The sun cycle or the solar magnetic activity cycle is an almost periodic 11-year change in solar activity (including changes in solar radiation and solar material expenditure) and appearance (changes in number and size sunspots, flares, and other manifestations).
They have been observed (by changes in the appearance of the sun and by visible changes on Earth, like the aurora) for centuries.
Changes in the Sun cause effects in space, in the atmosphere, and on the Earth's surface. While it is the dominant variable in solar activity, aperiodic fluctuations also occur.
Video Solar cycle
Definisi
The solar cycle has an average duration of about 11 years. Solar maximum and minimum solar respectively refer to the maximum period and minimum sunspot. The cycle lasts from one minimum to the next.
Maps Solar cycle
Observation history
The solar cycle was discovered in 1843 by Samuel Heinrich Schwabe, who after 17 years of observation saw a periodic variation in the average number of sunspots. Rudolf Wolf composed and studied these and other observations, reconstructing the cycle back to 1745, ultimately pushing this reconstruction into the early observation of sunspots by Galileo and his contemporaries in the early seventeenth century.
Following the Wolf numbering scheme, cycles 1755-1766 are traditionally numbered "1". Wolf creates the standard sunspot index index, the Wolf index, which continues to be used today.
The period between 1645 and 1715, when some sunspots, known as the Maunder minimum, after Edward Walter Maunder, who extensively examined this strange event, was first noted by Gustav SpÃÆ'¶rer.
In the second half of the nineteenth century Richard Carrington and SpÃÆ'¶rer independently recorded the phenomenon of sunspots that appeared at different latitudes in different parts of the cycle.
The physical basis of the cycle was explained by Hale and collaborators, who in 1908 showed that sunspots are very magnetic (the first detection of magnetic fields outside Earth). In 1919 they showed that the magnetic polarity of the sunspot couple:
- Always constant throughout the cycle;
- Being across the equator throughout the cycle;
- Reverses itself from one cycle to the next.
Hale's observations reveal that complete magnetic cycles include two solar cycles, or 22 years, before returning to their original state. However, since almost all of its manifestations are not sensitive to polarity, the "11-year solar cycle" remains the focus of research.
In 1961 the father-and-son team of Harold and Horace Babcock determined that the solar cycle is a spatiotemporal magnetic process that extends over the Sun as a whole. They observed that the sun's surface is magnetized outside the sun; that the magnetic field (the weaker) is the first order of the dipole; and that this dipole undergoes a polarity reversal with the same period as the sunspot cycle. The Horace Babcock model describes the Sun's oscillating magnetic field, with a quasi-stable periodicity of 22 years. This includes the exchange of oscillatory energy between the polo-magnetic and toroidal solar magnetic field materials. Two parts of the 22-year cycle are not identical, usually alternating cycles show higher (lower) sunspots (Gnevyshev-Ohl rule.)
History cycle
The number of Sunspots over 11,400 years has been reconstructed using Carbon-14-based dendroclimatology. The level of solar activity that began in the 1940s was remarkable - the last period of the same magnitude occurring about 9,000 years ago (during the warm Boreal period). The sun is at an equally high magnetic activity level of only ~ 10% of the last 11,400 years. Almost all of the previous high activity period is shorter than the current episode. The fossil record shows that the solar cycle has stabilized for at least the last 290 million years. For example, the length of the cycle during the initial Permian is estimated to be 10.6 years.
History of Grand minima solar activity came about 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 and 9170 BC. Since the observation began, the cycle has been around 9-14 years. Significant amplitude variations also occur.
It was first thought that 28 cycles had spanned 309 years between 1699 and 2008, giving an average length of 11.04 years, but recent research shows that the longest of these (1784-1799) seems to have actually been two cycles, meaning one of both must last less than 8 years.
Recent cycles
Cycle 25
There are many, often conflicting predictions, based on different methods, for a solar cycle of 25, ranging from very weak to moderate. Currently, no predictions can be made.
Cycle 24
The current solar cycle begins on January 4, 2008, with minimal activity until early 2010. It is on track to have the lowest recorded sunspot activity since accurate records began in 1750. This cycle featured the "highest peak" of the solar. The first peak reached 99 in 2011 and the second at the beginning of 2014 at 101. It seems that Cycle 24 will end in mid 2018.
Cycle 23
This cycle lasted 11.6 years, beginning in May 1996 and ending in January 2008. The maximum number of smoothed sunspots (monthly number of sunspots averaged over a twelve month period) observed during the solar cycle is 120.8 (March 2000), and the minimum is 1.7. A total of 805 days do not have sunspots during this cycle.
Phenomenon
Because the solar cycle reflects magnetic activity, various solar phenomena that are magnetically driven follow the solar cycle, including sunspots and coronal mass lesions.
Sunspots
The visible Sun surface, the photosphere, radiates more actively when there are more sunspots. Satellite monitoring of solar luminosity revealed a direct correlation between the Schwabe cycle and luminosity with peak-to-peak amplitude of about 0.1%. Luminosity is reduced by 0.3% on a 10-day time scale when large groups of sunspots rotate across Earth's view and increase by 0.05% to 6 months due to facula associated with large sunspot groups.
The current best information comes from SOHO (a joint project of the European Space Agency and NASA), such as the MDI magnetogram, in which the solar "surface" magnetic field can be seen.
When each cycle begins, the sunspots appear in mid-latitude, and then move closer and closer to the equator until it reaches the minimum of the sun. This pattern is best visualized in terms of so-called butterfly diagrams. The Sun image is divided into a latitudinal strip, and the average monthly fractional surface of the sunspots is calculated. It is vertically plotted as a color-coded bar, and the process is repeated month after month to generate this time series chart.
While the magnetic field changes are concentrated in the sunspots, the entire sun undergoes an analogue change, albeit smaller in magnitude.
Coronal mass ejection
The magnetic field of the sun forms a corona, giving its characteristic shape visible during a solar eclipse. The structure of a complex coronal magnetic field evolves in response to fluid motion on the surface of the sun, and the emergence of magnetic flux generated by the dynamo action in the solar interior. For reasons not yet understood in detail, sometimes these structures lose their stability, leading to the release of coronal masses into the interplanetary space, or flares, caused by the sudden release of magnetic energy that induce ultraviolet emission and X-ray radiation and energetic particles. The phenomenon of this eruption can have a significant impact on the upper Earth's atmosphere and space environment, and is a key driver of what is now called space weather.
The frequency of occurrence of coronal mass ejections and flares is strongly influenced by cycles. Flares of a given size are 50 times more frequent in maximum diesel than minimum. Massive coronal mass ejection occurs on average several times a day at maximum diesel fuel, dropping to one every few days at a minimum of diesel. The size of the event itself does not depend sensitively on the phase of the solar cycle. The case example is the three large X class flares that occurred in December 2006, very close to the sun minimum; an X9.0 flare on December 5 stood as one of the brightest in the record.
Pattern
The Waldmeier effect cites observations that cycles with larger maximum amplitudes tend to take less time to reach their maximums than cycles with smaller amplitudes; the maximum amplitudes are negatively correlated with the previous cycle length, helping predictions.
Solar maxima and minima also show fluctuations on a larger time scale than the solar cycle. The increase and decrease in trends may continue for a period of a century or more.
The 87-year cycle (70-100 years) Gleissberg , named after Wolfgang GleiÃÆ'Ÿberg, is considered a modulation of the Schwabe Cycle's amplitude, the Gleisberg Cycle implies that the next solar cycle has a maximum smoothed sunspot of about 145 Â ± 30 in the year 2010 (not 2010 only after the solar minimum cycle) and that the following cycles have a maximum of about 70 Â ± 30 by 2023.
The hundred-year-old variations related to magnetic fields in Corona and Heliosphere have been detected using Carbon-14 and cosmogenic cosmogenic beryllium-10 stored in terrestrial reservoirs such as ice sheets and tree rings and by historic observations of geomagnetic storm activity, which bridges the time gap. between the end of cosmogenic isotope data that can be used and the start of modern satellite data.
This variation has been successfully reproduced using a model that uses the magnetic flux continuity equation and observes the number of sunspots to measure the emergence of magnetic flux from the peaks of the sun's atmosphere and to the Heliosphere, suggesting that sunlight observations, geomagnetic activity and cosmogenic isotopes offer convergence. understanding of variations of solar activity.
The hypothesized cycle
Periodicity of solar activity with longer periods of the sunspot cycle has been proposed, including:
Cycles of 210 years (a.k.a. "de Vries cycle"). This cycle is recorded from radiocarbon studies, although "little evidence of the Suess Cycle" appears in a 400-year sunspot record.
The Hallstatt cycle is hypothesized to be extended for about 2,300 years.
An unnamed cycle can extend over 6,000 years.
In the carbon-14 cycle of 105, 131, 232, 385, 504, 805 and 2,241 years have been observed, the likelihood of a suitable cycle comes from another source. Damon and Sonett proposed medium- and short-term variations from the periods of 208 and 88 years; and suggests a 2300-year radiocarbon period that modulates the 208-year period.
During Permian Hulu 240 million years ago, the mineral layers formed in Castile Formation showed a 2,500-year cycle.
The solar magnetic field
The Sun's magnetic field forms the atmosphere and its outer layers along the corona and into the solar wind. Spatiotemporal variations cause a variety of measurable solar phenomena. Other solar phenomena are closely related to the cycle, which serves as a source of energy and dynamic engines for the first.
Effects
Solar
Surface magnet
Sunspots eventually rot, releasing the magnetic flux inside the photosphere. These fluxes are dispersed and stirred by the turbulent convection and large-scale flow of the sun. This transport mechanism leads to the accumulation of magnetic decay products in high latitudes, eventually reversing polarity of the polarity field (note how the blue and yellow fields are reversed in the Hathaway/NASA/MSFC graph above).
The dipolar component of the solar magnetic field reverses the polarity around the maximum time of the sun and reaches peak strength at the minimum of the sun.
Space
Spacecraft
CMEs (coronal mass ejections) produce high-energy proton radiation flux, sometimes known as cosmic rays of the sun. This can cause radiation damage to electronics and solar cells on satellites. Sun proton events can also cause a single event of cruel events (SEU) in electronics; at the same time, a decrease in the cosmic radiation of the galaxy during the maximum sun decreases the high energy component of the particle flux.
CME radiation is harmful to astronauts on space missions that are beyond the shield generated by the Earth's magnetic field. The design of future missions ( for example, , for Mars Missions) therefore incorporates a radiation-protected "storm shelter" for astronauts to retreat into during such events.
GleiÃÆ'Ÿberg developed a method of forecasting CME that relies on successive cycles.
On the positive side, increased radiation during the maximum solar expands the Earth's atmospheric envelope, causing debris of low orbiting spaces to reenter faster.
Galaxy cosmic ray flux
The expansion out of solar ejecta into interplanetary space provides efficient plasma overdensity in spreading high-energy cosmic rays entering the solar system from elsewhere in the galaxy. The frequency of solar eruption events is modulated by the cycle, altering the rate of scattering of cosmic rays outside the corresponding solar system. As a result, the cosmic ray flux in the inner solar system is anticorrelated to the overall level of solar activity. This anticorrelation is clearly detected in cosmic ray flux measurements on the Earth's surface.
Some of the high-energy cosmic rays that enter the earth's atmosphere collide pretty hard with the molecular atmosphere constituents to sometimes cause nuclear spission reactions. The fission products include radionuclides such as 14 C and 10 Be that settled on the surface of the Earth. Their concentration can be measured in ice cores, allowing reconstruction of the level of solar activity into the distant past. Such reconstructions show that the overall level of solar activity since the mid-twentieth century stands among the highest of the last 10,000 years, and that the times of repressed activity, of various times have occurred repeatedly over that span of time.
Atmosphere
Solar radiation
Total solar radiation (TSI) is the number of incidents of solar radiation energy in the upper atmosphere of the Earth. TSI variations were not detected until satellite observations began in late 1978. A series of radiometers were launched on satellites from the 1970s to 2000s. TSI measurements vary from 1360 to 1370 W/m 2 in ten satellites. One of the satellites, ACRIMSAT was launched by the ACRIM group. The controversial ACRIM gap between 1989-1991 between non-overlapping satellites was inserted by ACRIM composites showing an increase of 0.037%/decade. Another series based on ACRIM data is produced by the PMOD group. The series shows a downward trend of -0.008%/decade. This 0.045%/decade difference impacts on climate models.
Solar irradiance varies systematically during cycles, both in total radiation and in relative components (UV visible vs. and other frequencies). The solar luminosity is estimated to be 0.07 percent brighter during mid-day solar maximum than the minimum solar terminal. Photographic magnetism appears to be a major cause (96%) of TSI variations from 1996 to 2013. The ratio of ultraviolet to light appears to vary.
TSI varies in phase with a solar magnetic activity cycle with an amplitude of about 0.1% around an average value of about 1361.5 W/m 2 ("solar constant"). The average variation of up to -0.3% is due to large sunspot group and 0.05% by large facula and bright tissue on 7-10 day time scale (see TSI variation graph). The satellite-era TSI variation shows a small but detectable trend.
TSI is higher in maximum sun, although sunspots are darker (colder) than the average photosphere. This is due to the magnetic structure other than sunspots during the maximal sun, such as faculae and active elements of "bright" tissue, which is brighter (hotter) than the average photosphere. They collectively overcompensate for radiation deficits associated with cold sunspots, but lack much. The main driver of the TSI change on the sun's rotation time scale and the sunspot is the diverse photopheric coverage of this radially active magnetic sun structure.
The energy changes in UV radiation involved in the production and loss of ozone have atmospheric effects. The atmospheric pressure level of 30 HPa changes the height in phase with the solar activity during the 20-23 solar cycle. Increased UV radiation leads to higher ozone production, leading to stratospheric warming and polar displacement in the stratospheric and tropospheric wind systems.
Short term wavelength
With a temperature of 5870 K, the photosphere emits a proportion of radiation in extreme ultraviolet (EUV) and above. However, the upper layer of the sun's atmosphere (chromosphere and corona) radiates a shorter radiation-wavelength. Since the upper atmosphere is not homogeneous and contains significant magnetic structures, ultraviolet sun (UV), EUV and X-ray flux vary greatly in the cycle.
Montage photographs on the left illustrate this variation for soft X-rays, as observed by the Japanese satellite Yohkoh from after August 30, 1991, at the peak of cycles 22, to 6 September 2001, at the peak of cycle 23. Cycle related variations observed in UV solar flux or EUV radiation, as observed, for example, by SOHO or TRACE satellites.
Although it accounts for only a fraction of the total solar radiation, the impact of UV radiation, EUV, and solar X-ray in the upper atmosphere of the earth is enormous. Solar UV flux is a major driver of stratospheric chemistry, and increased ionizing radiation significantly affects ionospheric-induced temperature and electrical conductivity.
Solar radio flux
The emission from the Sun at centimetric wavelength (radio) is mainly due to coronal plasma trapped in the magnetic field above the active region. The F10.7 index is a measure of the solar radio flux per unit frequency at a wavelength of 10.7 cm, near the observed peak solar emission peak. F10.7 is often expressed in SFU or solar flux units (1 SFU = 10 -22 W m -2 Hz -1 ). This is a measure of diffuse, nonradiative, plasma corona heating. This is a very good indicator of the overall level of solar activity and correlates well with solar UV emissions.
Sunspot activity has a major influence on long distance radio communications, especially in shortwave waves although medium wave and low VHF frequencies are also affected. The high levels of sunspot activity leads to increased signal propagation in higher frequency bands, although they also increase the noise level of the sun and ionospheric disorders. This effect is caused by the impact of increased levels of solar radiation on the ionosphere.
10.7 cm of solar flux can interfere with point-to-point terrestrial communication.
Clouds
Cosmic rays changed during the cycle potentially have a significant atmospheric effect. Speculations about cosmic rays include:
- Changes in ionization affect the aerosol abundance that serves as a condensing core for cloud formation. During sun minima more cosmic rays reach the Earth, potentially creating ultra-small aerosol particles as precursors to Cloud's condensing core. Clouds form from a large number of condensing nuclei are brighter, longer life and tend to produce less rainfall.
- Changes in cosmic rays can cause an increase in certain cloud types, affecting Earth's albedo.
- It is proposed that, especially at high latitudes, cosmic ray variations may affect terrestrial lowland cloud layers (unlike the lack of correlation with high altitude clouds), which are partially influenced by interplanetary solar-driven magnetic fields (as well as parts through the upper galactic arm a longer period of time), but this hypothesis is not confirmed.
The paper then claims that the production of clouds through cosmic rays can not be explained by nucleation particles. Accelerator results fail to produce enough particles and large enough to produce cloud formation; this includes observations after a massive solar storm. Observations after Chernobyl showed no induced clouds.
Terrestrial
Organism
The impact of the solar cycle on living organisms has been investigated (see chronobiology). Some researchers claim to have found a connection with human health.
The amount of UVB ultraviolet light in the 300m that reaches Earth varies as much as 400% of the solar cycle due to the variation of the protective ozone layer. In the stratosphere, ozone is continuously regenerated by separating the molecules of O 2 by ultraviolet light. During minimum sunlight, the decreased ultraviolet rays received from the Sun cause a decrease in ozone concentration, allowing an increase in UVB to reach the Earth's surface.
Radio communication
Skywave mode radio communications operate by bending (biasing) radio waves (electromagnetic radiation) through the Ionosphere. During the "peak" of the solar cycle, the ionosphere becomes increasingly ionized by solar photons and cosmic rays. It affects the propagation of radio waves in complicated ways that can facilitate or impede communication. Skywave mode forecasting is very attractive for marine communications and commercial aircraft, amateur radio operators, and shortwave broadcasters. These users occupy frequencies in the High Frequency or 'HF' radio spectrum that are most affected by these solar and ionospheric variations. The change in solar output affects the maximum usable frequency, the highest frequency limit that can be used for communication.
Climate
Long-term and short-term variations in solar activity theorize to influence the global climate, but it has proven challenging to measure the relationship between solar and climate variations.
Initial research sought to correlate weather with limited success, followed by attempts to link solar activity with global temperatures. This cycle also affects the regional climate. Measurements from the Irradiation Monitor Spectral SORCE show that solar UV variability results in, for example, cooler winters in the US and Northern Europe and warmer winters in Canada and southern Europe during solar minima.
Three hypothetical mechanisms mediate climate impacts of solar variation:
- Total solar radiation ("Radiative forcing").
- Ultraviolet radiation. UV components vary more than the total, so if the UV for some reason (unknown) has a disproportionate effect, this may affect the climate.
- Sun-mediated wind galaxy cosmic ray changes, which can affect cloud cover.
The sunspot cycle variation of 0.1% has a small but detectable effect on Earth's climate. Camp and Tung showed that solar radiation correlated with variations of 0.18 Ã, Â ± 0.08Ã, K (0.32 Ã, Â ° F Ã, Â ± 0.14Ã, Â ° F) in measuring average global temperatures between the maximum sun and minimum.
The current scientific consensus, most specifically from the IPCC, is that solar variation plays a smaller role in encouraging global warming, as the size of recent solar variations is much smaller than the pressure from greenhouse gases. Also, solar activity in 2010 was not higher than in the 1950s (see above), while global warming has risen sharply. Otherwise, the level of understanding of the sun's impact on low weather.
Solar dynamo
The 11-year sunspot cycle is half of the twenty-year-old Babcock-Leighton solar cycle cycle, which corresponds to the exchange of oscillatory energy between the toroidal and the poloidal magnetic fields of the sun. In the maximum solar cycle, the external poloonal dipolar magnetic field is close to the minimum power of the dynamo-cycle, but the internal toroidal quadrupolar field, generated through differential rotation within the tachocline, is near its maximum strength. At this point in the dynamo cycle, the floating upwelling in the Convection zone forces the appearance of the toroidal magnetic field through the photosphere, resulting in pairs of sunspots, roughly aligned east-west with opposite magnetic polarities. The magnetic polarity of the sunspot pair alternates each solar cycle, a phenomenon known as the Hale cycle.
During the declining phase of the solar cycle, energy shifts from the internal toroidal magnetic field to an external polo field, and sunspots are reduced in number. At the minimum of the sun, the toroidal plane, thus, at minimum strength, the sun spots are relatively rare and the poloid plane is at its maximum strength. During the next cycle, the differential rotation converts the magnetic energy back from the poloid to the toroidal field, with polarity opposite to the previous cycle. The process continues, and in an idealized, simplified scenario, every 11-year sunspot cycle corresponds to a change in the polarity of the large-scale magnetic field of the Sun.
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