Rank | Name | Type | Technique | T_{begin} | E.M. | T_{max} | E.M. | R_{max} | E.M. | T_{Pred} | Ref. | Remarks |
---|---|---|---|---|---|---|---|---|---|---|---|---|

1 | Schatten | physical | SODA-index | Nov 07 | 12 | Jan 13 | 12 | 80 | 35 | Nov 05 | (1);(2); (3) | (3): Update by Pesnell and Schatten; May 07 |

2 | Sello | stat+phys | Nonlinear dynamics applied on SODA-index | - | - | Apr 11 | - | 96 | 25 | Jul 03 | (1) | - |

3 | Svalgaard | physical | Polar magnetic field | - | - | Jun 11 | 12 | 70 | 2 | Jan 05 | (1);(2); (3) | - |

4 | Choudhuri | physical | Polar field & randomness integrated in dynamo model | Jan 09 | 12 | Jun 12 | 12 | 75,0 | 2,7 | Mar 07 | (1); (2); (3) | - |

5 | Lundstedt | stat+phys | Lund Solar Activity Model (Neural network+Physics) | - | - | - | - | 85 | 25 | Jun 05 | ;(2);(3);(4);(5)(1) | Own extrapolation |

6 | Dikpati | physical | Meridional flow & magnetic memory | Dec 07 | 3 | 2012 | - | 169 | 12 | Mar 06 | (1);(2);(3); (4) | Update Aug 07 confirms initial results of Mar 06 |

7 | Hathaway | stat+phys | Meridional flow (sunspots) & Trise-Amplitude relation | Dec 06 | 3 | 2010 | - | 145 | 25 | Mar 06 | (1);(2);(3);(4) | - |

8 | Maris | physical | Flare energy release during descending SC-phase | - | - | - | - | Low | - | 2003 | (1);(2) | Max. est. 70 |

9 | Badalyan | physical | Coronal Green line (10 years in advance of R) | Jan 07 | 12 | Jan 11 | 12 | 50 | - | Dec 00 | (1) | - |

10 | Duhau | stat+phys | Non-linear model on Rmax en aa-min | - | - | - | - | 87,5 | 23,5 | Mar 03 | (1) | - |

44 | De Jager, Duhau | stat+phys | Non-linear dynamo model and longterm oscillations in R_{max} and aa_{min} | Jun 08 | 8 | Jan 2014 | 6 | 68 | 17 | Dec 08 | (1); (2) | - |

11 | Clilverd | physical | Variation of the atmospheric cosmogenic radiocarbon | - | - | - | - | Low | - | 2004 | (1);(2) | Max. est. 70; Symposium |

12 | Kane | stat+phys | Precursor method based on aa-index at SC-minimum | - | - | - | - | 124 | 26 | Jul 07 | (1) | Upper limit= 142 +/- 24 if no correction for 3nT |

13 | Rabin | stat+phys | Geomagnetic precursor method based on aa- and Ap-index | - | - | - | - | 115 | 30 | May 07 | (1) | Symposium |

14 | Hathaway | stat+phys | Geomagnetic precursor method based on aa-index | - | - | Jan 11 | 12 | 160 | 25 | Dec 06 | (1);(2)(3);(4);(5) | - |

15 | Dabas et al. | stat+phys | Geomagnetic precursor method based on Ap-index (SC17-23 only) | - | - | Dec 11 | 4 | 124 | 23 | May 08 | (1);(2) | Max. SC24 45+/-4 months after SC Min. |

16 | Jiang, Chatterjee, Choudhuri | physical | Poloidal field and high diffusivity in convection zone | - | - | Sep 13 | 18 | 85 | 10 | Feb 08 | (1);(2) | Own extrapolation from Fig. 16 |

17 | Hill | physical | Helioseismological observations | - | - | - | - | Weak | - | Jun 08 | (1) | Est. 80+20 |

18 | Wang et al. | statistics | Statistics based on previous, cherry-picked solar cycles | Oct 07 | 5 | Jun 11 | 5 | 119,5 | 12,4 | Nov 08 | (1) | SC Tmax 44+5 months after Tmin |

19 | Pishkalo | statistics | Statistics on sunspotnumber parameters | - | - | May 12 | 1 | 110,2 | 33,4 | Nov 07 | (1) | - |

20 | Kilcik et al. | statistics | Nonlinear methods (Hurst exponent and Sugihara-May algorithl) | - | - | Dec 12 | - | 87,4 | - | Dec 08 | (1) | Preprint Arxiv |

21 | Kane | statistics | Precursor SGN in 10°-30°N | - | - | - | - | 130 | 16 | Nov 07 | (1); (2) | - |

22 | Kane | statistics | Gnevyshev-Ohl-Kopecky rule and Three-Cycle-Rule (TRC) | - | - | - | - | 132 | 36 | Oct 08 | (1) | Large error! GOK predicts 106+42. |

23 | Kane | statistics | Cherry-picking of SC's total duration and Rmax | - | - | - | - | 94 | 44 | Feb 08 | (1) | Large error! |

24 | Tong Xu | statistics | Empirical Mode Decomposition and AR-model on sunspotnumbers | - | - | Dec 11 | 12 | 112 | 8 | Jun 08 | (1);(2) | Method predicts SC23-min in 2007 |

25 | Gholipour | statistics | Spectral analysis and neurofuzzy modelling | - | - | Jan 12 | 12 | 145 | - | Mar 05 | (1) | - |

26 | Kane | statistics | Spectral analysis Sunspots (Maximum Entropy Method and MR-analysis | - | - | Dec 12 | 24 | 92 | 11 | Oct 99; Nov 07 | (1); (2) | Update down from 105+9 |

27 | Echer | statistics | Spectral analysis | Dec 07 | 12 | Dec 12 | 12 | 116 | 13,2 | Jun 04 | (1) | - |

28 | Wang | statistics | Low and high rising velocity groups | - | - | Mar 12 | 12 | 101,3 | 18,1 | Jul 02 | (1) | - |

29 | Kaftan | statistics | Kinematical modeling of solar parameters | Aug 07 | 16 | Jun 12 | 14 | 163 | 37 | 2005 | (1);(2) | Updated |

30 | Euler | statistics | MSAFE (advanced McNish-Lincoln) | Jun 07 | - | Mar 11 | - | 110,5 | - | Aug 04 | (1) | 50% percentile; NASA Report |

31 | Myung-Hee | statistics | Statistics + Odd-even cycles | Dec 06 | 14 | Nov 10 | 6 | 122 | 6 | Sep 04 | (1) | Annual R_{max}; NASA Report |

32 | Hathaway | statistics | Statistics on daily, monthly, yearly R | < 07 | - | - | - | Large | - | Nov 03 | (1) | Max. est. 160; NASA Report |

33 | Ahnert | statistics | Statistics + Trise-Amplitude relation | Jun 07 | 12 | Nov 11 | 12 | 92,3 | 29,9 | - | (1) | Own extrapolation from book |

34 | Chopra | statistics | Precursor of Ap & R | - | - | - | - | 139,3 | - | 2005 | (1);(2);(3) | T_{max} = T_{min} + 52 ; Symposium |

35 | Lantos | statistics | Skewness solar cycle & odd-even cycles | - | - | 2011 | - | 108 | 38 | Mar 06 | (1);(2) | T est. = Jun 11 |

36 | Kontor | statistics | Fourrier spectrum of Gleisberg and Schwabe cycles | Jan 08 | +7/-4 | Dec 12 | 11? | 87 | 12? | Dec 08 | (1) | Incl. SC25 (low) ; Website; Update from Mar O6, with Rmax = 70 |

37 | Clilverd | statistics | Medium- and longterm periodicities in C^{14} applied on Wolfnumber | - | - | - | - | 42 | 34 | Sep 06 | (1);(2) | Incl. SC25 (low) |

38 | Du | statistics | Inter-cycle analysis of extremums and ascending/descending phases | Mar 07 | 7 | - | - | 149,5 | 27,6 | May 06 | (1);(2) | Incl. SC25 (High) |

39 | Baranovski | statistics | Non-linear dynamics and chaos theory | - | - | Jan 12 | 12 | 80 | 21 | 2006 | (1) | Symposium |

40 | Javaraiah | statistics | Hemispheric Sunspot Area, North-South asymmetry, 44-year periodicity | - | - | - | - | 87 | 7 | Jan 07, Oct 08 | (1); (2);(3) | Update up from 74+10 |

41 | IPS (not published) | statistics | Average of last 8 solar cycles | Oct 07 | 6 | Aug 11 | 12 | 134 | 50 | Apr 07 | (1) | Website |

42 | Hiremath | statistics | Forced and damped harmonic oscillator (sinusoidal and transient parts) + AR-model | Jul 08 | 2 | - | - | 110 | 11 | 2006a; 2007; Jan 2008 | (1);(2);(3) | Incl. SC25-38; Update in 2008 |

43 | Tlatov | statistics | Based on duration of preceding cycle | - | - | Mar 11 | 8 | 110 | 27 | Dec 07 | (1) | - |

45 | Uwamahoro | statistics | Neural networks based on R and aa-index | Jan 08 | - | Jun 12 | 10 | 117,5 | 8,5 | Dec 08 | (1) | Tsub>min assumed |

The method by Li et al. (2005) and NASA/Technical Report on the use of the modified precursor method by Wilson and Hathaway (July 2008) were not inserted into the table because of the various predictions that were being made for SC24. Wilson and Hathaway were added as supplemental reference for Method 15 (Dabas).

Watari (December 2008) and Volobuev and Makarenko (April 2008) were not added to the table because of no clear predictions. Both do predict SC24-maximum will be lower than that of SC23.

Cameron and Schlüssler (October 2008, ArXiv) provide comments on the timings of minimum and maximum of a solar cycle and the implications on precursor methods. Vaquero and Trigo (June 2008) also caution on SC-amplitude prediction based on length of previous SC.

**Pesnell W.D. (August 2008) provides an overview of comments on more than 50 prediction methods of the SC24-amplitude.**

**Obridko and Shelting (March 2008) also provide an overview and discussion of various prediction methods.** Their paper uses also three different methods resulting in three different results for SC24-maximum, although in the medium category (80-120). Not included in table.

Of the 17 methods that have made a prediction of the timing of solar cycle minimum, only 7 have this timing still in their error margin (methods 1, 4, 27, 29, 36, 42 and 44).

Type | T_{begin} | E.M. | T_{max} | E.M. | R_{max} | E.M. |
---|---|---|---|---|---|---|

Physical | Jan 08 | 10 | May 12 | 14 | 83,2 | 13,6 |

Mixed | (Dec 06) | (3) | Mar 11 | 8 | 117,1 | 25,3 |

Statistical | Sep 07 | 10 | Jan 12 | 11 | 112,2 | 24,0 |

Panel SC 24 LOW | Mar 08 | 6 | Aug 12 | - | 90 | 10 |

Panel SC 24 HIGH | Mar 08 | 6 | Oct 11 | - | 140 | 20 |

Above tables and chart reflect predictions for the upcoming solar cycle. Averaging all results, solar cycle 24 is expected to start late 2007 (__+__ 11 months) and reach a maximum monthly Wolfnumber of **107,0 +/- 22,5** early 2012 (__+__ 12 months).

There is however a strong divergence between the statistical and more physically oriented approaches. The first methods result mostly in an average to strong cycle, whereas the latter -upon 2 noteable exceptions- indicate a low to moderate cycle (taking the error margins (E.M.) into account). Moreover, Schatten, having predicted correctly the amplitude of the 2 previous solar cycles, now indicates only a low to moderate cycle. But Dikpati and Hathaway, having worked on the sun's internal plasma flows, come up with a large amplitude. Unfortunately, this method is new and still has to prove itself. During the prediction of the previous solar cycle, geomagnetic precursor methods (Thompson,...) were much hyped too, yet they failed significantly.

There is also the Gleissberg cycle, which shows up in Lundstedts method as well as in other statistical spectral and wavelet analysis. SC23 *may* be regarded in this context as solar activity in its early decline for decades to come.

One final note concerns low cycle amplitudes. Though Wolfnumbers may be low, this does not mean that overall solar activity will be low. Just as in SC23, despite low to moderate Wolfnumbers, occasionally big complex groups will be present and produce strong solar flares, even till long after sunspot cycle maximum. Thus SC24 evolution may be similar to SC23, but at an even lower activity level.

Physical/Statistical method 44 (De Jager/Duhau) and statistical method 45 (Uwamahoro et al.) were added. Statistical method 36 (Kontor) was updated. Of the 45 methods, 34 refer to a scientific paper, while 1 (method 20) is in pre-print. 4 predictions were made at a symposium (numbers 11, 13, 34 and 39), 3 in a NASA-report (numbers 30, 31 and 32), 2 come from a website (36 and 41), and 1 was taken from a formula in a book (33). Summary-chart was updated.

*25 January 2009* - 10 new methods were added: Physical/Statistical method 15 (Dabas), physical methods 16 (Jiang) and 17 (Hill), and statistical methods 18 (Wang), 19 (Pishkalo), 20 (Kilcik), 21-23 (all by Kane), and 24 (Tong Xu). Updates were made to methods 6 (Dikpati), 26 (Kane), 40 (Javaraiah) and 42 (Hiremath). Of the 43 methods, 32 refer to a scientific paper, while 1 (method 20) is in pre-print. 4 predictions were made at a symposium (numbers 11, 13, 34 and 39), 3 in a NASA-report (numbers 30, 31 and 32), 2 come from a website (36 and 41), and 1 was taken from a formula in a book (33). Summary-chart, -table and -comments were updated. A section "Comments on prediction methods" was added right underneath the table.

*08 September 2007* - Methods 2 (Sello), 12 (Kane), 13 (Rabin) and 43 (Tlatov) were added. Methods 1 (Schatten) and 4 (Choudhuri) were updated. Of the 33 methods, 21 refer to a scientific paper, while 2 (methods 42 and 43) are in pre-print. 4 predictions were made at a symposium (numbers 11, 13, 34 and 39), 3 in a NASA-report (numbers 30, 31 and 32), 2 come from a website (36 and 41), and 1 was taken from a formula in a book (33). Summary-chart, -table and -comments were updated.

*28 April 2007* - Results of the 2nd meeting of the NOAA-panel: Press release and technical discussion and overview of the different prediction methods. SC23-minimum is predicted for March 2008 +/- 6 months. As solar activity further evolves, it will become clear whether SC24 is heading for a 140 +/-20 maximum in October 2011, or for 90 +/-10 in August 2012. Website with the proceedings and results of the panel can be found here.

*13 April 2007* - Statistical method 42 (Hiremath) was added. This paper is in *preprint*. Summary chart was updated.

*05 April 2007* - After a question by Dr. R. P. Kane, I've updated the entire reference-column. Links in bold (e.g. **(1)**) now refer to the true scientific paper. Of the 28 methods, 19 refer to a publication in a scientific paper. Choudhuri is still in the acceptance phase, while it is unclear which of the papers published by Lundstedt contains the actual prediction (85+/-25 is my own extrapolation from the average of solar cycles 12-15, corresponding to the result from the wavelet studies -WCMax and Timescale are about the same for 1900 as for 2000).

The other 9 methods can be summarized as follows: 3 are the result of a NASA-report, 3 come from presentations on a Symposium, 2 come from a website and 1 comes from a formula in a book. One method was removed, as it was actually a double (Gholipour Ali). Appropriate remarks were made in the last column. Summary-chart, -table and -comments were updated.

*02 April 2007* - Statistical method 41 (IPS) was added. This method is apparently based on simply averaging the last 8 solar cycles. As this series contains the 4 most active cycles since 1750, the method virtually excludes the prediction of a possibly weak SC24. Notice also the very large uncertainty. IPS will adjust this average cycle as the new cycle unfolds. Summary-chart, -table and -comments were updated.

*25 February 2007* - Statistical method 40 (Javaraiah) was added. Summary chart was updated.

*21 January 2007* - Prediction 4 (Choudhuri et al.) was added. Rmax & Tmax are my own extrapolations.

*01 January 2007* - Comments on Hathaway & Wilson (Prediction 14) were added (References, link (3)).

*22 December 2006* - Prediction 11 (Hathaway) was added. Please note that maximum aa-i occurs in October 2003, at the time of the Halloween-groups. Summary-chart was updated.

*11 November 2006* - Statistical methods 15 (Gholipour et al.) and 39 (Baranovski et al.) were added. Summary-chart was updated.

*02 November 2006* - Predictions 37 (Clilverd et al.) and 38 (Z. L. Du et al.) were added. Prediction 29 (V. Kaftan) was updated. Charts and numbers were adapted accordingly.

Original: 07 May 06