Long term SOLAR ACTIVITY Laure Lefèvre Basic SIDC series of talks Nov. 16 th 2017 16/11/2017 Basic SIDC seminar 1
SOLAR ACTIVITY INDICES? There are many indices that represent or are linked to solar activity Radio fluxes (oldest 10.7cm, 1947) Flare index (1938 and before), Xray Flux (GOES) Geomagnetism (Ap: 1932, Kp, aa: 1868, Dst: 1957, magnetic needle 1780s) Solar Magnetic field Cosmic rays cosmogenic isotopes 16/11/2017 Basic SIDC seminar 2
SOLAR ACTIVITY INDICES? There are many indices that represent or are linked to solar activity Coronal index (FeXIV 530,3nm, 1943) SSI/TSI (TSI since 1978), EUV flux (LYRA), Mg II, CaIIK Sunspot area (RGO, 1874) Sunspot Number (1610) 16/11/2017 Basic SIDC seminar 3
SUNSPOT NUMBER 16/11/2017 Basic SIDC seminar 4
RADIO Flux at 10.7cm 16/11/2017 Basic SIDC seminar 5
AA index 16/11/2017 Basic SIDC seminar 6
Different inidces 16/11/2017 Basic SIDC seminar 7
DIRECT/INDIRECT? Direct measurements : satellite data : TSI, SSI, CME, SEPs Sunspot Number, Group Number, sunspot area Coronal index, solar eruptions, flare index Indirect measurements: Geomagnetic data Number of aurorae Cosmogenic isotope data 16/11/2017 Basic SIDC seminar 8
INDIRECT MEASUREMENT: EXAMPLE Cosmic rays (from outside of the solar system) arriving on Earth are modulated by Solar activity (open solar magnetic field) Cosmogenic isotopes are stored in natural archives ( 10 Be in ice cores, 14 C in tree rings). 16/11/2017 Basic SIDC seminar 9
INDIRECT MEASUREMENTs: EXAMPLES McCracken 2016 16/11/2017 Basic SIDC seminar 10
Cosmogenic isotope DATA 16/11/2017 Basic SIDC seminar 11
Cosmogenic isotope DATA SMF Muscheler (2016) TI 16/11/2017 Basic SIDC seminar 12
Cosmogenic isotope DATA Muscheler (2016) TI 16/11/2017 Basic SIDC seminar 13
Cosmogenic isotope DATA Muscheler (2016) TI 16/11/2017 Basic SIDC seminar 14
A DIRECT MEASUREMENT: The (SILSO) SUNSPOT NUMBER W=10xg + s 16/11/2017 Basic SIDC seminar 15
WHY SUNSPOTS? What are they? Caused by solar magnetic field Number of spots on the sun index of solar activity Cf. First two basic seminars by F. Clette 16/11/2017 Basic SIDC seminar 16
WHY SUNSPOTS? What are they? Caused by solar magnetic field Number of spots on the sun index of solar activity Cf. First two basic seminars by F. Clette 16/11/2017 Basic SIDC seminar 17
WHY SUNSPOTS? What are they? Caused by solar magnetic field Number of spots on the sun index of solar activity Cf. First two basic seminars by F. Clette 16/11/2017 Basic SIDC seminar 18
Photospheric indices: R G, R A, R Boulder, Area, Mx, F 10.7cm High linear correlations (R>95%) Chromospheric and mixed indices: TSI, CaII-K, MgII Sunspot Number vs other indices Quantitative index: Total toroidal magnetic flux emergence rate Bremmstrahlung : sunspots Gyro-resonance Plages From T. Dudok de Wit, SSN2 Workshop, Brussels 2012 05/08/2014 COSPAR MOSCOW 2014 19
Photospheric indices: R G, R A, R Boulder, Area, Mx, F 10.7cm High linear correlations (R>95%) Chromospheric and mixed indices: TSI, CaII-K, MgII Sunspot Number vs other indices Quantitative index: Total toroidal magnetic flux emergence rate Bremmstrahlung : sunspots Gyro-resonance Plages From T. Dudok de Wit, SSN2 Workshop, Brussels 2012 05/08/2014 COSPAR MOSCOW 2014 20
Hathaway (2010) : data -> 2009 16/11/2017 Basic SIDC seminar 21
TSI vs. SSN Composite TSI PMOD Many satellite missions from 1978 onwards Composite very hard to construct TSI models Facular brightening MgII index Sunspot darkening Sunspot positions and areas from RGO/SOON 16/11/2017 Basic SIDC seminar 22
TSI vs. SSN PMOD composite vs. (old) SSN Hathaway (2010) : data -> 2009 16/11/2017 Basic SIDC seminar 23
Prehistory of the Sunspot Number Sparse pre-telescopic observations: Sunspots and the 11-year solar cycle existed centuries and millenia Invention of the astronomical telescope: start of the sunspot record Galileo, Harriot, Scheiner, Fabricius 16/11/2017 Basic SIDC seminar 24
Prehistory of the Sunspot Number Sparse pre-telescopic observations: Sunspots and the 11-year solar cycle existed centuries and millenia Invention of the astronomical telescope: start of the sunspot record Galileo, Harriot, Scheiner, Fabricius 16/11/2017 Basic SIDC seminar 25
Prehistory of the Sunspot Number Sparse pre-telescopic observations: Sunspots and the 11-year solar cycle existed centuries and millenia Invention of the astronomical telescope: start of the sunspot record Galileo, Harriot, Scheiner, Fabricius 16/11/2017 Basic SIDC seminar 26
Prehistory of the Sunspot Number Sparse pre-telescopic observations: Sunspots and the 11-year solar cycle existed centuries and millenia Invention of the astronomical telescope: start of the sunspot record Galileo, Harriot, Scheiner, Fabricius 16/11/2017 Basic SIDC seminar 27
Prehistory of the Sunspot Number Sparse pre-telescopic observations: Sunspots and the 11-year solar cycle existed centuries and millenia Invention of the astronomical telescope: start of the sunspot record Galileo, Harriot, Scheiner, Fabricius 16/11/2017 Basic SIDC seminar 28
A brief history of the Sunspot Number: R.Wolf R. Wolf: introduction of the Wolf number [1849-1893]: W= 10 Ng + Ns Standard Fraunhofer refractor (Zürich Observatory) D= 83mm, F= 1320mm Mag= 64x R. Wolf in 1855 (1849-1893) 16/11/2017 Basic SIDC seminar 29
A brief history of the Sunspot Number: R.Wolf Reconstruction of the sunspot number from historical data: 1749 1849 Scale based on successive primary observers Zürich primary observers: Staudach 1749-1787 Flaugergues 1788-1825 Schwabe 1826-1847 Wolf 1848-1893 Wolfer 1893-1928 Brunner 1929-1944 Waldmeier 1945-1980 K.H.Schwabe Discoverer of the 11-year solar cycle 16/11/2017 Basic SIDC seminar 30
A brief history of the Sunspot Number: Zürich Zürich period: Continuation of Wolf s method 3 directors Prime reference = Zürich Network of collaborating stations: Scaled to Zürich: k personal coefficients Only used to fill missing days Alfred Wolfer (1877-1925) William Brunner (1925-1944) M. Waldmeier [1944-1980] 16/11/2017 Basic SIDC seminar 31
A brief history of the Sunspot Number: Zürich Second base station [1957]: Specola Solare Locarno (Ticino, SW) Observer: S. Cortesi Still observing today: continuty with Zürich! 16/11/2017 Basic SIDC seminar 32 S. Cortesi and M. Waldmeier circa 1955
The GROUP NUMBER Created by Hoyt and Schatten in 1996 (H&S 1998) Dived into a lot of archives. Not the same sensitivity to higher regime than SN although group separation might be tricky around maxima 16/11/2017 Basic SIDC seminar 33
The GROUP NUMBER Revision of early GN and the Maunder Minimum (1610-1749) 16/11/2017 Basic SIDC seminar 34
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Overview of the Group Number corrections Revision of early GN and the Maunder Minimum (1610-1749) Backbone reconstruction (1749-2015) Svalgaard & Schatten 2016 Greenwich trend (1885-1915) 14/07/2017 VARSITI IRKUTSK July 10-15 2017 36
Overview of the Sunspot Number corrections Schwabe - Wolf transition (1849-1864) Waldmeier s spot weighting (1947-1980) Locarno s variable drifts (1981-2015) 14/07/2017 VARSITI IRKUTSK July 10-15 2017 37
A closer (brief) look at these transitions for SN From the most recent to the oldest Wolfer scale 0.6 disappeared The Zurich-Brussels (Locarno) transition The Waldmeier transition The Wolf-Wolfer transition The Schwabe-Wolf transition The Staudacher-Schwabe transition 14/07/2017 VARSITI IRKUTSK July 10-15 2017 38
The Zurich-Locarno transition (1980) Issue corrected but recomputation possible : correction applied in SNV2.0 14/07/2017 VARSITI IRKUTSK July 10-15 2017 39
Specola s variable drift (1981-2015) 14/07/2017 VARSITI IRKUTSK July 10-15 2017 40
The Waldmeier transition (1947) Issue mostly settled : applied to SNV2.0 14/07/2017 VARSITI IRKUTSK July 10-15 2017 41
Using multiple solar indices Lockwood et al. (2014) 14/07/2017 VARSITI IRKUTSK July 10-15 2017 42
Weighting factor: direct determination Simultaneous weighted/unweighted counts (Specola station, Locarno): 215 direct double counts (M. Cagnotti, Locarno, 2014-2015) 3661 Locarno drawings recounted (1997-2014, L. Svalgaard) 14/07/2017 VARSITI IRKUTSK July 10-15 2017 43
Weighting factor: direct determination Simultaneous weighted/unweighted counts (Specola station, Locarno): 215 direct double counts (M. Cagnotti, Locarno, 2014-2015) 3661 Locarno drawings recounted (1997-2014, L. Svalgaard) Mean ratio: ~ 1.16 +/- 0.035 Inflation factor depends on the level of activity! 14/07/2017 VARSITI IRKUTSK July 10-15 2017 44
Synthesis of published values Comparisons with external indices Lockwood et al. 2014 Rg Without SOON Rg Ag Svalgaard 2013 Clette & Lefèvre 2016 Rg & Ag (2σ) Lockwood et al. 2016 fof2 Lockwood et al. 2016 Rg Lockwood et al. 2016 multi S2013: 1.20 L2014: 1.116 ± 0.03 CL2016: 1.164 ± 0.02 L2016-1 FoF2: 1.12 ± 0.03 L2016-1 AG: 1.136 L2016-4 NG, CaII, SN MWO: 1.128 ± 0.034 CL2016: 1.16 ± 0.035 1.05 > 1.177 ± 0. S2016: 1.05 > 1.20 Direct counts Clette & Lefèvre 2016 daily SN Clette & Lefèvre 2016 mean cycle 23-24 Svalgaard 2017 monthly SN 1.10 1.12 1.14 1.16 1.18 1.20 14/07/2017 VARSITI IRKUTSK July 10-15 2017 45
Main RESULTS of reconstructions Long term trends gone 16/11/2017 Basic SIDC seminar 46
Cosmogenic isotope DATA SMF Muscheler (2016) TI 16/11/2017 Basic SIDC seminar 47
PRESENT: The SILSO network 92 stations in 50 countries Still highly concentrated around Europe Low participation in N-America (AAVSO) 16/11/2017 Basic SIDC seminar 48
PRESENT: The SILSO network 92 stations in 50 countries Still highly concentrated around Europe Low participation in N-America (AAVSO) Professionnals 34% N-America S-America 5% 9% Africa 3% Amateurs 66% Asia 12% E-Europe 14% W-Europe 57% 16/11/2017 Basic SIDC seminar 49
FUTURE SILSO is now undergoing a lot of improvements Versioning system of SN Quality control of the whole network data being researched and implemented 16/11/2017 Basic SIDC seminar 50
The well-known 11 YEARS cycle The 11-year cycle is not exactly 11 years! Varies between 9 and 14 years Long term variability in the length of the Solar Cycle 16/11/2017 Basic SIDC seminar 51
Variability of cycle length 16/11/2017 Basic SIDC seminar 52
Shape of a solar cycle Asymmetry in rise and decline (Waldmeier effect) Double peaks Minima maxima Minima are not real separations between cycles, overlap between cycles (cf. Butterfly diagram) North / South asymmetry 16/11/2017 Basic SIDC seminar 53
Waldmeier effect Asymmetry between rise time and decline time: strongest for high-amplitude cycles 16/11/2017 Basic SIDC seminar 54
Double peaks Gnevishev gap (Gnevishev, 1963) There is no consensus on the origin signature of a quasi-biannual oscillation effect of the N-S phase shift in activity? Norton & Gallagher (Solar Phys. 261, 193, 2010) show that each hemisphere has its doublepeaked activity. 16/11/2017 Basic SIDC seminar 55
North South asymmetry N-S asymmetry / phase shift N-S coupling The two hemispheres never get out of phase by more than ~2 years (1.8 yrs, 10 mts). 16/11/2017 Basic SIDC seminar 56
SHAPE of a cycle 16/11/2017 Basic SIDC seminar 57
Longer term periodicities Gleissberg Cycle 87 years Suess Cycle (de Vries Cycle) 208 years Hallstatt cycle 2300 years 16/11/2017 Basic SIDC seminar 58
the Gnevyshev Ohl Effect a two-cycle variation with odd numbered cycles higher than the preceding even numbered cycles 16/11/2017 Basic SIDC seminar 59
the Gnevyshev Ohl Effect 16/11/2017 Basic SIDC seminar 60
Grand Minima MAXIMA? 16/11/2017 Basic SIDC seminar 61
Maunder minimum Recent studies show a few cycles 16/11/2017 Basic SIDC seminar 62
What is this series used for? Climate models Prediction of solar activity for everything/everyone in space (ESA,CNES ) Space weather (short term) 16/11/2017 Basic SIDC seminar 63
TSI vs. SSN : climate impact How does the (new) SSN influence models? 16/11/2017 Basic SIDC seminar 64
Can we use THESE DATA to predict the next cycles? McNish & Lincoln 16/11/2017 Basic SIDC seminar 65
Can we use THESE DATA to predict the next cycles? McNish & Lincoln Geomagnetic precursors (aa) Dynamo theory 16/11/2017 Basic SIDC seminar 66
PredictiONS FOR Cycle 24 From Pesnell, 2008 Climatology and Recent Climatology Spectral and Neural Network Precursor Physics Based From 3 rd Solar Panel predictions 2008
REFERENCES Topical Issue Solar Physics: Clette et al. (2016) https://doi.org/10.1007/s11207-016-1017-8 Clette & Lefèvre (2016) https://doi.org/10.1007/s11207-016-1014-y Hathaway (2010) https://doi.org/10.1007/lrsp-2015-4 Kopp (2016) https://doi.org/10.1007/s11207-016-0853-x Muscheler (2016) https://doi.org/10.1007/s11207-016-0969-z Usoskin (2008) https://doi.org/10.12942/lrsp-2008-3 Vaquero (2017), Proceedings of the XII Scientific Meeting of the Spanish Astronomical Society http://www.sidc.be/silso https://solarscience.msfc.nasa.gov 16/11/2017 Basic SIDC seminar 68
THANK YOU 16/11/2017 Basic SIDC seminar 69
ADDITIONAL MATERIAL 16/11/2017 Basic SIDC seminar 70
INDIRECT MEASUREMENTs: EXAMPLES McCracken 2016 Signal modulated by many different parameters (has to be calibrated with SN for 400 yrs). 16/11/2017 Basic SIDC seminar 71
History of the Sunspot number construction Zurich primary observers Historical stations: daisy-chaining 1826: Start Scwhabe 1849: Start Wolf 1861: First auxiliary observers 1865: First assistants in Zurich 1867: End Schwabe 1877: Start Wolfer 1893 End Wolf 1947: Start sunspot weighting 1981: Zurich to Locarno, SILSO network Schwabe k= 1.25 1826 1849 Wolf k = 1 1861 1864 1867 1877 Wolfer - Cortesi k = 1 Zurich assistants k = 1 Auxiliary stations yearly/monthly k scaling 1893 1947 1981 16/11/2017 Basic SIDC seminar 72 SILSO network
Sunspot Number vs other indices Very high correlation with photospheric parameters (R 2 >0.95): R G, R A, R Boulder, Area, Mx (Bachmann et al. 2004, Rybansky et al. 2005, Wilson and Hathaway 2006, Tapping et al. 2007, Bertello et al. 2010, Hempelmann and Weber 2012) Measure of the global emergence rate of (toroidal) magnetic flux (Petrovay 2010, Stenflo 2012) Mean mag. flux Sunspot Nb. Stenflo, 2012 Chromospheric and mixed indices (TSI, CaII-K, MgII): Good but lower correlations: Non-linear relation Time lags (magn. flux dispersion) Solanki & Fligge 1999 21/11/2014 ESWW11 Nov. 2014 73
TSI vs. SSN How does the (new) SSN influence models? 16/11/2017 Basic SIDC seminar 74
Numbering of cycles Following Wolf's numbering scheme, the 1755 1766 cycle is traditionally numbered "1". Wolf created a standard sunspot number index, the Wolf index, which continues to be used today. 16/11/2017 Basic SIDC seminar 75
16/11/2017 Basic SIDC seminar 76 Vaquero (2017)
The Wolf-Wolfer transition (1877-1893) Still at the analysis stage 14/07/2017 VARSITI IRKUTSK July 10-15 2017 77
The Wolf-Wolfer transition (1877-1893) Unique interval in the SN series: SN number is the average between two observers (Wolf+Wolfer) Critical double transition: From Wolf 40mm portable refractor to Wolfer with 82mm refractor New counting rules: small spots, multiple umbrae Daisy-chaining k coefficient 0.6 between Wolf series (1700-1893) and modern series (1883-now) Trend over 1876-1883: Wolfer gaining experience (counting progressively more spots) Mix with other assistants (mutual influence?) 1883-1893 gives a correction factor of about 0.55 (< 0.6) Should the Wolf series before 1876 be raised by 10%? Wolfer 1895 14/07/2017 VARSITI IRKUTSK July 10-15 2017 78
The Schwabe-Wolf transition (1826-1867) Applied in SNV2.0 14/07/2017 VARSITI IRKUTSK July 10-15 2017 79
The Schwabe-Wolf transition (1849-1864) Comparison with the original Group Number (Hoyt & Schatten 1998): 14% upward jump in 1864 Drift after 1880 (cf. RGO trend in Hoyt& Schatten GN) Schwabe scale lower before 1840 Early values 10% too low versus scale after 1864. Comparison with the Group Number over a wider time interval (Backbone GN, Svalgaard & Schatten 2016) 14% upward jump in 1864 Schwabe scale lower before 1840 Early values at same level as after 1864. No robust indication that the pre- 1826 scale is grossly wrong relative to post-1865 numbers 14/07/2017 VARSITI IRKUTSK July 10-15 2017 80
The Staudacher Schwabe transition (1800-1826) Work in progress 14/07/2017 VARSITI IRKUTSK July 10-15 2017 81
Early data and the Staudacher- Schwabe transition Illarionov & Arlt, SC6, Levi 14/07/2017 VARSITI IRKUTSK July 10-15 2017 82