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Dalton Minimum

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The Dalton minimum in the 400-year history of sunspot numbers

The Dalton Minimum was a period of low sunspot count, representing low solar activity, named after the English meteorologist John Dalton, lasting from about 1790 to 1830[1] or 1796 to 1820,[2] corresponding to the period solar cycle 4 to solar cycle 7. While the Dalton Minimum is often compared with the Maunder Minimum, its sunspot number was slightly higher and reported sunspots distributed in both solar hemispheres unlike the Maunder Minimum.[3] The coronal streamers are visually confirmed in Ezra Ames and José Joaquin de Ferrer’s eclipse drawings in 1806 and indicates similarity of its magnetic field not with that of the Maunder Minimum but with that of the modern solar cycles.[4]

Temperature

Like the Maunder Minimum and Spörer Minimum, the Dalton Minimum coincided with a period of lower-than-average global temperatures. During that period, there was a variation of temperature of about 1 °C in Germany.[5]

The cause of the lower-than-average temperatures and their possible relation to the low sunspot count are not well understood. Recent papers have suggested that a rise in volcanism was largely responsible for the cooling trend.[6]

While the Year Without a Summer, in 1816, occurred during the Dalton Minimum, the prime reason for that year's cool temperatures was the highly explosive eruption the previous year of Mount Tambora in Indonesia, which was one of the two largest eruptions in the past 2000 years. One must also consider that the rise in volcanism may have been triggered by lower levels of solar output as there is a weak but statistically significant link between decreased solar output and an increase in volcanism."Pubs.GISS: Stothers 1989: Volcanic eruptions and solar activity". "A dimmer sun (due to a non-grand, prolonged solar minimum like the Dalton) could have helped spread or move the center of the North Atlantic low-pressure system sufficiently southward from Iceland to the British Isles to intensify volcanic dust and aerosol effects from Tambora. Cool polar air also could have penetrated farther south toward eastern North America in the Dalton Minimum...Recent research by Tim Ball, Mike Chenoweth,(and) Dick Harrington...has expanded the recording of anomalous conditions in 1816 to Greenland, Alaska, northeast Brazil, the tropical Atlantic, the eastern Pacific...India, Tibet, South Africa, and elsewhere." [7]

See also

Notes

  1. ^ Komitov and Kaftan 2004
  2. ^ Archibald, p. 32
  3. ^ Hayakawa et al. 2020a
  4. ^ Hayakawa et al. 2020b
  5. ^ File:Temperaturreihe Deutschland.png, red line, 1795 to 1815
  6. ^ Wagner and Zorita, as well as Wilson.
  7. ^ Soon, W., and Yaskell, S.H., Year Without a Summer, Mercury, Astronomical Society of the Pacific, Vol. 32, No. 3, May/June, 2003.

References