Space Climate and the Recent Unusual Solar Minimum

1. Space Climate and the Recent Unusual Solar Minimum Sarah Gibson drawing upon results of IAU Symposium 286 Proceedings (and other recent publications)

2. Outline • Introduction: Solar Cycle From Sun to Earth • The Recent Solar Minimum: Was it Peculiar? • The Sun: Is it Peculiar (among Stars)? • Grand Minima: Causes and Consequences

3. Outline • Introduction: Solar Cycle From Sun to Earth

4. The 11-year Sunspot cycle The Solar Butterfly Diagram Solar Cycle: At the Sun

5. Solar Cycle: At the Sun

6. Solar Cycle: In the Solar Wind courtesy P. Riley MIN MAX

7. Solar Cycle: At the Earth Thermospheric density Solomon et al. 2010

8. Outline Priest, 2012 • The Recent Solar Minimum: Was it Peculiar? • Sunspots Long, slow-to-arrive minimum, with very few sunspots

9. SSN revised Svalgaard, 2012 • Group Sunspot Number vs. Wolf (Zurich) Sunspot Number: • WSN needs weighting based on sunspot size (20% increase < 1940s) 9

10. SSN revised Svalgaard, 2012 • Group Sunspot Number vs. Wolf (Zurich) Sunspot Number: • GSN needs increase by 50% < 1885 No Modern Maximum! 10

11. Maybe not: Long and quiet minima have occurred (on century time scale e.g. Gleisberg cycle) The recent solar minimum Was it peculiar? 11 Courtesy L. Svalgaard

12. Outline • The Recent Solar Minimum: Was it Peculiar? • Magnetic morphology • weak polar magnetic field de Toma, 2012

13. Not as dipolar as prior space age minima... Gibson and Zhao, 2012 The Porcupine Sun! 13 Courtesy Predictive Science Inc.

14. 1996 Solar wind velocity from STEL interplanetary scintillation data Tokumaru et al., 2011 2008 Fast wind threads the ecliptic, long and strong high-speed solar wind streams in 2008 Vmax 23/24 Vmax 22/23 1996 2007 2008 2009 14 17 Vlength 23/24 Vlength 22/23 de Toma, 2012 Maris et al., 2012

15. Weak dipole (porcupine): again, probably not on century time-scales The recent solar minimum Was it peculiar? de Toma, 2012 15 see also: Luhmann et al., 2012; Tlatov et al., 2012

16. Outline • The Recent Solar Minimum: Was it Peculiar? • Morphology • weak polar field --> porcupine sun • Longitudinal variation--> periodicities 1996 Periodicities (9, 13, 27 day) of wind in aurora and radiation belt The Earth was ringing for most of 2008 Vsw auroral power rad. belt 2008 Gibson et al., 2009

17. 2008-2009 see also: Echer et al., 2012; de Toma, 2012 • Strong periodicity: Combination of • warped heliospheric magnetic structure • long-lived, low-latitude coronal holes • low activity 2006 Love et al., 2012 Courtesy Neal Sheeley 19 21

18. The recent solar minimum Was it peculiar? Love et al., 2012 Periodic behavior? maybe not entirely... But then again, the recent minimum had unusually strong and sustained periodic behavior compared to prior minima in the geomagnetic record - extended declining phase (see also Luhmann, 2012) courtesy G. de Toma 20

19. Outline • The Sun: Is it Peculiar (among Stars)? Judge and Thompson 2012 21 Giampapa, 2012; Schmitt, 2012; Olah et al., 2012; Saar and Testa, 2012; Valio, 2012

20. The Sun: Is it peculiar? Not in terms of cycling 25 Judge and Thompson, 2012

21. The Sun: Is it peculiar? Maybe? or do we just need to fill in the middle? Judge and Thompson, 2012 Need to better understand mechanism(s) underlying solar dynamo Brandenburg & Guerrero, 2012; Candalaresi & Brandenburg, 2012; del Sordo et al., 2012; Elsworth et al., 2012; Guerrero et al., 2012; Warnecke et al., 2012

22. The Maunder Minimum • What do we know observationally about the Maunder minimum? • sudden onset, gradual recovery (Usoskin et al., 2000) • Ice core/tree ring cosmic-ray data indicate magnetic cycles continue even without sunspots (Beer et al., 1998; Miyahara et al., 2004)

23. The jury’s out in terms of Maunder-type minima The Sun: Is it peculiar? Judge and Thompson, 2012 Warning: models indicate cycling stars could masquerade as non-cyclic or Maunder-type minima stars, if surface flux distribution (polar-to-equator) oscillates out-of phase Isik, 2012 29

24. Outline • Grand Minima: Causes and Consequences • What do we know from models? Nandy, 2012 • Stochastic fluctuations, e.g., in the meridional flow and the dynamo α-effect (Charbonneau & Dikpati 2000) • Non-linear feedback of the fields on the flows (Tobias 1997) that may lead to chaotic modulation • Sudden changes in dynamo ingredient: induce Maunder-type minimum by decreasing poloidal field (alternatively, by decreasing meriodonal flow--i.e. Karak (2010)) • Cyclic behavior continued in the radial (solar wind) magnetic field) • Sunspot flux emergence recovers by (non-Babcock-Leighton) alpha-effect Choudhuri, 2012; Karak & Choudhuri, 2012 30

25. Effect of solar Grand Minimum on climate Rozanov et al., 2012 see also Kollath et al., 2012; Souza-Echer et al. 2012; Usoskin et al., 2012 • Dalton-like minimum conditions • Solar irradiance • Spectral solar irradiance • Energetic electron preciptation • Solar protons and galactic cosmic rays • Solar activity decrease can modulate anthropogenic effects: • Ozone recovery delay • Greenhouse warming compensated partially • Stratospheric cooling (anthropogenic) enhanced by solar forcing • varies by atmospheric layer and geographical region • Solar irradiance variability most significant. 31

26. How far back can we go? How Grand can Minima get? 1000 -8000 Vaquero, 2012 -7000 Usoskin et al., 2012 Cliver, 2012

27. Conclusions • Was the recent solar minimum unusual? • For the space age, yes (long, low SSN, non-dipolar Sun) • For the sunspot record, no (last century, e.g.) • For the eclipse record, maybe not (non-dipolar porcupine structure seen) • For the geomagnetic record, perhaps (periodic behavior very strong) • Is the Sun unusual? • Not in terms of cycling • Dynamo nature? • Maunder-type minima? • Long-term solar/stellar variability implications • Climate • Space climate • Other planets Bertucci, 2012 • Biology - on Earth OsarioRosales & Mendoza, 2012 • and other planets! Abreveya, 2012