At this year's Fall Meeting of American Geophysical Union, held in San Francisco (December 9 - 13), several scientists made a presentation on weak Solar Cycle 24 and its consequences.
They agree that the current solar cycle is on track to be the weakest in 100 years and are saying this is providing an unprecedented opportunity for studying the Sun. While the weakening trend is not new for the Sun, it is new and interesting for scientists who observe and measure it today.
In this panel, scientists examined the current solar cycle in relation to past cycles and discuss the consequences of the weak solar cycle on the various layers regions between the Sun and Earth, including implications for space weather, atmosphere and climate.
Video courtesy: AGU 2013. December 11, 2013
- Current solar maximum conditions are substantially weaker than prior maximum in 2002
- In 2002 CO2 and NO emitted 2 Trillion more kWh of infrared energy than in 2013
Bee sure to check PDF files used in the presentations. Source: AGU
Nat Gopalswamy, astrophysicist, Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA;
Leif Svalgaard, senior research scientist, W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, California, USA;
Marty Mlynczak, senior research scientist, Climate Science Branch, NASA Langley Research Center, Hampton, Virginia, USA;
Joe Giacalone, professor and associate director, Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA.
Image below shows observed and predicted active regions/sunspots count for Solar Cycle 22, 23 and 24 (1980 - 2020).
Solar cycle 24 is begining to look like Solar cycle 14 (February 1902 - August 1913). The maximum smoothed sunspot number (monthly number of sunspots averaged over a twelve-month period) observed during the solar cycle was 64.2, and the minimum was 1.5. There were a total of approximately 1019 days with no sunspots during that cycle. Source of data: SIDC
The following image shows a graph with data from 400 years of sunspot observations (1600 - 2000):
Author: Robert A. Rohde
Since c. 1749, continuous monthly averages of sunspot activity have been available and are shown here as reported by the Solar Influences Data Analysis Center, World Data Center for the Sunspot Index, at the Royal Observatory of Belgium.
These figures are based on an average of measurements from many different observatories around the world. Prior to 1749, sporadic observations of sunspots are available. These were compiled and placed on consistent monthly framework by Hoyt & Schatten (1998a, 1998b).
The most prominent feature of this graph is the c. 11 year solar magnetic cycle which is associated with the natural waxing and waning of solar activity. On longer time scales, the Sun has shown considerable variability, including the long Maunder Minimum when almost no sunspots were observed, the less severe Dalton Minimum, and increased sunspot activity during the last fifty years, known as the Modern Maximum.
The causes for these variations are not well understood, but because sunspots and associated faculae affect the brightness of the sun, solarluminosity is lower during periods of low sunspot activity. It is widely believed that the low solar activity during the Maunder Minimum may be among the principal causes of the Little Ice Age. For example, during the 70-year period from 1645 to 1715, few, if any, sunspots were seen, even during expected sunspot maximums. Western Europe entered a climate period known as the "Maunder Minimum" or "Little Ice Age." Temperatures dropped by 1.8 to 2.7 degrees Fahrenheit.
Featured image: NASA. Edit: The Watchers