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

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

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

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

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)

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 ....

Tropospheric winds Schematic of Jetstream NCEP Zonal Mean Wind (m/s) (1979-2002) 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

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 (1979-2005) SSU/MSU4 (1979-2005) +2% +1K Randel et al. (2009) 95% significant Randel and Wu (2007) Solar Maximum: More UV radiation => higher temperatures More ozone => higher temperatures

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

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

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.

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.

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

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

(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)

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

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

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: http://sparcsolaris.gfz-potsdam.de

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)

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

Uncertainty in Solar Irradiance Data Solar Max-Min Lean vs. Krivova Haigh et al., Nature (2010) 2004-2007 Lean vs. SIM/SORCE Lean et al. (2005) Krivova et al. (2006) larger variation in Krivova data in 200-300 and 300-400nm 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

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

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 (200-320nm) IC2D WACCM 2007

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

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

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

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: 0.7 to >1.0 K/d (3x NRL SSI response)

Temperature Differences January (K) EMAC-FUB GEOS HadGEM IC2D WACCM NRL SSI NRL SSI temperatures: 0.5 to 1.0 K (stratopause) SORCE temperatures: 2.5 to 4.0 K (4-5x NRL SSI response) colder polar stratosphere SORCE

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

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

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

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

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

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

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

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

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!

Thank you very much! Estes Park/RMNP, 10-15-2011

Extra slides

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

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

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