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

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

Outline Introduction: Solar Cycle From Sun to Earth

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

Solar Cycle: In the Solar Wind MINMAX courtesy P. Riley

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

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

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

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

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

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

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

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

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

16 North/South asymmetry: solar cycle de Toma, 2012

17 Zucarello et al, 2012 North/South asymmetry: CMEs

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

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

20 The recent solar minimum Was it peculiar? Periodic behavior? maybe not entirely... courtesy G. de Toma 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) Love et al., 2012

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

22 Olah et al., 2012 Stellar cycles

23 Saar & Testa, 2012 Schmitt, 2012 Stellar cycles

24 Olah et al., 2012 Stellar cycles

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

26 Elsworth et al, 2012 Cycles within cycles: quasi-biennial Low frequency less sensitive to 11-year cycle: change in interior?

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

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)

29 The Sun: Is it peculiar? The jury’s out in terms of Maunder-type minima 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

30 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 Outline Grand Minima: Causes and Consequences Choudhuri, 2012; Karak & Choudhuri, 2012

31 Rozanov 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. Effect of solar Grand Minimum on climate see also Kollath et al., 2012; Souza- Echer et al. 2012; Usoskin et al., 2012

How far back can we go? How Grand can Minima get? Vaquero, 2012 Usoskin et al., 2012 Cliver,

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