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SUMMARY:Our current understanding of solar irradiance and its effect on st
 ratospheric ozone - Dr William Ball (Imperial)
DTSTART:20140616T131500Z
DTEND:20140616T143000Z
UID:TALK51289@talks.cam.ac.uk
CONTACT:Dr Amanda Maycock
DESCRIPTION:Absorption of solar ultraviolet (UV) radiation by ozone is the
  main source of heating in the stratosphere\, affecting the chemistry\, te
 mperature and dynamics of the atmosphere. Knowing (i) by how much the Sun 
 varies spectrally on decadal and longer timescales and (ii) how it interac
 ts with the Earth are key to understanding its influence on our climate. \
 n\nHere\, I will review the present state of the art in observations and m
 odels of solar irradiance. I will focus on comparing the SATIRE-S model wi
 th the NRLSSI model and SORCE observations. Together\, these datasets enco
 mpass the full range of observed and modelled spectral solar irradiance (S
 SI) SC changes. SATIRE-S and NRLSSI show similar SC changes below 250 nm. 
 However\, SATIRE-S show almost double the change in flux as NRLSSI between
  250 and 310 nm\, but less than half that of SORCE/SOLSTICE. These various
  UV changes lead to different ozone responses in the stratosphere.\n\nI wi
 ll provide a test to show how the different SC SSI changes affect equatori
 al stratospheric ozone. Instead of just comparing the modelled ozone respo
 nse to these different SSI datasets with ozone observations\, I pose the q
 uestion: can the observed SC change in stratospheric ozone constrain the a
 llowed range of solar UV changes? I will show how this can be done using a
  simple linear approximation combined with a Bayesian formalism. The appro
 ach presented here could be extended to provide a better understanding of 
 both variations in SSI and the atmospheric response to it.
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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