the Sun Spot Cycle
The Schwabe cycle, also known as the sun spot cycle, is a solar activity cycle that is thought to influence the Earth’s climate. While the exact mechanism of how the sun’s cycles work is still a mystery, there is a good chance that they are related to the evolution of complexes of solar activity. These complexes are said to involve meridional flow, which produce weaker polar fields. In addition, QBPs (Quasi-Bipolar Phases) are thought to be related to the evolution of these complexes.
Bipolar active regions tend to have the same leading polarity
In solar physics, bipolar active regions (BMRs) are small coronal holes that have two magnetic poles that are opposite in polarity. This type of ephemeral magnetic field is found in a few coronal holes, and is one of the major types of microflare events.
Several researchers have studied the emergence of bipolar active regions. They have compared the effects of several factors on the location and polarity of these active regions.
A key factor in this type of activity is the change in north-south separation of polarities. The number of polarities increases as the distance from the center increases. While the scatter in the magnitude of this separation increase with lower-flux regions, it remains relatively constant with high-flux regions.
Another factor that affects the position of polarities is the tilt angle. Polarities are separated by the latitudinal distance and the longitudinal distance. These factors are shown in the top panel and bottom panel, respectively.
As previously mentioned, a positive tilt angle occurs during solar cycle 24. This means that the leading polarity of an active region is closer to the equator than the following polarity. It is also a measure of the flux of the active region.
Observations show that the time between emergence and polarity reversal is approximately 14 hours. Simulators also suggest that emergence does not occur until about 14 hours prior to emergence. However, the observed emergence process is a 1-1.5 day long process.
In addition, the presence of a polarity center can be determined by shifting the search mask. This can be done by computing the center of the polarity using an algorithm.
The most common method of locating the center of the polarity is bilinear interpolation. Bilinear interpolation uses four of the nearest pixels of the map to locate the polarity. However, this method can introduce significant differences in the location of the polarity.
There are several other ways to estimate emergence locations. One method is by taking a feature recognition algorithm and calculating the centroid position of primary opposite polarities.
Meridional flow produces weaker polar fields
Meridional flow is a process that transports the poloidal magnetic field to the interior of the Sun. This poloidal magnetic field is then transported to the evolving photospheric convection cells. The resulting modified poloidal field is stretched in azimuthal direction by differential rotation. It then undergoes diffusion to the tachocline region.
In the process, part of the generated flux is advected by meridional flow circulation to the poles. The overall process delays the evolution of the polar magnetic field. However, short-term variations reduce the extent to which a representative polar field strength is achieved.
A new study by Karak (2010) provides evidence that reconstructed polar fields improve solar cycles reproduction. This study also highlights that meridional flow fluctuation is a fundamental ingredient of the simulation of solar activity.
The most prominent incompatibility is observed during the declining phase of the sunspot cycle. Although a large portion of the polar field strength is achieved during the rising phase, the magnitude of the corresponding polar field in the decline is significantly less.
This discrepancy in polar field strengths can be addressed by reconstructing the hemispheric polar field from a longer hemispheric sunspot area record. Alternatively, a single hemispheric cell approach can be used to reconstruct solar-like activity.
Two exogenous input series are proposed as inputs to the dynamo model: a regular sunspot area record and a reconstructed polar field. Both series contain sufficient information to reconstruct the polar fields from the start of the Schwabe cycles.
The corresponding time series are reconstructed using NARX modeling. The reconstructed polar field time series are then used to construct a poloidal potential modulation in the dynamo model. While the reconstructed polar field time series are not exactly accurate representations of a simulated polar field’s history, they are useful for providing clues to the possible past behavior.
Comparisons of the right tail of the reconstructed polar field curves to the observational PF data base reveal that the reconstructed polar field is more closely matched to the observables. Furthermore, the reconstructed polar field time series show an expected maximum value at the beginning of the simulated Schwabe cycle. These predictions are not yet sufficient to indicate the onset of a Grand Minimum.
QBPs may be related to the evolution of complexes of solar activity
The emergence of sunspots on the solar surface is part of a solar cycle. This cycle, in turn, is governed by a magnetic dynamo mechanism in the interior of the Sun. As the dynamo mechanism modulates, the resulting activity changes. These changes, in turn, impact the environment of the planetary atmospheres.
Observations of the Sun during the past few centuries have revealed a number of trends in the evolution of the sunspot cycle. Among these trends are: a reduction in overall solar radiation output when sunspots first appear, and a gradual increase in total solar radiative output when the sunspots decay.
These long-term fluctuations in the solar cycle may affect the space climate. The heliosphere is influenced by these fluctuations, and a wide range of effects are believed to be involved in causing them.
Long-term variations in the sun’s activity are a result of stochastic variation in the parameters of the dynamo mechanism. They can originate from a combination of factors, including time-delay dynamics and non-linear feedback mechanisms.
The Babcock-Leighton mechanism is one of the major processes that drive the variations in the solar cycle. This process is thought to have a large-scale component and is thought to be responsible for the formation and persistence of the grand minima phase of the solar cycle. It is believed that the a-effect is necessary to recover from the grand minima phase.
Recent modeling of long-term solar activity suggests that the weak mean-field a-effect is a crucial factor in recovering from the grand minima phase. But the model does not predict the exact timing and magnitude of the reconnection events.
There are also a variety of other physical mechanisms that drive the amplitude of the cycle. Turbulent pumping and meridional circulation are two prominent factors that affect the memory of the cycle. Nevertheless, the long-term cycle is quasi-periodic, making predictions difficult.
Physically inspired kinematic dynamo models are beginning to develop. However, full MHD, direct numerical simulations are still at an early stage and have yet to display the complex nature of the plasma flows in the stellar convection zones.
Long-term variations of solar magnetic field and climate variations are somehow interrelated
Long-term variations in the solar magnetic field and climate variations are somehow interrelated. Both are driven by feedbacks between ocean temperatures and wind patterns. But the influence of the sun’s magnetic field on global temperature change is minimal. It may be worth studying how the relationship between the two variables works.
The solar cycle consists of a series of 11-year rotations that are triggered by the sun’s magnetic field flipping. This process explains why the Sun’s brightness varies each year. And it might even affect weather.
A small community of scientists began studying the relationship between the two in the mid-19th century. They found that the amount of energy radiated by sunspots varies by about one part in 1,000 during the cycle.
As the sun’s activity increased, some regions saw warming. Others experienced cooling. Meanwhile, atmospheric carbon dioxide levels rose and fell in concert with the orbital wobbles. Eventually, Earth’s orbit would send the planet into another ice age.
During the Maunder minimum, the solar output was below average. It is believed that this period caused the Little Ice Age.
Another major effect of the solar magnetic cycle was a 22-year drought. This was attributed to severe droughts in the West. Nevertheless, it did not cause global warming.
A study in 1997 found that the global cloudiness increased when cosmic rays were higher. In response, researchers analyzed a huge bank of satellite observations and found that the amount of cosmic rays correlated with the solar cycle.
Studies of long-term variations in the sun spot cycle also found that the variations had a larger impact on climate than previously thought. However, their findings were too short to support any conclusions about long-term climate change.
To determine the sensitivity of the TSI to variations in the sun’s magnetic field, they extrapolated a composite TSI from measurements taken at 11 northern Hemisphere observatories. They found that a linear fit confirmed the validity of their extrapolation over 2.5 years.
Although the effects were weak, they were clearly seen in the atmosphere near the surface. That was not a surprise, since the surface of the Earth is influenced by the sun’s magnetic field.
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