343@talks.cam.ac.uk
CONTACT:Doris Allen
DESCRIPTION:A feature of the time averaged tropical lower stratospheric up
 welling is the double peak structures centred near 70 hPa and 20&deg\; N-S
  which have previously been noted in observational datasets.\nHowever\, th
 e corresponding structures in diabatic heating rates are not related to lo
 cal temperature\nanomalies as would be the case if they were relaxational 
 in nature. We will first demonstrate that\nthe enhanced diabatic heating n
 ear the centre of these peaks relative to the Equator arises predominantly
  from the meridional structure in ozone concentrations. We then suggest th
 at the primary\ncause of the peaks in upwelling is the externally imposed 
 part of the radiative heating field which\nis able to change the wave fiel
 d. This motivates the second part of this study in which a scaling\nargume
 nt shows that an externally imposed zonally symmetric heating can indeed d
 rive steady-state\nupwelling provided that the wave force (required to sat
 isfy angular momentum constraints) is sufficiently sensitive to changes in
  the mean \nflow. The applicability of this regime to the observed double 
 peak structure is confirmed by experiments in a dry dynamical circulation 
 model. Similar arguments\nare then be applied to problem of the recently i
 dentified compensation between the driving of the\nBrewer-Dobson circulati
 on by resolved and parameterized waves.
LOCATION:MR2\, Centre for Mathematical Sciences\, Wilberforce Road\, Cambr
 idge
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