Sun Climate Climate and Societal Impacts of Solar Variations

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Sun Climate Climate and Societal Impacts of
Solar Variations

• Caspar Ammann, NCAR

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Overview

• Climatic challenges and their expected societal
  impacts
• Could the continuous Sun-Climate link provide
  important insight?
• Pathways of solar impact on Earths Climate and
  Society
• What do we know about past solar impacts on
  climate / society?
• Potentials and pitfalls, incl. The Little Ice
  Age
• Medieval Climate Anomaly
• What did climate look like, what was unusual?
• Could it have been solar driven?
• Model challenges
• What is the signal of the 11-year cycle, how is
  it simulated?
• What are the requirements for climate models and
  solar forcing data?
• Summary Role of Sun for Climate Change impact
  research

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Climate Change Challenges Sea Level
Satellite Altimetry / Surface observations More
rapid ice loss in Antarctica than
anticipatedPaleo records and Models Loss of
sections of W-Antarctica in previous Interglacials
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Global Water Issues
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Scientific Challenges AR5
( 1 ) CLIMATE SENSITIVITY Long, multi-century
projections to study Carbon Cycle
Feedbacks, Sea Level Change

• ( 2 ) REGIONAL DYNAMICS Very high-res
  simulations of the next 20-30 years for
  regional prediction

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Lessons from the Sun?

• Eddy 1976 Sun Climate link

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Pathways of solar impact on Climate

• Direct radiative influence of total energy
  change
• Indirect radiative effects through spectral
  variations
• Indirect effects through Atmospheric Dynamics
  and possibly change in coupled variability

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Direct radiative effects
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Indirect radiative effects through spectral
changes Ozone
MgII
Temp
Strat O3
Tot. O3
Marsh et al. 2008 - WACCM
Hood 1997 Observations (de-seasonalized)
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Solar Signal in NCEP/NCAR-Reanalysis Data
All years
QBO-E
Important imprint on anatural Mode of
Variability and Weather-noise NAO/AO
QBO-W
Geopot. Height Correlation Labitzke et al., 2006
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What data do we have about past effects of the
Sun on Climate and Society?

• Tree-Rings as climate indicators
• Two examples of identified solar impact
• Dangerous potential pitfalls

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What are tree rings?
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How do we know the date so precisely?
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Effect of High Solar Activity on the Western
Drought?Apparently consistent Short- and
Long-term Response
Late Medieval High Solar?
22-yr Drought Cycle back to AD 800
Cook et al. 2004
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Altai Mountains Ice Core Data
Ice Core Data (Schwikovski 2009)
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Hidden Dangers Superposition Sun and Volcanoes
Solar
Volcanic
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Medieval Climate Anomaly

• What did climate look like?
• Could it have been solar driven?

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Medieval Time Sparse record

• 1000 AD
• 1500 AD
• 1750 AD

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Vikings in Greenland / N-America
Settlements in Greenland and NE North America
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North America Mega Droughts

• Solar related?
• What other factorcould have suchlong timescales?

McDonald 2008
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Effect of High Solar Activity on the Pacific
Calibration 11-yr Cycle Signal (only solar max)
SST anomalies (1856-2004)
Precip. anomalies
Van Loon et al. 2007
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Solar Signal?(decadal/centennial?)
Solar effects in the Pacific Dynamics?
Volcanic effect(interannual)
Cobb et al., 2002
Adams et al., 2003
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C-Z Model with full solar and volcanic forcing
Low-freq. Solar, high-freq. Volcanic
Ensemble mean Nino3 (100 realizations of CZ model)
Palymra coral isotopes (standardized to have same
mean and standard deviation as Nino3 composite
series)
40 year smooth
Mann et al., 2003
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NCAR CCSM 3.0
IPCC AR4 Models Surface Temperatures Solar
11-year Cycle Max - Climatology
GFDL 2.1
GISS e_h

• MICRO med-res

Source Van Loon, Meehl, Arblaster
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Pacific SST as imposed driverWave pattern not
quite right far field
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Challenges for Models
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New Solar Module for Climate Studies for CCSM4
and WACCM

• Goals of new implementation
• Unified and consistent Solar input for CAM and
  WACCM
• Flexible module to accommodate various solar
  specifications path for future replacement of
  current data input by physical model of the Sun
• Independence from Radiative Transfer code base
• Realistic solar variability representation
  through unrestricted spectral and temporal
  resolution of (CAM4 / WACCM)
• Consistent information for radiative transfer
  and photolysis (WACCM)
• Improved accuracy in new radiative transfer code
  of CAM4 (RRTMG)
• Currently available data
• Judith Lean TSI for 1610-2008
• Judith Lean spectral data (1nm resolution) for
  1610-2008

• New definitions developed by CCSM and WACCM
  (alphabetically) C. Ammann, W. Collins, A.
  Conley, B. Eaton, J.F Lamarque, D. Marsh, F. Vitt

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Radiation Package (RRTMG or CAMRT)
Photolysis Package
Scale Factors on each band
Photon Fluxes
Solar Variability Coupler
Eventually Physical Solar Model
Flux on Radiation and Photolysis Boundaries
Spectrally Resolved Flux
File Data TSI Or Time Evolving Spectrum
Solar Specification
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11 Year Solar Cycle in Atmosphere
Van Loon Shea., 1999
Coughlin Tung, 2004
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Observations vs Model (even WACCM)
EMD NCEP EMD WACCM (incl ozone)
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New Solar Time Series for 20th Century Is it good
enough for regional prediction?
Changes AR5 from AR4 (1) Smaller Trend!
(2) New TSI Level
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Prediction Future Regional Moisture
Africa / Sahel Huge Uncertainty
US-Southwest Predictions Mega Drought
Drought and Heat Waves
20th century
21st century
Seager et al. 2007
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Summary I

• Solar irradiance variability has some, but small
  impact on the global mean temperature
• Indirect effects through spectral radiation and
  its modulation of the upper and middle atmosphere
  might be very important for a correct dynamical
  response to solar forcing
• Climate models need to be tested for minimal
  requirements to properly represent full
  atmospheric response that guides climate
• How important is high-temporal freq. variation?
• Progress is being made, but we are not there yet

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Summary II

• There is a need for a solid full atmospheric data
  assimilation product that allows for the
  identification of the 11-year solar cycle
• Surface records need to be analyzed for
  systematic/continuous solar impact
• Spectral solar irradiance data is needed that are
  linked to solar activity (11yr, Maunder-type)
• Define benchmark-type experiments for GCMs on
  decadal to century scale solar impact to test
  their ability to reproduce regional response

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THANK YOU !