J/A+A/649/A141 1000-year sunspot series (Usoskin+, 2021)
Solar cyclic activity over the last millennium reconstructed from
annual 14C data.
Usoskin, I.G., Solanki S.K., Krivova N., Hofer B., Kovaltsov G.A.,
Wacker L., Brehm N., Kromer B.
<Astron. Astrophys. 649, A141 (2021)>
=2021A&A...649A.141U 2021A&A...649A.141U (SIMBAD/NED BibCode)
ADC_Keywords: Sun
Keywords: Sun: activity - sunspots
Abstract:
The 11-year solar cycle (Schwabe cycle) is the dominant pattern of
solar magnetic activity reflecting the oscillatory dynamo mechanism in
the Sun's convection zone. Solar cycles have been directly observed
since 1700, while indirect proxy data suggest their existence over a
much longer period of time but generally without resolving individual
cycles and their continuity. Here we reconstruct individual solar
cycles for the last millennium using recently obtained 14C data and
state-of-the-art models.
Starting with the 14C production rate determined from the so far
most precise measurements of radiocarbon content in tree rings, solar
activity is reconstructed in three physics-based steps: (1) Correction
of the 14C production rate for the changing geomagnetic field; (2)
Computation of the open solar magnetic flux; and (3) Conversion into
sunspot numbers outside of grand minima. All known uncertainties,
including both measurement and model uncertainties are
straightforwardly accounted for by a Monte-Carlo method. Results:
Cyclic solar activity is reconstructed for the period 971-1900 (85
individual cycles) along with its uncertainties. This more than
doubles the number of solar cycles known from direct solar
observations. We found that lengths and strengths of well-defined
cycles outside grand minima are consistent with those obtained from
the direct sunspot observations after 1750. The validity of the
Waldmeier rule (cycles with fast rising phase tend to be stronger) is
confirmed at a highly significant level. Solar activity is found to be
in a deep grand minimum when the activity is mostly below the sunspot
formation threshold, during about 250 years. Therefore, although
considerable cyclic variability in 14C is seen even during grand
minima, individual solar cycles can hardly be reliably resolved
therein. Three potential solar particle events, ca. 994, 1052 and 1279
AD, are shown to occur around the maximum phases of solar cycles.
A new about 1000-year long solar activity reconstruction, in the form
of annual (pseudo) sunspot numbers with full assessment of all known
uncertainties, is presented based on new high-precision D14C
measurements and state-of-the-art models, more than doubling the
number of individually resolved solar cycles. This forms a solid basis
for new, more detailed studies of solar variability.
Description:
A new quantitative reconstruction of annually resolved solar activity,
in the form of SNs (at least outside grand minima) with a full
uncertainty assessment, is presented for the period 971-1900. For
the first time, individual solar cycles are presented for the whole of
the last millennium, more than doubling the existing statistics of
solar cycles.
Three tabular files are presented.
File 'osf.dat' contains annual reconstructions of the opens solar flux
(OSF) [Fo] along with its 1-sigma uncertainties [sF] and the smoothed
(22-yr SSA -- see text) values [<Fo>]. This table corresponds to
Figure 8 in the text.
File 'osn.dat' contains annual reconstructions of the sunspot number
(SN) [SN] along with its 1-sigma uncertainties [sSN] and the smoothed
(22-yr SSA -- see text) values []. This table corresponds to
Figure 11 in the text.
File 'table1.dat' presents a textual tabular version of Table 1 in the
text and contains the internal cycle number [n], years of minimum
[Ymin] and maximum [Ymax] of each cycle, cycle-averaged sunspot number
[], its 1-sigma uncertainty [sS], cycle length (min-to-min) [T],
and quality flag [q].
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
osf.dat 22 929 Data for annual opens solar flux (OSF) (fig. 8)
osn.dat 22 929 Data for annual sunspot number (SN) (fig. 11)
table1.dat 24 85 Solar activity cycles as reconstructed here
from annually resolved 14C; updated version
of the table
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See also:
VI/138 : Sunspots catalogues, 1853-1870 (Casas+, 2013)
J/A+A/390/707 : Hemispheric Sunspot Numbers 1975-2000 (Temmer+, 2002)
J/A+A/447/735 : Hemispheric Sunspot Numbers 1945-2004 (Temmer+, 2006)
J/A+A/584/A73 : Sunspot areas and tilt angles (Senthamizh Pavai+, 2015)
J/A+A/595/A104 : Scheiner drawing sunspot areas and tilt angles (Arlt+, 2016)
J/A+A/601/A106 : Sunspot on 1921-2011 (Mandal+, 2017)
J/A+A/601/A109 : Monthly numbers of sunspot groups 1749-1996 (Willamo+, 2017)
J/A+A/602/A69 : Group sunspot number series since 1739 (Chatzistergos+, 2017)
J/A+A/615/A93 : Reconstructed decadal sunspot numbers (Wu+, 2018)
J/A+A/627/A46 : Sunspot penumbra and umbral flashes models (Bose+, 2019)
J/A+A/628/A103 : Mt Wilson sunspot magnetic field measurements (Pevtsov+, 2019
J/A+A/640/A78 : Sunspot area catalogue revisited (1874-2019) (Mandal+, 2020)
Byte-by-byte Description of file: osf.dat
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Bytes Format Units Label Explanations
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1- 4 I4 yr Year [971/1899] Year
6- 10 F5.2 10+14Wb Fo Annual value of the reconstructed
opens solar flux (OSF)
12- 16 F5.2 10+14Wb e_Fo 1-sigma uncertainty of Fo
18- 22 F5.2 10+14Wb <Fo> Smoothed Fo value
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Byte-by-byte Description of file: osn.dat
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Bytes Format Units Label Explanations
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1- 4 I4 yr Year [971/1899] Year
6- 10 F5.1 --- SN Annual value of the reconstructed sunspot number
12- 16 F5.1 --- e_SN 1-sigma uncertainty of sunspot number
18- 22 F5.1 --- Smoothed sunspot number value
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I02 --- n [1/85] Internal cycle number
4- 7 I4 yr Ymin Year of solar cycle minimum
9- 12 I4 yr Ymax Year of solar cycle maximum
14- 16 I3 --- Cycle-averaged sunspot number (SN)
18- 19 I2 --- e_ 1-sigma uncertainty of
21- 22 I2 yr T Solar cycle length (min-to-min)
24 A1 -- q [012345] Quality flag (1)
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Note (1): Quality flag as follows:
0 = the cycle cannot be reliably identified (29 such cycles were found)
1 = the cycle is greatly distorted, at least one of its ends cannot be defined
(7 cycles)
2 = the cycle can be approximately identified, but either its shape or
level is distorted (14 cycles)
3 = a reasonably defined cycle (10 cycles)
4 = a well-defined cycle with a somewhat unclear amplitude (19 cycles)
5 = a clear cycle in both shape and amplitude (6 cycles)
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Acknowledgements:
Ilya Usoskin, ilya.usoskin[at]oulu.fi
History:
* 17-Sep-2021:Insert into VizieR
* 28-Jul-2022:Updated version of Table 1 sent by the author
(corrections on column "e_").
(End) Patricia Vannier [CDS] 29-Mar-2021