The solar cycle, or the solar magnetic activity cycle, is a periodic change in the amount of irradiation from the sun that is experienced on Earth. It has a period of about 11 years, and is one component of solar variation, the other being aperiodic fluctuations. Solar variation causes changes in space weather and to some degree weather and climate on Earth. The cycle is observed by counting the frequency and placement of sunspots visible on the Sun. Powered by a hydromagnetic dynamo process, driven by the inductive action of internal solar flows, the solar cycle:

Structures the Sun's atmosphere, its corona and the wind;

Modulates the solar irradiance;

Modulates the flux of short-wavelength solar radiation, from ultraviolet to X-ray;

Modulates the occurrence frequency of solar flares, coronal mass ejections, and other geoeffective solar eruptive phenomena;

Indirectly modulates the flux of high-energy galactic cosmic rays entering the solar system.

History

The solar cycle was discovered in 1843 by Samuel Heinrich Schwabe, who after 17 years of observations noticed a periodic variation in the average number of sunspots seen from year to year on the solar disk. Rudolf Wolf compiled and studied these and other observations, reconstructing the cycle back to 1745, eventually pushing these reconstructions to the earliest observations of sunspots by Galileo and contemporaries in the early seventeenth century. Starting with Wolf, solar astronomers have found it useful to define a standard sunspot number index, which continues to be used today.

Until recently it was thought that there were 28 cycles in the 309 years between 1699 and 2008, giving an average length of 11.04 years, but recent research has showed that the longest of these (1784–99) seems actually to have been two cycles, so that the average length is only around 10.66 years. Cycles as short as 9 years and as long as 14 years have been observed. Significant variations in amplitude also occur. Solar maximum and solar minimum refer respectively to epochs of maximum and minimum sunspot counts. Individual sunspot cycles are partitioned from one minimum to the next.

Following the numbering scheme established by Wolf, the 1755–1766 cycle is traditionally numbered "1". The period between 1645 and 1715, a time during which very few sunspots were observed, is a real feature, as opposed to an artifact due to missing data, and coincides with the Little Ice Age. This epoch is now known as the Maunder minimum, after Edward Walter Maunder, who extensively researched this peculiar event, first noted by Gustav Spörer. In the second half of the nineteenth century it was also noted (independently) by Richard Carrington and by Spörer that as the cycle progresses, sunspots appear first at mid-latitudes, and then closer and closer to the equator until solar minimum is reached. This pattern is best visualized in the form of the so-called butterfly diagram, first constructed by the husband-wife team of E. Walter and Annie Maunder in the early twentieth century (see graph below). Images of the Sun are divided into latitudinal strips, and the monthly-averaged fractional surface of sunspots calculated. This is plotted vertically as a color-coded bar, and the process is repeated month after month to produce this time-latitude diagram.

The physical basis of the solar cycle was elucidated in the early twentieth century by George Ellery Hale and collaborators, who in 1908 showed that sunspots were strongly magnetized (this was the first detection of magnetic fields outside the Earth), and in 1919 went on to show that the magnetic polarity of sunspot pairs:

Is always the same in a given solar hemisphere throughout a given sunspot cycle;

Is opposite across hemispheres throughout a cycle;

Reverses itself in both hemispheres from one sunspot cycle to the next.

Hale's observations revealed that the solar cycle is a magnetic cycle with an average duration of 22 years. However, because very nearly all manifestations of the solar cycle are insensitive to magnetic polarity, it remains common usage to speak of the "11-year solar cycle".

Half a century later, the father-and-son team of Harold Babcock and Horace Babcock showed that the solar surface is magnetized even outside of sunspots; that this weaker magnetic field is to first order a dipole; and that this dipole also undergoes polarity reversals with the same period as the sunspot cycle (see graph below). These various observations established that the solar cycle is a spatiotemporal magnetic process unfolding over the Sun as a whole.

Phenomena, measurement, and causes

Spots from multiple cycles can co-exist for some time and since it was discovered the sun reverses magnetic polarity one solar half cycle to the next, spots from different cycles can be told apart. However it takes some months before a definite decision to be made on the true date of solar minimum, which is announced by the relevant expert authorities.

One of the main authorities is SIDC (the Solar Influences Data Analysis Center) which is located in Belgium, and works with agencies such as NASA and ESA.

The most important information today comes from SOHO (a project of international cooperation between ESA and NASA), such as the MDI magnetogram, where the solar "surface" magnetic field can be seen.

The basic causes of the solar variability and solar cycles are still under debate, with some researchers suggesting a link with the tidal forces due to the gas giants Jupiter and Saturn, or due to the solar inertial motion. Another cause of sun spots can be solar jet stream "torsional oscillation".

Effects of the solar cycle

The Sun's magnetic field structures its atmosphere and outer layers all the way through the corona and into the solar wind. Its spatiotemporal variations lead to a host of phenomena collectively known as solar activity. All of solar activity is strongly modulated by the solar magnetic cycle, since the latter serves as the energy source and dynamical engine for the former.

Surface magnetism

Sunspots may exist anywhere from a few days to a few months, but they eventually decay, and this releases magnetic flux in the solar photosphere. This magnetic field is dispersed and churned by turbulent convection, and solar large-scale flows. These transport mechanisms lead to the accumulation of the magnetized decay products at high solar latitudes, eventually reversing the polarity of the polar fields (notice how the blue and yellow fields reverse in the graph above).

The dipolar component of the solar magnetic field is observed to reverse polarity around the time of solar maximum, and reaches peak strength at the time of solar minimum. Sunspots, on the other hand, are produced from a strong toroidal (longitudinally-directed) magnetic field within the solar interior. Physically, the solar cycle can be thought of as a regenerative loop where the toroidal component produces a poloidal field, which later produces a new toroidal component of sign such as to reverse the polarity of the original toroidal field, which then produces a new poloidal component of reversed polarity, and so on.

Solar irradiance

The total solar irradiance (TSI) is the amount of solar radiative energy incident on the Earth's upper atmosphere. TSI variations were undetectable until satellite observations began in late 1978. The major finding of satellite observations is that TSI varies in phase with the solar magnetic activity cycle with an amplitude of about 0.1% and an average value of about 1366 W/m². Variations about the average up to −0.3% are caused by large sunspot groups and of +0.05% by large faculae and bright network on a week to 10 day timescale. (see TSI variation graphics.) The sunspot cycle variation of 0.1% has small but detectable effects on the Earth's climate. TSI variations over the several decades of continuous satellite observation show small but detectable trends.

TSI is higher at solar maximum, even though sunspots are darker (cooler) than the average photosphere. This is caused by magnetized structures other than sunspots during solar maxima, such as faculae and active elements of the "bright" network, that are brighter (hotter) than the average photosphere. They collectively overcompensate for the irradiance deficit associated with the cooler but less numerous sunspots. The primary driver of TSI changes on solar rotational and sunspot cycle timescales is the varying photospheric coverage of these radiatively active solar magnetic structures.

Short-wavelength radiation

With a temperature of 5870 kelvins, the photosphere of the Sun emits very little short-wavelength radiation, such as extreme ultraviolet (EUV) and X-rays. However, hotter upper layers of the Sun's atmosphere (chromosphere and corona) emit more short-wavelength radiation. Since the upper atmosphere is not homogeneous and contains significant magnetic structure, the solar UV, EUV and X-ray flux varies markedly in the course of the solar cycle.

The photo montage to the left illustrates this variation for soft X-ray, as observed by the Japanese satellite Yohkoh from after August 30, 1991, at the peak of cycle 22, to September 6, 2001, at the peak of cycle 23. Similar cycle-related variations are observed in the flux of solar UV or EUV radiation, as observed, for example, by the SOHO or TRACE satellites.

Even though it only accounts for a minuscule fraction of total solar radiation, the impact of solar UV, EUV and X-ray radiation on the Earth's upper atmosphere is profound. Solar UV flux is a major driver of stratospheric chemistry, and increases in ionizing radiation significantly affect ionosphere-influenced temperature and electrical conductivity.

Solar radio flux

Emission from the Sun at centimetric (radio) wavelength is due primarily to coronal plasma trapped in the magnetic fields overlying active regions. The F10.7 index is a measure of the solar radio flux per unit frequency at a wavelength of 10.7 cm, near the peak of the observed solar radio emission. F10.7 is often expressed in SFU or solar flux units. It represents a measure of diffuse, nonradiative heating of the coronal plasma trapped by magnetic fields over active regions, and is an excellent indicator of overall solar activity levels. The solar F10.7 cm record extends back to 1947, and is the longest direct record of solar activity available, other than sunspot-related quantities.

Sunspot activity has a major effect on long distance radio communications particularly on the shortwave bands although medium wave and low VHF frequencies are also affected. High levels of sunspot activity lead to improved signal propagation on higher frequency bands, although they also increase the levels of solar noise and ionospheric disturbances. These effects are caused by impact of the increased level of solar radiation on the ionosphere.

It has been proposed that 10.7 cm solar flux can interfere with point-to-point terrestrial communications.

Geoeffective eruptive phenomena

The solar magnetic field structures the corona, giving it its characteristic shape visible at times of solar eclipses. Complex coronal magnetic field structures evolve in response to fluid motions at the solar surface, and emergence of magnetic flux produced by dynamo action in the solar interior. For reasons not yet understood in detail, sometimes these structures lose stability, leading to coronal mass ejections into interplanetary space, or flares, caused by sudden localized release of magnetic energy driving copious emission of ultraviolet and X-ray radiation as well as energetic particles. These eruptive phenomena can have a significant impact on Earth's upper atmosphere and space environment, and are the primary drivers of what is now called space weather.

The occurrence frequency of coronal mass ejections and flares is strongly modulated by the solar activity cycle. Flares of any given size are some 50 times more frequent at solar maximum than at minimum. Large coronal mass ejections occur on average a few times a day at solar maximum, down to one every few days at solar minimum. The size of these events themselves does not depend sensitively on the phase of the solar cycle. A good recent case in point are the three large X-class flares having occurred in December 2006, very near solar minimum; one of these (an X9.0 flare on Dec 5) stands as one of the brightest on record.

Cosmic ray flux

The outward expansion of solar ejecta into interplanetary space provides overdensities of plasma that are efficient at scattering high-energy cosmic rays entering the solar system from elsewhere in the galaxy. Since the frequency of solar eruptive events is strongly modulated by the solar cycle, the degree of cosmic ray scattering in the outer solar system varies in step. As a consequence, the cosmic ray flux in the inner solar system is anticorrelated with the overall level of solar activity. This anticorrelation is clearly detected in cosmic ray flux measurements at the Earth's surface. Some high-energy cosmic rays entering Earth's atmosphere collide hard enough with molecular atmospheric constituents to cause occasionally nuclear spallation reactions. Some of the fission products include radionuclides such as ¹⁴C and ¹⁰Be, which settle down on Earth's surface. Their concentration can be measured in ice cores, allowing a reconstruction of solar activity levels into the distant past. Such reconstructions indicate that the overall level of solar activity since the middle of the twentieth century stands amongst the highest of the past 10,000 years, and that Maunder minimum-like epochs of suppressed activity, of varying durations have occurred repeatedly over that time span.

Effects on Earth

Terrestial organisms

The impact of Solar cycle on living organisms has been investigated (see chronobiology). Some researchers claim to have found connections with human health.

The amount of UVB light at 300 nm reaching the Earth varies by as much as 400% over the solar cycle due to variations in the protective ozone layer. In the stratosphere, ozone is continuously regenerated by the splitting of O₂ molecules by ultraviolet light. During a solar minimum, the decrease in ultraviolet light received from the Sun leads to a decrease in the concentration of ozone, allowing increased UVB to penetrate to the Earth's surface.

Radio communication

Skywave modes of radio communication operate by bending (refracting) radio waves (electromagnetic radiation) through the Ionosphere. During the "peaks" of the solar cycle, the ionosphere becomes increasingly ionized by solar photons and cosmic rays. This affects the path (propagation) of the radio wave in complex ways which can both facilitate or hinder local and long distance communications. Forecasting of skywave modes is of considerable interest to commercial marine and aircraft communications, amateur radio operators, and shortwave broadcasters. These users utilize frequencies within the High Frequency or 'HF' radio spectrum which are most affected by these solar and ionospheric variances. Changes in solar output affect the maximum usable frequency, a limit on the highest frequency usable for communications.

Terrestrial climate

The recent rise in global temperature is too large to be caused solely by recent changes in solar luminosity, but a link has been found between solar cycles, global climate and events like El Nino, and a study shows that heat caused by El Nino has a relation to civil wars.

Observations have shown correlations between the length of the solar cycle and observed (or proxy-calculated) atmospheric temperature on the earth.

The most well-documented connection between solar activity and climate change is the Maunder Minimum, during which cold weather prevailed in Europe. Research suggests a new 90-year Maunder minimum would result in a reduction of global average temperatures of about 0.3°C, which would not be enough to offset the ongoing and forecasted average global temperature increase due to global warming.

Daniel J. Hancock and Douglas N. Yarger found "statistically significant relationships between the double [~21 year] sunspot cycle and the 'January thaw' phenomenon along the East Coast and between the double sunspot cycle and 'drought' (June temperature and precipitation) in the Midwest."

Forecast of solar activity

In view of the problems in space flight occurring during high solar activity prediction of the latter becomes more and more important, A particular method that relies on several consecutive cycles was estyblished by Wolfgang Gleißberg.

See also

List of solar cycles

Climate cycles

Sunspot

References

External links

Satellite Total Solar Irradiance Observations

SolarCycle24.com

Great Moments in the History of Solar Physics

Solar Physics Web Pages at NASA's Marshall Space Flight Center

Science Briefs: Do Variations in the Solar Cycle Affect Our Climate System?. By David Rind, NASA GISS, January 2009

Yohkoh Public Outreach Project

HAO Educational pages

Stanford Solar Center

Cosmos

Windows to the Universe: The Sun

SOHO Web Site

TRACE Web Site

Solar Influences Data Analysis Center

KN4LF Solar Space Weather & Geomagnetic Data Archive Site

Propagation Service Center

Animated explanation of the effect of the Solar Cycle on Sunspots in the Photosphere (University of Glamorgan)

Category:Stellar phenomena Cycle

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Coordinates	28°36′50″N77°12′32″N
name	Alfred Lambremont Webre
birth date	May 24, 1942
birth place	Pensacola, Florida
education	Yale UniversityYale Law SchoolUniversity of Texas at Brownsville
occupation	AuthorLawyerFuturistPeace ActivistEnvironmental ActivistSpace Activist
spouse	Geri DiStefano Webre
children	}}

Alfred Lambremont Webre, J.D., M.Ed. (b. May 24, 1942 on a U.S. Naval Air Station) is an author, lawyer (member of the District of Columbia Bar), futurist, peace activist, environmental activist, and a space activist who promotes the ban of space weapons. He was a co-architect of the Space Preservation Treaty and the Space Preservation Act that was introduced to the U.S. Congress by Congressman Dennis Kucinich and is endorsed by more than 270 NGO's worldwide. He helped draft the Citizen Hearing in 2000 with Stephen Bassett and serves as a member of the Board of Advisors. Webre is also on the Board of Advisers at the New Energy Movement, is the congressional coordinator for The Disclosure Project, is a judge on the Kuala Lumpur War Crimes Tribunal, and is the Chairman the Mars Anomaly Research Society (MARS).

Biography

Webre comes from a family which settled in Louisiana in the 17th century. One of his parents is Cuban and Alfred Webre was raised in Cuba.

Education

Webre entered Yale University in 1960 and graduated in 1964 with a Bachelor of Science in Industrial Administration Honors. His interest in law brought him to continue his education and to graduate from Yale Law School with a Juris Doctor in International law in 1967. While studying at Yale Law School, he was also an Assistant in Instruction at the Economics Department of the U.S. Federal Taxation at Yale University (1965–1967). In 1967-1968, Webre traveled to Montevideo, Uruguay and became a Fulbright Scholar in Economic Integration. In 1993, he entered the University of Texas at Brownsville and graduated with a Master of Education in Counseling in 1997.

Early career

Webre became an associate with Cleary, Gottlieb, Steen & Hamilton, in New York City, in 1968. His responsibilities were international finance, tax, and litigation practice for investment banking, corporate, and public sector clients. In 1970, he joined the New York City Environmental Protection Administration as the General Counsel and Assistant Administrator. He designed and enforced environmental standards for air, water, noise pollution, and solid waste management. In 1973, he went to work as a consultant for the Ford Foundation’s Public Interest Environmental Law Program in New York City. He was in charge of evaluation and program recommendations in public interest environmental law program for grantees including Natural Resources Defense Council and Environmental Defense Fund. In 1977, he joined Stanford Research Institute (SRI International) in Menlo Park, California, as a futurist for the Center for the Study of Social Policy. His responsibilities were the studies in alternative futures, innovation diffusion, and social policy applications for clients including the Carter White House Extraterrestrial Communications Study, the National Science Foundation, U.S. Congress (Office of Technology Assessment), the U.S. Department of Energy, and the State of California (Energy Plan).

Later career

Webre was a member of the Governor's Emergency Taskforce on Earthquake Preparedness for the state of California between 1980 & 1982. Between 1982-1987, he was a Non Governmental Organization (NGO) Delegate at the United Nations in New York. He was involved with the Communications Coordination Committee for the United Nations, with the UNISPACE Outer Space Conference (Vienna) and involved with the United Nations Second Special Session on Disarmament. In 1983, Webre joined the New York State Legislative Institute as Senior Fellow. He spent time on issues of public policy studies and legislative initiatives for the New York State legislature as well as the development of Graduate School of Political Management. In 1986, he became President of Legal Access Worldwide (L.A.W.) an international legal access and litigation management firm. In 1987, Webre produced and hosted "The Instant of Cooperation", the first live radio broadcast between USA and the then Soviet Union, carried live by Gosteleradio and NPR satellite on WBAI-FM. In 1996, he was an elected delegate to the Texas Democratic Presidential Convention in Dallas, Texas.

In 2000, he was a presenter at the Presidential Forum on Off-Planet Cultures Policy at the Santa Clara Convention Center in California. Since 2002, he is the host of "The Monday Brown Bagger", a public affairs radio talk show on Coop Radio CFRO 102.7 FM in Vancouver, British Columbia. He is a founding director of Canada's No Weapons in Space Campaign (NOWIS) established in 2002. In 2004, he created the Campaign for Cooperation in Space (CCIS), an international organization where he works with others to prevent the weaponization of space and promote the transformation of the war economy into a peaceful, cooperative space exploration industry. On March 8, 2004, Webre attended the Council of Canadians public forum at the Maritime Labour Centre in Vancouver. On March 14, 2005 Webre joined the editorial and advisory team for Peace Media. On February 16, 2007, Webre said that the 2007 Chinese anti-satellite missile test occurred in order to stop the United States from proliferating weapons in space.

Institute for Cooperation in Space

Alfred Webre and Dr. Carol Rosin founded the Institute for Cooperation in Space (ICIS) in 2001. The ICIS mission is to educate decision-makers and the grassroots about why it is important to ban space weapons. Through the help of Congressman Dennis Kucinich, the Space Preservation Act (HR 3657) was introduced to the 108th Congress on January 23, 2002. ICIS continues to lobby for a Space Preservation Treaty conference where leaders of the world would gather to ban space weapons. Supported by former Canadian Defence Minister Paul Hellyer who believes that this treaty would help put a cap on the war industry and open the door for international cooperation in outer space exploration. Thus, transforming the "war based" economy into a "peace based" economy.

The ICIS board is made up of various prominent individuals such as former astronauts Edgar Mitchell and Dr. Brian O'Leary, and formerly the late Arthur C. Clarke, General Council Daniel Sheehan and John McConnell who is the founder of International Earth Day.. Alfred Webre resigned from the Board of Directors of ICIS on January 1, 2011 to focus on a treaty to ban HAARP, which he alleges to be a weapon.

Exopolitics

Webre believes that there is intelligent extraterrestrial life in our Universe. He is the author of the online e-book, "Towards a Decade of Contact (2000)" and the book ''Exopolitics: Politics, Government, and Law in the Universe'' (2005). The exopolitics model functionally maps the operation of politics, government and law in an intelligent Universe, and provides an operational bridge between models of terrestrial politics, government and law, and the larger models of politics, government and law in Universe society.

Webre believes that as exopolitics posits, the truest conception of our human circumstance may be that we are on an isolated planet in the midst of a populated, evolving, highly organized inter-planetary, inter-galactic, multi-dimensional Universe society. He believes that we live on a planet that has been quarantined (the Zoo Hypothesis) and that we are now being given an opportunity to join the rest of the spiritually evolved Universe Society in peace, thus an opportunity to avoid environmental global self-destruction or global self-destruction through war.

On March 10, 2007, Webre launched the Exopolitics Radio program, hosted by 1480 KPHX (which at the time was the Air America Radio affiliate, and Nova M Radio flagship station, in Phoenix) until the fall of 2008; the program remains in production and is distributed via podcast on its own website . Guests on the program have been generally advocates of views similar to that of Webre, and many are well known within the UFO research/enthusiast (and to a lesser extent the New Age) community.

Media

Books

''Exopolitics: Politics, Government, and Law in the Universe''. ISBN 978-0-9737663-0-1

''The Levesque Cases''. ISBN 978-0-9694459-0-6

''The Age of Cataclysm''. (co-author Phillip H. Liss). Berkeley Publishing (1974)

Videos

Safespace - Fastwalkers - Winter 2006

Star Dreams Initiative - Victoria, British Columbia, Canada - May 2006

Audio

Radio Shows

Exopolitics Radio - every Saturday at 11:00 p.m. (EST)

Exopolitics Radio

Radio Interviews

As You Wish - May 20, 2006

Binnall of America - Part 1 and Part 2 - December 17, 2005

Journeys With Rebecca - August 29, 2005

Jerry Pippin - April 23, 2005

Jerry Pippin - March 1, 2005

References

External links

Official links

Exopolitics - Homepage

Campaign for Cooperation in Space (CCIS) - Homepage

Alfred Webre's Official Facebook Account

Miscellaneous links

Hon. Paul Hellyer Supports a ban on space weapons

Washington, DC Exopolitics conference with CNN's former anchor Cheryll Jones as Co-Host

Category:1942 births Category:Living people Category:People from Pensacola, Florida Category:American environmentalists Category:American anti-war activists Category:American UFO writers Category:Washington, D.C. lawyers Category:Futurologists Category:SRI International people Category:Ufologists Category:UFO conspiracy theorists Category:Yale Law School alumni Category:Yale University faculty Category:Fulbright Scholars Category:Writers from Florida