1. LASP seminar, 18 October 2011, Boulder
Multi-Model Comparisons of the Sensitivity of the Atmospheric Response to the SORCE Solar Irradiance Data Set within the SPARC-SOLARIS Activity
K. Matthes (1,2), J.D. Haigh (3), F. Hansen (1,2), J.W. Harder (4), S. Ineson (5), K. Kodera (6,7), U. Langematz (2), D.R. Marsh (8), A.W. Merkel (4), P.A. Newman (9), S. Oberländer (2), A.A. Scaife (5), R.S. Stolarski (9,10), W.H. Swartz (11)
(1) Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum (GFZ), Potsdam, Germany; (2) Freie Universität Berlin, Institute für Meteorologie, Berlin, Germany; (3) Imperial College, London, UK; (4) LASP, CU, Boulder, USA; (5) Met Office Hadley Centre, Exeter, UK; (6) Meteorological Research Institute, Tsukuba, Japan; (7) STEL University of Nagoya, Nagoya, Japan; (8) NCAR, Boulder USA; (9) NASA GSFC, Greenbelt, USA; (10) John Hopkins University, Baltimore, USA; (11) JHU Applied Physics Laboratory, Laurel, USA

2. Outline Introduction/Motivation: Solar influences on climate
SOLARIS project and objectives
Uncertainty in solar irradiance data
Preliminary results from the multi-model comparison
Summary
Outlook

3. Introduction/Motivation: natural vs. anthropogenic climate factors
IPCC (2007)

4. Solar Influences on Climate
Reviews in Geophysics 2010
(open access sponsored by SCOSTEP)
Introduction
2. Solar Variability
Causes of TSI variability
Decadal-scale solar variability
Century-scale variability
TSI and Galactic cosmic rays
3. Climate Observations
Decadal variations in the stratosphere
Decadal variations in the troposphere
Decadal variations at the Earth’s surface
Century-scale variations
4. Mechanisms
TSI UV
Centennial-scale irradiance variations
Charged particle effects
5. Solar Variability and Global Climate Change
6. Summary / Future Directions

5. Solar Variability (1975-2010) Sunspot number F10.7 cm flux
Magnesium ii
Open solar flux
Galactic cosmic ray counts
Total solar irradiance
Geomagnetic Ap index
Gray et al. (2010)

6. 30hPa Heights North Pole vs. F10.7 cm flux - February
Climate Observations
....beginning with the pioneering work of Karin Labitzke and Harry van Loon
Correlations F10.7cm flux vs. 30hPa temperatures in July
30hPa Heights North Pole vs. F10.7 cm flux - February
Labitzke,
Labitzke and van Loon ....

7. Tropospheric winds Schematic of Jetstream NCEP Zonal Mean Wind (m/s)
( )
11-year Solar Signal (Max-Min)
blocking events => cold winds from the east over Europe
blocking events longer lived for solar minima (Barriepedro et al., 2008)
Haigh, Blackburn, Simpson

8. Observed Annual Mean Solar Signal in Ozone (%/100 f10
Observed Annual Mean Solar Signal in Ozone (%/100 f10.7) and Temperature (K/100 f10.7)
SAGE I/II Data ( )
SSU/MSU4 ( )
+2%
+1K
Randel et al. (2009)
95% significant
Randel and Wu (2007)
Solar Maximum:
More UV radiation => higher temperatures
More ozone => higher temperatures

9. 11-year Solar Signal (Max-Min) Composites
Climate Observations
11-year Solar Signal (Max-Min) Composites
Dec/Jan/Feb
Sea surface temperature:
11 Max peak years
Precipitation:
3 Max peak years
van Loon, Meehl, White

10. Surface Temperatures: IPCC
Solar variations cannot explain observed 20th century global temperature changes
long-term trend in solar activity appears to be decreasing, as we come out of the current ‘Grand Maximum’
anthropogenic + natural forcings
natural forcings only

11. Climate Observations: Summary
Lots of examples of 11-yr solar influence in the stratosphere, troposphere and at the surface (e.g., temperatures (LvL), SSTs, mean sea level pressure, zonal and vertical winds, tropical circulations: Hadley, Walker, annular modes, clouds, precipitation), but predominantly regional response and sporadic in time.
No evidence that solar variations are a major factor in driving recent climate change; if anything, radiative forcing looks as though it is reducing as we possibly come out of the current grand maximum.
BUT, as we start to predict climate on a regional basis, it will be important to include solar variations in our models.

12. Climate Models:
Majority of coupled ocean-atmosphere climate models include only total solar irradiance (TSI) variations, i.e. the so-called ‘bottom-up’ mechanism.
More recent climate models now include the ‘top-down’ mechanism via the stratosphere.
Some specialist models also now include charged particle effects, e.g. energetic particle fluxes, solar proton events etc.

13. Mechanisms: Sun - Climate
Gray et al. (2010)

14. “Top-down mechanism” based on Kodera and Kuroda (2002)
Gray et al. (2010)

15. (response to stratospheric changes)
„Top-down“: Dynamical Interactions and Transfer to the Troposphere 10-day mean wave-mean flow interactions (Max-Min) u
EPF
Die Differenzen sind vom QBO Ost Experiment (vgl. Abb.12 Matthes et al. (2004)), das habe ich aber extra nicht hervorgehoben.
Stratospheric waves
(direct solar effect)
Tropospheric waves
(response to stratospheric changes)
Matthes et al. (2006)

16. Modeled Signal near Earth Surface Monthly mean Differences geop
Modeled Signal near Earth Surface Monthly mean Differences geop. Height (Max-Min) – 1000hPa + -
+2K ΔT
Zur besseren Übersicht und zum Zeigen der statistischen Signifikanzen noch einmal die Monatsmittel. Habe mich dazu entschlossen, nicht die Abb. Von Yuhji zu zeigen, sondern nur auf das Hauptergebnis hinzuweisen.
Matthes et al. (2006)
Significant tropospheric effects (AO-like pattern) result from changes in wave forcing in the stratosphere and troposphere which changes the meridional circulation and surface pressure

17. SPARC-SOLARIS
Goal: investigate solar influence on climate with special focus on the importance of middle atmosphere chemical and dynamical processes and their coupling to the Earth‘s surface with CCMs, mechanistic models and observations
Activities:
detailed coordinated studies on „top-down“ solar UV and „bottom-up“ TSI mechanisms as well as impact of high energy particles
solar irradiance data recommendations
(CCMVal, CMIP5)
SOLARIS

18. SOLARIS Activities
2006
2010
regular workshops: 2006 (Boulder, CO/USA), 2010 (Potsdam, Germany),
8-12 Oct 2012 (Boulder, CO/USA)
side meetings: 2005 (IAGA conference, Toulouse, France), 2008 (SPARC,
Bologna, Italy), 2010 (SCOSTEP, Berlin, Germany),
2011 (IUGG, Melbourne, Australia)
new website:

19. SOLARIS Objectives
What is the characteristic of the observed solar climate signal?
What is the mechanism for solar influence on climate? (dynamical and chemical response in the middle atmosphere and its transfer down to the Earth’s surface)
How do the different natural and anthropogenic forcings interact? (solar, ENSO, QBO, volcanoes, CO2)

20. SOLARIS Experiments and Analyses
Coordinated model runs to investigate aliasing of different factors in the tropical lower stratosphere
Coordinated model runs to study the uncertainty in solar forcing
Analysis of CMIP5 simulations

21. Uncertainty in Solar Irradiance Data
Solar Max-Min
Lean vs. Krivova
Haigh et al., Nature (2010)
Lean vs. SIM/SORCE
Lean et al. (2005)
Krivova et al. (2006)
larger variation in Krivova data in and nm range
SORCE measurements from 2004 through 2007 show very different spectral distribution (in-phase with solar cycle in UV, out-of-phase in VIS and NIR)
=> Implications for solar heating and ozone chemistry

22. 1. Compare Existing Model Runs Participating Models
Caveat: all the models used a slightly different experimental setup, so it won’t be possible to do an exact comparison

23. Differences in Experimental Setup
NRL SSI
SORCE (SOLSTICE&SIM)
ozone
EMAC-FUB
2004 & 2007 No
GEOS-5 CCM
Yes
HadGEM -
Scaled up to
Max & Min
only UV ( nm)
IC2D
WACCM
2007

24. Experimental Design Time series of F10.7cm solar flux „solar max“ 2004
2004:
“solar max”
(declining phase of SC23)
2007:
“solar min”
(close to minimum of SC23)
„solar min“ 2007

25. January Mean Differences (25N-25S)
Shortwave Heating Rate (K/d)
Temperature (K)
Pressure (hPa)
Pressure (hPa)
Height (km)
Height (km)
NRL SSI
SORCE
larger shortwave heating rate and temperature differences for SORCE than NRL SSI data
FUB-EMAC and HadGEM only include radiation, not ozone effects

26. January Mean Differences (25N-25S)
Ozone (%)
Temperature (K)
Pressure (hPa)
Pressure (hPa)
Height (km)
Height (km)
NRL SSI
SORCE
larger ozone variations below 10hPa and smaller variations above for
SORCE than NRL SSI data
height for negative ozone signal in upper strat. differs between models

27. Shortwave Heating Rate Differences January (K/d)
EMAC-FUB
GEOS
HadGEM
IC2D
WACCM
NRL SSI
SORCE
NRL SSI shortwave heating rates: 0.2 to 0.3 K/d
SORCE shortwave heating rates: to >1.0 K/d (3x NRL SSI response)

28. Temperature Differences January (K)
EMAC-FUB
GEOS
HadGEM
IC2D
WACCM
NRL SSI
NRL SSI temperatures: 0.5 to 1.0 K (stratopause)
SORCE temperatures: to 4.0 K (4-5x NRL SSI response)
colder polar stratosphere
SORCE

29. Ozone Differences January (%)
EMAC-FUB
GEOS
HadGEM
IC2D
WACCM
NRL SSI
SORCE
larger ozone variations below 10hPa and smaller variations above for
SORCE than NRL SSI data
height for negative ozone signal in upper strat. differs between models

30. Zonal Wind Differences January (m/s)
EMAC-FUB
GEOS
HadGEM
IC2D
WACCM
NRL SSI
SORCE
consistently stronger zonal wind signals for SORCE than NRL SSI data
wind signal in SORCE data characterized by strong westerly winds at polar latitudes, and significant and similar signals in NH troposphere

31. SORCE Wind Differences NH Winter
EMAC-FUB
GEOS
HadGEM
IC2D
WACCM
Dec
Jan
Feb

32. SORCE Geopot. Height Differences January (gpdm)
EMAC-FUB
GEOS
HadGEM
WACCM
500 hPa
NAO/AO positive signal during solar max strongest for HadGEM and WACCM
100 hPa
10 hPa

33. Solar Max: NAO positive (high index)
Solar Cycle and the NAO
Solar Max: NAO positive (high index)
Colder stratosphere => stronger NAO,
i.e. stronger Iceland low, higher
pressure over Azores
amplified storm track
mild conditions over northern
Europe and eastern US
=> dry conditions in the mediterranean

34. Solar Min Surface Pressure Signal
Model (HadGEM) Observations (Reanalyses)
25 (50%) of
interannual
standard deviation
90 (95%)
significances
Ineson et al. (2011)

35. Solar Cycle and the NAO Solar Min: NAO negative (low index)
Solar Max: NAO positive (high index)
Matthes (2011)

36. Summary
Consistently larger amplitudes in 2004 to 2007 in solar signals for SORCE than for NRL SSI data in temperature, ozone, shortwave heating rates, zonal winds and geopotential heights
Larger ozone variations below 10hPa and smaller variations above for SORCE than NRL SSI data; height for negative ozone signal in upper stratosphere differs between models
Solar cycle effect on AO/NAO contributes to substantial fraction of typical year-to-year variations and therefore is a potentially useful source of improved decadal climate predictability (Ineson et al. (2011))
 Results for the SORCE spectral irradiance data are provisional because of the need for continued degradation correction validation and because of the short length of the SORCE time series which does not cover a full solar cycle

37. Outlook
Next step: coordinated sensitivity experiments for a typical solar max (2002) and solar min (2008) spectrum from the NRL SSI and the SORCE data to investigate the atmospheric and surface climate response between the models in a more consistent way
=> White paper until early December, experiments to be started early 2012 in order to be ready for the SOLARIS/HEPPA workshop 8-12 October 2012 here in Boulder!

38. Thank you very much!
Estes Park/RMNP,

39. Extra slides

40. SOLARIS and Links to HEPPA
Objective of joined SOLARIS-HEPPA Intercomparison Working group: 1. join activities on „Solar Influence on Climate“ and enhance visibility
2. recommendation which processes to include in future climate studies (next IPCC round)
SOLARIS
HEPPA

41. Solar Variability (1600-2010) Total solar irradiance
Galactic cosmic ray counts
Geomagnetic aa index
Aurora sightings
Mention „modern maximum“
Sunspot number
Beryllium10 concentrations

42. Climate Observations: Carbon-14 (Solar Proxy)
ice-rafted debris N. Atlantic: solar min greater sea ice extent
sedimentary deposition in Alaska: wetter, colder conditions
stalagmite properties in Oman: reduced monsoon precipitation