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CATEGORIES:Stokes Society\, Pembroke College
SUMMARY:Causes of Climate Change and the Role of the Sun -
  Professor Joanna Haigh
DTSTART;TZID=Europe/London:20160224T210000
DTEND;TZID=Europe/London:20160224T220000
UID:TALK63754AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/63754
DESCRIPTION:Do changes in the Sun affect the Earth’s climate? 
 Variations in the Earth’s orbit clearly have a maj
 or effect\, controlling diurnal and seasonal cycle
 s as well as the onset of ice ages\, but what abou
 t the impact of intrinsic variability within the S
 un? Observations of sunspots date back to at least
  the 2nd century BC\, and so have speculations tha
 t sunspot numbers are related to weather\, althoug
 h many such claims were statistically dubious. Now
 adays\, the need to distinguish natural from anthr
 opogenic causes of changes in climate has placed n
 ew emphasis on quantifying and understanding any s
 uch relationship. Another consideration in the pas
 t was the lack of evidence of any measureable vari
 ation in the Sun’s energy output. The advent of sa
 tellite measurements of solar irradiance\, however
 \, together with the collation of well-calibrated 
 records of atmospheric and oceanographic parameter
 s\, have enabled considerable progress to be made 
 in establishing evidence of solar-climate links on
  a range of timescales. Our research shows that wh
 en the Sun is more active the atmosphere responds 
 by a warming of the stratosphere in low latitudes 
 but that the predominant signal in the lower atmos
 phere appears in mid-latitudes. Associated with th
 is the jet streams weaken and move polewards\, alo
 ng with the mid-latitude storm-tracks. We have fou
 nd that an important factor driving this response 
 is the absorption of solar UV radiation in the str
 atosphere and we have been able to identify a mech
 anism for dynamical coupling between the stratosph
 ere and the atmosphere below.Over the past few yea
 rs some satellite measurements have suggested that
  variations at UV wavelengths are larger than prev
 iously understood. I will discuss the implications
  of these spectral variations for the stratosphere
  and describe how measurements of stratospheric oz
 one might be used synergistically with those of so
 lar spectral irradiance to improve knowledge of th
 e variations in both.
LOCATION:Nihon Room\, Pembroke College
CONTACT:Jamie Fox
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