The recent solar minimum How unprecedent is the Sun's behavior? Andrea Opitz CESR (CNRS-UPS) University of Toulouse, France University of Bern, 17th November 2010

Solar - terrestrial relations

Solar activity cycles SOHO (NASA/ESA)

Solar activity cycles David Hathaway, NASA Marshall Space Flight Center  Few hundred years of sunspot record available  Space Age (1960's - today): just a few solar cycles, low statistics

SOHO/EIT (ESA/NASA)

Out-of-ecliptic view

SW velocity vs. latitude McComas et al. GRL 2008 Solar minimumSolar maximumNow

In-ecliptic view

Twin STEREO spacecraft Opitz, Karrer, Wurz et al Solar Physics

STEREO PLASTIC  SW bulk velocity  SW temperature  SW density Group: P. Bochsler, P. Wurz, R. Karrer, A. Opitz, L. Blush, H. Daoudi, J. Fischer, M. Sigrist et al. (UoBe) A. B. Galvin, L. Kistler et al. (UNH)

Temporal evolution of the solar wind PLASTIC proton velocity  0.5 day: ~ days: ~0.85 SWEA electron density  0.5 day: ~ days: ~0.65 Opitz et al. 2009, Solar Physics Opitz et al. 2010, Solar Physics STA  STB SWEA

Riley, Luhmann, Opitz, Linker, and Mikic 2010 JGR Temporal evolution by cross-correlation STA  STB timelag of ~6 days

Recent Sun and solar wind observations: Facts longer solar activity minimum solar magnetic field weaker coronal holes at low latitudes recurrent stream structure broader low solar wind densities total solar irradiance lower

Solar activity minimum: longer Russell, Luhmann, Jian et al. 2010

Solar polar magnetic field: weaker red: South blue: North Wilcox Solar Observatory

SW velocity vs. latitude Solar minimumSolar maximumNow McComas et al. GRL 2008

Recurrent stream structure: stronger and broader Gibson et al. 2009

Terrestrial response 1 Quiet solar minimum, though geoeffective. Interaction of the strong, broad stream structures with the terrestrial magnetosphere. Proof: sunspot number alone can not give a good prediction.

Solar irradiance  TSI lower  UV lower  visible higher Haigh 2007

Solomon et al Solar irradiance: EUV

Terrestrial response 2 Opportunity to separate the climatic effects of solar and anthropogenic sources. –Total solar irradiance lower. –Spectral solar irradiance: UV lower, visible higher. Maunder and Dalton minimums

Russell, Luhmann, Jian 2010

Solar maximum predictions weaker normal stronger

Solar eruption risks telegraph system collapsed in 1859 electric network collapsed in 1989 electric, oil and gas network satellites: GPS, communication and scientific pilots and astronauts radio communication

Summary longer solar activity minimum solar magnetic field weaker coronal holes at low latitudes recurrent stream structure broader low solar wind densities total solar irradiance lower

Questions to the audience How much does such an unprecedent solar behavior influence your work? –Climatology? –Planetology? –Cosmic rays? –Space instrumentation? –Solar and Stellar Physics? Dr. Andrea OPITZ, CESR (CNRS-UPS), University of Toulouse, France

Acknowledgements Cecile Bonneau: 'Science et vie' -> Nov/Dec 2010 Janet Luhmann: solar wind structures STEREO PLASTIC: P. Bochsler, P. Wurz, R. Karrer, A. Opitz, L. Blush et al. (UoBe) + UNH