Solar maximum or solar max is a regular period of greatest Sun activity during the 11-year solar cycle. During solar maximum, large numbers of sunspots appear, and the solar irradiance output grows by about 0.07%.
At solar maximum, the Sun's magnetic field lines are the most distorted due to the magnetic field on the solar equator rotating at a slightly faster pace than at the solar poles. On average, the solar cycle takes about 11 years to go from one solar maximum to the next, with duration observed varying from 9 to 14 years.
Large solar flares often occur during a maximum. For example, the solar storm of 1859 struck the Earth with such intensity that the northern lights were visible as far from the poles as Cuba and Hawaii.
Predictions of a future maximum's timing and strength are very difficult; predictions vary widely. There was a solar maximum in 2000. In 2006, NASA initially expected a solar maximum in 2010 or 2011, and thought that it could be the strongest since 1958. However, the solar maximum was not declared to have occurred until 2014, and even then was ranked among the weakest on record.
Grand solar minima and maxima
Grand solar maxima occur when several solar cycles exhibit greater than average activity for decades or centuries. Solar cycles still occur during these grand solar maximum periods, but the intensity of those cycles is greater. Grand solar maxima have shown some correlation with global and regional climate changes.
|Homeric minimum ||950BC||800BC|
|Oort minimum (see Medieval Warm Period)||1040||1080|
|Medieval maximum (see Medieval Warm Period)||1100||1250|
The idea of a Modern Maximum has now been thrown into question with the release of a paper at the International Astronomical Union General Assembly in August 2015.
A list of historical Grand minima of solar activity includes also Grand minima ca. 690 AD, 360 BC, 770 BC, 1390 BC, 2860 BC, 3340 BC, 3500 BC, 3630 BC, 3940 BC, 4230 BC, 4330 BC, 5260 BC, 5460 BC, 5620 BC, 5710 BC, 5990 BC, 6220 BC, 6400 BC, 7040 BC, 7310 BC, 7520 BC, 8220 BC, 9170 BC. There was also the maunder minimum 1645 to 1715.
- C. D. Camp & K. K. Tung (2007). "Surface warming by the solar cycle as revealed by the composite mean difference projection" (PDF). Geophysical Research Letters. 34 (14): L14703. Bibcode:2007GeoRL..3414703C. doi:10.1029/2007GL030207. Retrieved 20 January 2012.
- "Solar Storm Warning", Science@NASA, 10 March 2006, Accessed 26 Mar. 2010
- "Solar Mini-Max". NASA. Retrieved 2014-12-24.
- Celia Martin-Puertas; Katja Matthes; Achim Brauer; Raimund Muscheler; et al. (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.
- "Corrected Sunspot History Suggests Climate Change since the Industrial Revolution not due to Natural Solar Trends". Press release. IAU. 7 Aug 2015. 1508.
- Usoskin, Ilya G.; Solanki, Sami K.; Kovaltsov, Gennady A. (2007). "Grand minima and maxima of solar activity: new observational constraints" (PDF). Astron. Astrophys. 471 (1): 301–9. arXiv:0706.0385. Bibcode:2007A&A...471..301U. doi:10.1051/0004-6361:20077704.