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Maunder Minimum

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The Maunder minimum in a 400-year history of sunspot numbers

The Maunder Minimum, also known as the "prolonged sunspot minimum", is the name used for the period starting in about 1645 and continuing to about 1715 when sunspots became exceedingly rare, as noted by solar observers of the time, accompanied by lower than average temperatures.

The term was introduced after John A. Eddy[1] published a landmark 1976 paper in Science.[2] Astronomers before Eddy had also named the period after the solar astronomers Annie Russell Maunder (1868-1947) and E. Walter Maunder (1851–1928), who studied how sunspot latitudes changed with time.[3] The period the husband and wife team examined included the second half of the 17th century. Two papers were published in Edward Maunder's name in 1890[4] and 1894,[5] and he cited earlier papers written by Gustav Spörer.[6] Due to the social climate of the time, Annie's contribution was not publicly recognized.[7]

Spörer noted that, during one 28-year period within the Maunder Minimum (1672-1699), observations showed fewer than 50 sunspots, as opposed to a more typical 40,000–50,000 spots in modern times.[8]

Like the Dalton Minimum and Spörer Minimum, the Maunder Minimum coincided with a period of lower-than-average European temperatures.

Sunspot observations

The Maunder Minimum occurred between 1645 and 1715 when very few sunspots were observed. This was not due to a lack of observations; during the 17th century, Giovanni Domenico Cassini carried out a systematic program of solar observations at the Observatoire de Paris, thanks to the astronomers Jean Picard and Philippe de La Hire. Johannes Hevelius also performed observations on his own. The total numbers of sunspots (but not Wolf numbers) in different years were as follows[citation needed]:

Year Sunspots
1610 9
1620 6
1630 9
1640 0
1650 3
1660 Some sunspots reported by Jan Heweliusz in Machina Coelestis
1670 0
1680 1 huge sunspot observed by Giovanni Domenico Cassini

During the Maunder Minimum enough sunspots were sighted so that 11-year cycles could be extrapolated from the count. The maxima occurred in 1676, 1684, 1695, 1705 and 1716.

The sunspot activity was then concentrated in the southern hemisphere of the Sun, except for the last cycle when the sunspots appeared in the northern hemisphere, too.

According to Spörer's law, at the start of a cycle, spots appear at ever lower latitudes until they average at about latitude 15° at solar maximum. The average then continues to drift lower to about 7° and after that, while spots of the old cycle fade, new cycle spots start appearing again at high latitudes.

The visibility of these spots is also affected by the velocity of the sun's surface rotation at various latitudes:

Solar latitude Rotation period
(days)
0° 24.7
35° 26.7
40° 28.0
75° 33.0

Visibility is somewhat affected by observations being done from the ecliptic. The ecliptic is inclined 7° from the plane of the Sun's equator (latitude 0°).

Little Ice Age

Comparison of group sunspot numbers (top), Central England Temperature (CET) observations (middle) and reconstructions and modeling of Northern Hemisphere Temperatures (NHT). The CET in red are summer averages (for June, July and August) and in blue winter averages (for December of previous year, January and February). NHT in grey is the distribution from basket of paleoclimate reconstructions (darker grey showing higher probability values) and in red are from model simulations that account for solar and volcanic variations. By way of comparison, on the same scales the anomaly for modern data (after 31 December 1999) for summer CET is +0.65oC, for winter CET is +1.34oC, and for NHT is +1.08oC. Sunspot data are as in supplementary data to [9] and Central England Temperature data are as published by the UK Met Office [10] The NHT data are described in box TS.5, Figure 1 of the IPCC AR5 report of Working Group 1.[11]

The Maunder Minimum roughly coincided with the middle part of the Little Ice Age, during which Europe and North America experienced colder than average temperatures. Whether there is a causal relationship, however, is still controversial, as no convincing mechanism for the solar activity to produce cold temperatures has been proposed,[12] and the current best hypothesis for the cause of the Little Ice Age is that it was the result of volcanic action.[13][14] The onset of the Little Ice Age also occurred well before the beginning of the Maunder minimum.[13]

The correlation between low sunspot activity and cold winters in England has recently been analyzed using the longest existing surface temperature record, the Central England Temperature record.[15] They emphasize that this is a regional and seasonal effect relating to European winters, and not a global effect. A potential explanation of this has been offered by observations by NASA's Solar Radiation and Climate Experiment, which suggest that solar UV output is more variable over the course of the solar cycle than scientists had previously thought.[16] In 2011, an article was published in the Nature Geoscience journal that uses a climate model with stratospheric layers and the SORCE data to tie low solar activity to jet stream behavior and mild winters in some places (southern Europe and Canada/Greenland) and colder winters in others (northern Europe and the United States).[17] In Europe, examples of very cold winters are 1683-4, 1694-5, and the winter of 1708–9.[18] In such years, River Thames frost fairs were held.

However the Thames ceased to freeze in the 19th century largely because the removal of the "Old" (medieval) London Bridge in 1825 dramatically increased the river's flow into the Pool of London. The original 240–270-metre (800–900 ft) bridge stood upon 19 irregularly spaced arches that were set into the river bed on large starlings. It acted as a weir holding back the slack upstream waters from the tidal brackish, salt water downstream. The construction of Thames Embankment (began 1862) further increased the river's hydrological flow by narrowing the width of waterway through the centre of capital.[original research?]

Note that the term "Little Ice Age" applied to the Maunder minimum is something of a misnomer as it implies a period of unremitting cold (and on a global scale), which is not the case. For example, the coldest winter in the Central England Temperature record is 1683-4, but the winter just 2 years later (both in the middle of the Maunder minimum) was the fifth warmest in the whole 350-year CET record. Furthermore, summers during the Maunder minimum were not significantly different to those seen in subsequent years. The drop in global average temperatures in paleoclimate reconstructions at the start of the Little Ice Age was between about 1560 and 1600, whereas the Maunder minimum began almost 50 years later.[original research?]

Other observations

Solar activity events recorded in radiocarbon.
Graph showing proxies of solar activity, including changes in sunspot number and cosmogenic isotope production.

Past solar activity may be recorded by various proxies including carbon-14 and beryllium-10.[19] These indicate lower solar activity during the Maunder Minimum. The scale of changes resulting in the production of carbon-14 in one cycle is small (about one percent of medium abundance) and can be taken into account when radiocarbon dating is used to determine the age of archaeological artifacts. The interpretation of the beryllium-10 and carbon-14 cosmogenic isotope abundance records stored in terrestrial reservoirs such as ice sheets and tree rings has been greatly aided by reconstructions of solar and heliospheric magnetic fields based on historic data on Geomagnetic storm activity, which bridge the time gap between the end of the usable cosmogenic isotope data and the start of modern spacecraft data.[20][21]

Other historical sunspot minima have been detected either directly or by the analysis of the cosmogenic isotopes; these include the Spörer Minimum (1450–1540), and less markedly the Dalton Minimum (1790–1820). In a 2012 study, sunspot minima have been detected by analysis of carbon-14 in lake sediments.[22] In total there seem to have been 18 periods of sunspot minima in the last 8,000 years, and studies indicate that the sun currently spends up to a quarter of its time in these minima.

A paper based on an analysis of a Flamsteed drawing, suggests that the Sun's surface rotation slowed in the deep Maunder minimum (1684).[23]

During the Maunder Minimum aurorae had been observed seemingly normally, with a regular decadal-scale cycle.[24][25] This is somewhat surprising because the later, and less deep, Dalton sunspot minimum is clearly seen in auroral occurrence frequency, at least at lower geomagnetic latitudes.[26] Because geomagnetic latitude is an important factor in auroral occurrence, (lower-latitude aurorae requiring higher levels of solar-terrestrial activity) it becomes important to allow for population migration and other factors that may have influenced the number of reliable auroral observers at a given magnetic latitude for the earlier dates.[27] Decadal-scale cycles during the Maunder minimum can also be seen in the abundances of the beryllium-10 cosmogenic isotope (which unlike carbon-14 can be studied with annual resolution) [28] but these appear to be in antiphase with any remnant sunspot activity. An explanation in terms of solar cycles in loss of solar magnetic flux was proposed in 2012.[29]

The fundamental papers on the Maunder minimum (Eddy, Legrand, Gleissberg, Schröder, Landsberg et al.) have been published in Case studies on the Spörer, Maunder and Dalton Minima.[30]

See also

References

  1. ^ Bruce Weber, John A. Eddy, Solar Detective, Dies at 78, New York Times, June 17, 2009 (retrieved 28 July 2015)
  2. ^ Eddy J.A. (June 1976). "The Maunder Minimum". Science. 192 (4245): 1189–1202. Bibcode:1976Sci...192.1189E. doi:10.1126/science.192.4245.1189. PMID 17771739. PDF Copy
  3. ^ Who named the Maunder Minimum?
  4. ^ E.W.M. (1890) "Professor Spoerer's researches on sun-spots," Monthly Notices of the Royal Astronomical Society, 50 : 251-252.
  5. ^ E. Walter Maunder (August 1, 1894) "A prolonged sunspot minimum," Knowledge, 17 : 173-176.
  6. ^ See:
  7. ^ http://www.underthemicroscope.com/notable-irish-scientist-annie-maunder-the-lady-computer/
  8. ^ John E. Beckman and Terence J. Mahoney. "The Maunder Minimum and Climate Change: Have Historical Records Aided Current Research?". Astronomical Society of the Pacific.
  9. ^ Lockwood, M.; et al. (July 2014). "Centennial variations in sunspot number, open solar flux and streamer belt width: 2. Comparison with the geomagnetic data". J. Geophys. Res. 119 (7): 5183–5192. Bibcode:2014JGRA..119.5183L. doi:10.1002/2014JA019972. PDF Copy
  10. ^ "Hadley Centre Central England Temperature (HadCET) dataset".
  11. ^ "Climate Change 2013, The Physical Science Basis, WG1, 5th Assessment Report, IPCC".
  12. ^ Plait, Phil, Are we headed for a new ice age?, Discover, June 17, 2011 (retrieved 16 July 2015)
  13. ^ a b Miller et al. 2012. "Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks" Geophysical Research Letters 39, 31 January; see press release on AGU website (retrieved 16 July 2015).
  14. ^ Was the Little Ice Age Triggered by Massive Volcanic Eruptions? ScienceDaily, 30 January 2012 (accessed 21 May 2012)
  15. ^ Lockwood, M.; et al. (February 2010). "Are cold winters in Europe associated with low solar activity?". Env. Res. Lett. 5 (2): 024001. Bibcode:2010ERL.....5b4001L. doi:10.1088/1748-9326/5/2/024001. PDF Copy
  16. ^ Harder, J.A.; et al. (April 2009). "Trends in solar spectral irradiance variability in the visible and infrared". Geophys. Res. Lett. 36 (7): L07801. Bibcode:2009GeoRL..36.7801H. doi:10.1029/2008GL036797.
  17. ^ Ineson, S.; et al. (October 2011). "Solar forcing of winter climate variability in the Northern Hemisphere". Nature Geoscience. 4: 753–757. Bibcode:2011NatGe...4..753I. doi:10.1038/ngeo1282.
  18. ^ Niles' Weekly Register, Volume 15, Supplement, History of the Weather
  19. ^ Usoskin I.G. (2008). "A History of Solar Activity over Millennia". Living Reviews in Solar Physics. 5 (3). doi:10.12942/lrsp-2008-3.{{cite journal}}: CS1 maint: unflagged free DOI (link) PDF Copy
  20. ^ Lockwood M.; et al. (June 1999). "A doubling of the sun's coronal magnetic field during the last 100 years". Nature. 399: 437–439. Bibcode:1999Natur.399..437L. doi:10.1038/20867. PDF Copy
  21. ^ Lockwood M. (2013). "Reconstruction and Prediction of Variations in the Open Solar Magnetic Flux and Interplanetary Conditions". Living Reviews in Solar Physics. 10 (4). Bibcode:2013LRSP...10....4L. doi:10.12942/lrsp-2013-4.{{cite journal}}: CS1 maint: unflagged free DOI (link) PDF Copy
  22. ^ Celia Martin-Puertas, Katja Matthes, Achim Brauer, Raimund Muscheler, Felicitas Hansen, Christof Petrick, Ala Aldahan, Göran Possnert & Bas van Geel (April 2, 2012). "Regional atmospheric circulation shifts induced by a grand solar minimum". Nature Geoscience. 5 (6): 397–401. Bibcode:2012NatGe...5..397M. doi:10.1038/ngeo1460.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  23. ^ Vaquero JM, Sánchez-Bajo F, Gallego MC (2002). "A Measure of the Solar Rotation During the Maunder Minimum". Solar Physics. 207 (2): 219–222. Bibcode:2002SoPh..207..219V. doi:10.1023/A:1016262813525.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  24. ^ Schröder, Wilfried (1992). "On the existence of the 11-year cycle in solar and auroral activity before and during the Maunder Minimum". Journal of Geomagnetism and Geoelectricity. 44 (2): 119–28. doi:10.5636/jgg.44.119. ISSN 0022-1392.
  25. ^ Legrand, JP; Le Goff, M; Mazaudier, C; Schröder, W (1992). "Solar and auroral activities during the seventeenth century". Acta Geodaetica et Geophysica Hungarica. 27 (2–4): 251–282.
  26. ^ Nevanlinna, H. (1995). "Auroral observations in Finland - Visual sightings during the 18th and 19th centuries". Journal of Geomagnetism and Geoelectricity. 47 (10): 953–960. doi:10.5636/jgg.47.953. ISSN 0022-1392. PDF Copy
  27. ^ Vázquez, M.; et al. (2014). "Long-term Spatial and Temporal Variations of Aurora Borealis Events in the Period 1700 – 1905". Solar Physics. 289 (5): 1843–1861. arXiv:1309.1502. Bibcode:2014SoPh..289.1843V. doi:10.1007/s11207-013-0413-6. ISSN 0038-0938. PDF Copy
  28. ^ Beer, J.; et al. (1988). "An Active Sun Throughout the Maunder Minimum". Solar Physics. 181 (1): 237–249. Bibcode:1998SoPh..181..237B. doi:10.1023/A:1005026001784. PDF Copy
  29. ^ Owens, M.J..; et al. (2012). "Heliospheric modulation of galactic cosmic rays during grand solar minima: Past and future variations". Geophys. Res. Lett. 39 (19): L19102. Bibcode:2012GeoRL..3919102O. doi:10.1029/2012GL053151. PDF Copy
  30. ^ Schröder, Wilfried (2005). Case studies on the Spörer, Maunder, and Dalton minima. Beiträge zur Geschichte der Geophysik und Kosmischen Physik. Vol. 6. Potsdam: AKGGP, Science Edition.

Further reading

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