J/A+A/640/A78 Sunspot area catalogue revisited (1874-2019) (Mandal+, 2020)
Sunspot area catalogue revisited: Daily cross-calibrated areas since 1874.
Mandal S., Krivova N., Solanki S.K., Sinha N., Banerjee D.
<Astron. Astrophys. 640, A78 (2020)>
=2020A&A...640A..78M 2020A&A...640A..78M (SIMBAD/NED BibCode)
ADC_Keywords: Sun
Keywords: Sun: activity - sunspots - Sun: magnetic fields - Sun: photosphere -
catalogs
Abstract:
Long and consistent sunspot area records are important for
understanding long-term solar activity and variability. Multiple
observatories around the globe have regularly recorded sunspot areas,
but such individual records only cover restricted periods of time.
Furthermore, there are systematic differences between these records
and require cross-calibration before they can reliably be used for
further studies.
We produce a cross-calibrated and homogeneous record of total daily
sunspot areas, both projected and corrected, covering the period
between 1874 and 2019. In addition, we generated a catalog of
calibrated individual group areas for the same period.
We compared the data from nine archives: Royal Greenwich Observatory
(RGO), Kislovodsk, Pulkovo, Debrecen, Kodaikanal, Solar Optical
Observing Network (SOON), Rome, Catania, and Yunnan Observatories,
covering the period between 1874 and 2019. Cross-comparisons of the
individual records were done to produce homogeneous and
inter-calibrated records of daily projected and corrected areas. As in
earlier studies, the basis of the composite is formed by the data from
RGO. After 1976, the only datasets used are those from Kislovodsk,
Pulkovo, and Debrecen observatories. This choice was made based on the
temporal coverage and the quality of the data. While there are still
776 days missing in the final composite, these remaining gaps could
not be filled with data from the other archives as the missing days
lie either before 1922 or after 2016 and none of the additional
archives cover these periods.
In contrast to the SOON data used in previous area composites for the
post-RGO period, the properties of the data from Kislovodsk and
Pulkovo are very similar to those from the RGO series. They also
directly overlap the RGO data in time, which makes their
cross-calibration with RGO much more reliable. Indeed, comparing our
area catalog with previous such composites, we find improvements both
in data quality and coverage. We also computed the daily Photometric
Sunspot Index, which is widely used, for example, in empirical
reconstructions of solar irradiance.
Description:
A number of observatories around the globe have carried out
measurements of sunspot areas and positions over the last century.
RGO, the longest sunspot area database to date, started its campaign
in 1874 and after continuing for a century, stopped it in 1976.
Several other observatories from different parts of the world (e.g.,
Kodaikanal, Kislovodsk, Debrecen, Rome etc.) also carried out such
observing programs throughout the 20th century. Sunspot area datasets
are invaluable historical records of solar magnetic fields and are key
to understanding the solar variability and its historical
reconstructions.
In this work, we analyze and compare sunspot group areas from a total
of nine observatories (RGO, Kislovodsk, Pulkovo, Debrecen, Kodaikanal,
SOON, Rome, Catania, Yunnan). It turns out that data from only four
observatories (RGO, Kislovodsk, Pulkovo, Debrecen) are sufficient to
produce cross-calibrated, up-to-date (1874-2019) catalogs of daily
total and individual group areas. The remaining gaps (776 days in
total) could not be filled with data from the other archives as the
missing days lie either before 1922 or after 2016 and none of the
other archives cover these periods.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog1.dat 41 52353 Composite of daily total sunspot areas and
photometric sunspot index (PSI)
catalog2.dat 56 246096 Composite of individual sunspot areas
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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/599/A131 : Butterfly diagram wings (Leussu+, 2017)
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/ApJ/871/187 : Spot parameters on KIC solar-type stars (Namekata+, 2019)
Byte-by-byte Description of file: catalog1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Obs.date Observation date (YYYY/MM/DD)
12- 20 F9.3 --- Areap Calibrated daily total projected area
22 I1 --- f_Areap [1/5] Observatory flag to identify the
source of entry (G1)
24- 30 F7.2 --- Areac Calibrated daily total corrected area
32 I1 --- f_Areac [1/5] Observatory flag (G1)
34- 39 F6.4 --- PSI Daily PSI
41 I1 --- f_PSI [1/5] Observatory flag (G1)
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Byte-by-byte Description of file: catalog2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Obs.date Obaervation date
12- 16 A5 "h:m" Time Time of observation (hh:mm)
00:00 in case observatory does not provide
or a spot-less day
18- 25 F8.2 --- Areap Calibrated Projected group area
27- 33 F7.2 ---- Areac Calibrated Corrected group area
35- 40 F6.2 deg Lat Latitude (1)
42- 47 F6.2 deg Lon ? Longitude (1) (2)
49- 54 F6.3 --- r/R ?=99 Relative distance of sunspot group from
the center of solar disk in parts of
solar radius (r/R)
56 I1 --- Flag [1/5] Observatory flag to identify the
source of entry (G1)
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Note (1): -99 if observatory does not provide and 999 for spot-less days.
Note (2): For Kislovodsk data (observatory flag=2; see Col Flag) to May 2011,
the positional information (latitude and longitude) of each group is provided
only for the day of its first appearance. Hence, approximate longitude values
of a group on subsequent days, are derived using the available relative
distance information (see Col r/R).
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Global notes:
Note (G1): Flag as follows:
1 = RGO, factor (for projected) = 1, factor (for corrected) = 1
2 = Kislovodsk, factor (for projected) = 1.02, factor (for corrected) = 0.98
3 = Pulkovo, factor (for corrected) = 1.01
4 = Debrecen (1976-2015), factor (for projected) = 0.99,
factor (for corrected) = 1.06
5 = Debrecen (2016 onward), factor (for projected) = 0.99,
factor (for corrected) = 1.06)
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Acknowledgements:
Sudip Mandal, smandal.solar(at)gmail.com
(End) Patricia Vannier [CDS] 30-Apr-2020