1. SPARC SOLARIS & HEPPA Intercomparison Activities: Overview of SOLARIS Activities WCRP Open Science Conference 24-28 October 2011 Denver, CO, USA Session C7:Atmospheric Composition and Forcings, Poster M07B Motivation/Introduction The importance of solar forcing on climate has now been recognized. However, the atmospheric solar signal and its transfer mechanism(s) remain still uncertain. To address these questions, an international working group SOLARIS (Solar Influence Study for SPARC) was created to clarify the effects of 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 state-of-the art chemistry-climate models (CCMs) as well as mechanistic models and observations. We foster and initiate detailed studies on the "top-down" solar UV and the "bottom-up" TSI mechanisms, as well as on the impact of high-energy particles. In addition, SOLARIS aims to provide a platform for the coordination and discussion of solar-related studies. This includes recommendations for the solar irradiance and solar proton flux data used to drive middle atmosphere and climate models within e.g. the SPARC-CCMVal initiative and the CMIP5 simulations as well as collaborations with a number of other programs and groups such as the initiatives SPARC CCMVal, SPARC DynVar SPARC-DynVar, the High-Energy Precipitating Particles in the Atmosphere (HEPPA), the EU COST project: "Towards a better assessment of the impact of solar variability on the Earth's climate", as well as Task 1 of the programme SCOSTEP CAWSES II (Climate and Weather of the Sun-Earth System).CCMValDynVarSCOSTEP CAWSES II Katja Matthes 1,2, Kunihiko Kodera 3,4, and the SPARC SOLARIS Consortium (contact: matthes@gfz-potsdam.de) 1 Helmholtz Center Potsdam, GFZ German Center for Geosciences, Germany; 2 Institut für Meteorologie, Freie Universität Berlin, Germany; 3 STEL Nagoya University, Nagoya, Japan; 4 Meteorological Research Institute, Tsukuba, Japan Participating Groups Objectives Univ. Tokyo/Japan: Shingo Watanabe, M. Takahashi, Yosuke Yamashita Kyushu University/Japan: Toshihiko Hirooka MRI/Japan: Kiyotaka Shibata, Yuhji Kuroda, Kuni Kodera FUB/Germany: Ulrich Cubasch, Thomas Spangehl, Ulrike Langematz, Anne Kubin, Sophie Oberländer, Karin Labitzke GFZ/FUB Germany: Katja Matthes, Christian Blume, Felicitas Hansen, Christof Petrick KIT Karlsruhe/Germany: Thomas Reddmann MPI-Met/Germany: Hauke Schmidt GFDL/USA: John Austin University of California, Davis/USA: Terry Nathan San Jose State University/USA: Eugene Cordero GISS/USA: Drew Shindell, David Rind NCAR/USA: Dan Marsh, Rolando Garcia, Gerald Meehl Univ. Toronto/Canada: Victor Fomichev Univ. Thessaloniki/Greece: Klarie Tourpali Imperial College London/UK: Joanna Haigh University of Oxford/UK: Lesley Gray Service d' aéronomie Paris/France: Philippe Keckhut, Slimane Bekki, Francois Lott, Frank Lefevre PMOD/WRC, Davos/Switzerland: Eugene Rozanov, Tatiana Egorova University of Madrid/Spain: Natalia Calvo, Gabriel Chiodo Bodeker Scientific/New Zeadland: Greg Bodeker Central Aerological Observatory/Russia: Alexei Krivolutsky MPI Katlenburg-Lindau/Germany: Sami Solanki, Natalie Krivova NCAR, Boulder/USA Bill Randel NRL, Washington D.C./USA: Judith Lean LASP/CU, Boulder/USA: Tom Woods, Jerry Harder Univ. of Arizona, Tuscon/USA: Lon Hood To achieve a comprehensive view on solar influence on climate: 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 (MA) and its transfer down to the Earth’s surface) How do the different natural and anthropogenic forcings interact? (solar, ENSO, QBO, volcanoes, CO 2 ) Recent Activities/Coordinated Experiments 1. Coordinated model runs to investigate the tropical lower stratospheric solar signal (see poster M05B) Recently, the discrepancy between modelling studies and observations regarding the vertical structure in the tropical solar signal has been reduced (e.g., SPARC CCMVal, 2010, chapter 8). Similarly, other recent simulations with CCMs reproduce the observed vertical structure in the tropical stratosphere, but only with a (prescribed) QBO, time-varying solar cycle conditions and constant SSTs (e.g., Matthes et al., 2010), or in a CCM with fixed solar cycle conditions, with or without an internally-generated QBO (Schmidt et al., 2010). It is still unclear why a vertical structure in the solar signal appears, and whether it is related to non-linear interactions or arises from contamination by other signals (QBO, tropical SSTs). To eliminate possible aliasing between the solar cycle and the QBO, as well as between the solar cycle and the SSTs, and/or the QBO and the SSTs, the REF-B1 CCMVal experiments (Eyring et al., 2008, SPARC CCMVal 2010) were repeated with filtered SST and/or QBO data. The QBO signal (2-3 years) and solar cycle signals (larger than 10 years) have been filtered out of the SST data set used as a lower boundary for the REF-B1 simulations. Similarly, the QBO data were filtered to retain only periods between 9-48 months and exclude signals related to ENSO or the solar cycle. Currently, two CCMs with a prescribed QBO (EMAC, WACCM), and one with internally generated QBO (MRI) have finished one ensemble of the modified REF-B1 experiments (Matthes et al., 2011).SPARC CCMVal, 2010, chapter 8 2. Coordinated model runs to study the uncertainty in solar forcing (see posters M06B, M10A) Uncertainties in the solar irradiance could have a large impact on the simulation of the climate system. Recent measurements from the SIM/SORCE data set show a completely different spectral distribution than expected, with possible implications for solar heating and ozone chemistry (e.g., Haigh et al., 2010). As a first step the atmospheric response in existing (chemistry) climate model simulations using the SIM/SORCE as well as the NRL SSI data set will be compared to each other in order to test the sensitivity of different radiation and photochemistry models to different spectral irradiance data sets. In a second step coordinated sensitivity studies with a typical solar max (2002) and solar min (2008) spectrum from the NRL SSI and the SIM/SORCE data will be performed in order to investigate the differences in atmospheric response between the models in a more consistent way and study the surface climate response. This is especially important for the reliability of current SOLARIS irradiance data recommendations for CMIP5 and SPARC-CCMVal. 3. Analysis of the solar signal in CMIP5 simulations SOLARIS provided recommendations for solar irradiance data sets to be used for the CMIP5 simulations. In particular, recommendations were made for the pre-industrial control runs, as well as the future projections for models that either change total solar irradiances (TSI) only, and climate models that prescribe spectrally resolved solar irradiance variations. Since a number of long, coordinated simulations with high-top CCMs will be available within CMIP5, we are planning an intercomparison of these runs with respect to the solar signal. The tropospheric solar signal in the high-top CMIP5 simulations will be investigated in order to gain insight into the "top-down" and "bottom-up" mechanisms, e.g. the tropical Pacific response (Meehl et al., 2009) and sensitivity on model characteristics. The coordinated experiments and analysis are also described in a SPARC Newsletter Article Matthes and Kodera (2011). Future Plans News/Upcoming Meetings A special link with HEPPA (see posters M05A, M07A) has been started after the SPARC Steering Group meeting in Pune/India in February 2011. The joined SOLARIS/HEPPA initiatives will give a more complete picture of „Solar Influences on Climate“ and will enhance the intiative‘s visibility. A joined goal is a recommendation for the next IPCC round which processes (solar radiation and particles) to include in future climate studies. Joined SOLARIS/HEPPA Workshop 8-12 October 2012 Boulder/CO New and updated Website http://sparcsolaris.gfz-potsdam.de/ Acknowledgments: KM is supported within the Helmholtz-University Young Investigators Group NATHAN funded by the Helmholtz-Association through the President’s Initiative and Networking Fund, the GFZ Potsdam, and the Freie Universität Berlin. References: Gray, L.J., J. Beer, M. Geller, J.D. Haigh, M. Lockwood, K. Matthes, U. Cubasch, D. Fleitmann, G. Harrison, L. Hood, J. Luterbacher, G. A. Meehl, D. Shindell, B. van Geel, andW. White (2010), Solar Influences on Climate, Rev. Geophys., 48, RG4001, doi:10.1029/2009RG000282; Haigh, J. D., A. R. Winning, R. ToumiandJ. W. Harder (2010) An influence of solar spectral variations on radiative forcing of climate, Nature, 467, 696-699, doi:10.1038/nature09426; Manzini, E., and K. Matthes et al. (2010) Natural Variability of Stratospheric Ozone, Chapter 8 in SPARC CCMVal, SPARC CCMVal Report on the Evaluation of Chemistry-Climate Models, V. Eyring, T. G. Shepherd, D. W. Waugh (Eds.), SPARC Report No. 5, WCRP- 132, WMO/TD-No. 1526, http://www.atmosp.physics.utoronto.ca/SPARC; Matthes, K., and K. Kodera (2011), Report on 2010 SOLARIS Activities and Future Plans, SPARC Newsletter No. 36; Matthes, K. et al., 2010: Role of the QBO in modulating the influence of the 11 year solar cycle on the atmosphere using constant forcings, J. Geophys. Res., 115, D18110, doi:10.1029/2009JD013020; Matthes, K., A. Kubin, C. Blume, K. Kodera, U. Langematz, and K. Shibata (2011), SPARC-SOLARIS coordinated model runs to investigate aliasing of different factors in the tropical lower stratosphere, in preparation; Meehl, G. A., J. M. Arblaster, K. Matthes, F. Sassi and H. van Loon (2009), Amplifying the Pacific climate system response to a small 11-year solar cycle forcing, Science, 325, DOI:10.1126/science.1172872; Schmidt, H., G. P. Brasseur and M. A. Giorgetta, 2010: Solar cycle signal in a general circulation and chemistry model with internally generated quasibiennial oscillation, J. Geophys. Res., 115, doi:10.1029/2009JD012542. SOLARIS Objectives to come to a more comprehensive view on solar influence on climate: 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 (MA) and its transfer down to the Earth’s surface) How do the different natural and anthropogenic forcings interact? (solar, ENSO, QBO, volcanoes, CO2) SOLARIS HEPPA Gray et al. (2010)