Stratospheric and tropospheric effects of solar activity

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Stratospheric and tropospheric effects of solar
activity

• K. Tourpali
• Lab. Of Atmospheric Physics
• Aristotle University of Thessaloniki, Greece
• CCMVal-2 PIs

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Questions

• How does the Sun influence natural climate
  variability?
• What is the role of the stratosphere - how does
  the exchange with the troposphere work?
• Which mechanisms (top-down, bottom-up) are
  important for solar influences on climate?
• Can climate models represent the observed
  signals?

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Observations

• Solar cycle variations in
• Stratosphere Temperatures and geopotential
  heights (Labitzke and van Loon)
• Sea surface temperatures, mean sea level
  pressures
• Winds Zonal, Vertical
• Tropical circulations Hadley, Walker
  circulation
• Mid / high latitude annular modes
• Clouds / precipitation

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Observations

• Solar cycle variations in
• Stratosphere Temperatures and geopotential
  heights (Labitzke and van Loon)
• Sea surface temperatures, mean sea level
  pressures
• Winds Zonal, Vertical
• Tropical circulations Hadley, Walker
  circulation
• Mid / high latitude annular modes, especially
  Arctic Oscilaltion
• Clouds / precipitation

Recent variability of the solar spectral
irradiance and its impact on climate modelling -
TOSCA WG1 Workshop, May 2012, Berlin
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SPARC CCMval Activity Solar signal in CCMVal-2
runs

• Simulation Ref-B1 Reproducing the past

transient run from 1960 - to the present All
forcings taken from observations
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(No Transcript)
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SPARC Report -Solar signal in CCMVal-2 runs
25N-25S The signal in upper stratosphere is
reasonably represented in models However, there
are large differences between CCMs But also
between observation data sets! possible aliasing
of signal ENSO, volcanoes
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SPARC Report - Solar signal in CCMVal-2 runs
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Climate Chemistry ModelsRef-B1 of CCMVal-2

• No solar cycle!
• GEOSCCM
• ULAQ
• UMUKCA-METO
• UMUKCA-UCAM
• UMETRAC

• AMTRAC3
• CAM3.5
• CCSRNIES
• CMAM
• CNRM-ACM
• E39CA ?? Gpz not available
• EMAC
• LMDZrepro
• MRI
• NiwaSOCOL
• SOCOL
• UMSLIMCAT
• WACCM

To compareEra-40 reanalysis
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Data and method of analysis

• Inputs from CCMs (monthly averages)
• Geopotential heights (3D)
• Zonal winds and temperature profiles (zonal
  means)
• Ozone total column and profile
• Analysis
• Regression analysis on zonal wind
• focus on northern hemisphere winter
• Annular mode in the Northern hemisphere winter
  (DJF)
• geopotential heights 850hPa, 500hPa,
  10hPa

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Linear regression

• Regression analysis on zonal wind
• focus on northern hemisphere winter

The autoregressive linear model in general form
Courtesy of Markus Kunze
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Annular mode analysis

• EOF analysis was performed on
• - detrended series of geopotential heights
• - separated in solar maximum and minimum years
• the 1st EOF pattern represents the Arctic
  Oscillation variability
• AO-index is the normalised leading PC
• Winter mean fields regressed onto this AO-index
• Correlation between the AO-index and zonal mean
  wind and zonal mean temp
• I have not touched ozone yet!

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zonal wind response
Nov Dec Jan Feb Mar
AMTRAC3 CMAM SOCOL WACCM
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Solar signal in AO modewinter 850 hPa
geopotential height
Era-40
AMTRAC
CMAM
meters
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Solar signal in AO modewinter 850 hPa
geopotential height
Era-40
SOCOL
WACCM
meters

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Solar signal in AO modewinter 500 hPa
geopotential height
Era-40
AMTRAC
CMAM

meters
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Solar signal in AO modewinter 500 hPa
geopotential height
Era-40
SOCOL
WACCM

meters
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Solar signal in winter AO modewinter 10 hPa
geopotential height

• Era-40
• Amtrac
• waccm

meters
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Arctic Oscillation

• Reanalysis clear difference between solar max
  and min years.
• A number of models with solar cycle variability
  reproduce this

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• What does a model with no SC show?

850 hPa
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Extension of the signal in the stratosphere
Correlation to zonal wind 850 mb AO index
Era-40
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Extension of the signal in the stratosphere
Correlation to zonal wind
amtrac3
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Summary (Conclusions not there yet!)

• Chemistry-Climate Models do represent the solar
  max vs min changes in the shape of AO
• How about the vertical extension of the signal?
• Do volcanic eruptions (or ENSO) disrupt the
  signal?

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And, more Questions!

• What are the differences in ozone and temperature
  if a new SSI forcing is used?
• Will the stratospheric-tropospheric signals show
  up if another SSI forcing is used? Stronger or
  weaker?
• Will we find a better comparison to observations?
  
• Will our current perception of mechanisms
  (top-down, bottom-up) change?

Recent variability of the solar spectral
irradiance and its impact on climate modelling -
TOSCA WG1 Workshop, May 2012, Berlin
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Thank you!