Dalton Minimum

The Dalton minimum in the 400 year history of sunspot numbers

The Dalton Minimum was a period of low solar activity, named after the English meteorologist John Dalton, lasting from about 1790 to 1830. Like the Maunder Minimum and Spörer Minimum, the Dalton Minimum coincided with a period of lower-than-average global temperatures. The Oberlach Station in Germany, for example, experienced a 2.0°C decline over 20 years.

The precise cause of the lower-than-average temperatures during this period is not well understood. Recent papers have suggested that a rise in volcanism was largely responsible for the cooling trend.

While The Year Without a Summer, in 1816, occurred during the Dalton Minimum the prime reason for that particular cold spike was the eruption of a Super Colossal Volcano named Mount Tambora in Indonesia which was (jointly) one of the 2 largest eruptions in the past 2000 years.

References

• Komitov Boris and Vladimir Kaftan (2004) "The Sunspot Activity in the Last Two Millenia on the Basis of Indirect and Instrumental Indexes: Time Series Models and Their Extrapolations for the 21st Century", in Proceedings of the International Astronomical Union, 2004, pp. 113-114.
• Wagner, Sebastian and Eduardo Zorita (2005) "The influence of volcanic, solar and CO2 forcing on the temperatures in the Dalton Minimum (1790–1830): a model study", Climate Dynamics v. 25, pp. 205–218, doi 10.1007/s00382-005-0029-0.
• Wilson, Robert M. (nd) "Volcanism, Cold Temperature, and Paucity of Sunspot Observing Days (1818-1858): A Connection?", The Smithsonian/NASA Astrophysics Data System, accessed February 2009.

Further reading

A detailed analysis with the auroral and solar data has been given by Wilfried Schröder, N. N. Shefov in a paper in Ann. Geophys. 2004. Also details can be found in Wilfried Schröder, Das Phänomen des Polarlichts (The Aurora in Time), Darmstadt, Wissenschaftliche Buchgeselllschaft 1984, and Science Edition, Bremen, 2000.