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PRODID:https://murmitoyen.com/events/vanille/udem/
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UID:69e0440ab18b0
DTSTAMP:20260415T220602
DTSTART:20140123T113000
SEQUENCE:0
TRANSP:OPAQUE
DTEND:20140123T123000
URL:https://murmitoyen.com/events/vanille/udem/detail/364210
LOCATION:Université de Montréal - Pavillon Roger-Gaudry\, 2900\, chemin d
 e la Tour\, Montréal\, QC\, Canada\, H3T 1J6
SUMMARY:The SATIRE-S spectral solar irradiance data set and limits in under
 standing the effect of irradiance on stratospheric ozone
DESCRIPTION:Conférence de William Ball\, Imperial College London.Résumé
  Absorption of solar ultraviolet (UV) radiation by ozone is the main sour
 ce of heating in the stratosphere\, affecting the chemistry\, temperature 
 and dynamics of the atmosphere. Here\, I will (1) present a revised and up
 dated SSI dataset using the SATIRE-S model\, in the context of other irrad
 iance models and observations\, and (2) investigate the limits in our know
 ledge of how SSI may vary over the solar cycle (SC) by using stratospheric
  ozone observations and Bayesian inference. The new SATIRE-S SSI dataset s
 pans 1974 to 2009. I compare SATIRE-S with the NRLSSI model and SORCE/SOLS
 TICE observations. SATIRE-S and NRLSSI show similar SC changes below 250 n
 m. However\, SATIRE-S show almost double the change in flux as NRLSSI betw
 een 250 and 310 nm\, but less than half that of SORCE/SOLSTICE. These vari
 ous UV changes lead to different ozone responses in the stratosphere. Inst
 ead of just comparing the ozone response to these different SSI datasets w
 ith ozone observations\, I pose the question: Can the observed SC change i
 n stratospheric ozone constrain the allowed range of solar UV changes? To 
 answer this\, I first show that the response of equatorial stratospheric o
 zone to SC changes in UV can be estimated using a simple linear approximat
 ion. This then allows a Bayesian formalism to show that one cannot disting
 uish between different SSI datasets using current estimates of ozone chang
 es. The Bayesian approach presented here could be developed to investigate
  other datasets and provide a better understanding of both variations in S
 SI and the atmospheric response to it.Présentée par le Groupe Astronomie
  et astrophysique du Département de physique de l'Université de Montré
 al. Cette conférence est destinée à des spécialistes dans le domaine d
 e l'astrophysique et sera donnée en anglais.
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