solar cycle effects on stratospheric temperature
DESCRIPTION
The University of Reading. Solar cycle effects on stratospheric temperature. Strat Hour - July 05, 2006. Steve Rumbold Keith Shine, Lesley Gray Charlotte Pascoe (CASE, RAL). Picture: http://cloud1.arc.nasa.gov/crystalface/. Effect of 11 year Solar Cycle. - PowerPoint PPT PresentationTRANSCRIPT
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Steve Rumbold
Keith Shine, Lesley Gray Charlotte Pascoe (CASE, RAL)
Picture: http://cloud1.arc.nasa.gov/crystalface/
Strat Hour - July 05, 2006
The University of Reading
Solar cycle effects on stratospheric temperature
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Effect of 11 year Solar Cycle• Two main ways to
affect stratospheric temperatures– Direct effect of flux
change– Effect of resultant
Ozone changes
• 0.1 – 0.15 % on total solar irradiance (TSI)
• However, large percentage effect in UV
Insert Ref.
Data: www.ngdc.noaa.gov/stp/SOLAR/
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How can the solar cycleinfluence the stratosphere?
• Large percentage effect in UV
• Effects shortwave heating (O2, O3)
Percentage change in spectral flux from solar min to max [data: Lean et al, 1997].
1. UV effect
2. Ozone effect
Percentage change in ozone from solar min to max determined from observations (annual mean) [data: SAGE satellite, Randel, 2005].
• Change in UV has effect on O3 concentrations
• This in turn has effect on heating
• Magnitude and distribution of change varies between studies
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Approach
Description of modelBlue = inputs, Pink = model,
Yellow = outputs
• Determine radiative component of solar cycle effect
• The model [Forster and Shine, 1997]: • Narrow band radiation code• Fixed Dynamical Heating (FDH)
i. The radiative response can be isolated.
ii. High spectral resolution radiative calculations can be performed.
iii. A large number of separate calculations can be run quickly.
• This has been used instead of a General Circulation Model (GCM) for three main reasons:
0)(
DTQt
T
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Spectral sensitivity experiment
(from Lean et al. 1997)
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Black line = Lean et al. 1997Grey = Lean 2005 range (1
Comparison of “classic” data with new study
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Test of influence of Mg II line
• To asses the importance of the Mg II line, three experiments were conducted with the FDH model:
i. Using actual solar cycle UV change (Black).ii. Same as i. but without Mg II line (Blue).iii.Just Mg II line change (Red).
• The Mg II line has moderate importance to total solar change. ~1/6 of total effect at 1 mbar.
• ii. and iii. sum linearly to reproduce i.
Oct, Equator
Investigating Mg II lineTemperature change due to the spectrally resolved irradiance changes.
Note: weird units[ K / (10nm) ]
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LW SW NETChange in
radiative heating(max minus min)
[ K / day ]
(or greater)
(or less)
Results from idealised ozone
change experiment
6%56 km
+5 km
-5 km1/e
1/e
“Minimum” =Climatology – 0.5 x change
“Maximum” =Climatology + 0.5 x change
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Temperature change(max minus min)
[ K ](Oct)
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A solar maximum minus minimum experiment
• Irradiance changes only
• Ozone changes only
• Combining the two
• Compare to other studies
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Irradiance Changes Only
Minimum = solar neutral spectra – 0.5 x change
Maximum = solar neutral spectra + 0.5 x change
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Ozone changes solar maximum minus minimum [ % ](annual mean)
SAGE I/II Regression – Randel (2005)
GISS – Shindell et al. (1999) Imperial College – Haigh (1994)
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Resulting FDH temperature changes
(solar maximum minus minimum [ K ] )
Shibata and Kodera, 2005Using GISS ozone
Shibata and Kodera, 2005Using Imperial ozone
Reading FDHMUsing SAGE I/II ozone
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ERA-40 ReanalysisCrooks & Gray (2005)
Reading FDHM(SAGE ozone changes+ UV irradiance changes)
Temperature change ( solar maximum minus minimum [ K ] )(annual mean)
0.5 K 0.5 K
1.8 K
1.8 K
0.5 K
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Ozone effect vs. irradiance effectBold line “50/50”. Dotted lines “irradiance wins”. Solid lines “ozone wins”