ترغب بنشر مسار تعليمي؟ اضغط هنا

A general method for the determination of duration of solar cycle maxima

55   0   0.0 ( 0 )
 نشر من قبل Stefano Sello
 تاريخ النشر 2013
  مجال البحث فيزياء
والبحث باللغة English
 تأليف Stefano Sello




اسأل ChatGPT حول البحث

The use of different solar activity indices like sunspot numbers, sunspot areas, flare index, magnetic fields, etc., allows us to investigate the time evolution of some specific features of the solar activity and the underlying dynamo mechanism. One of the problems when using these activity indices for some statistical analyses is the reliable determination of the maximum phases of different solar cycles which are generally characterized by a multi-peaked structure due to the presence of the so-called emph {Gnevyshev gap}. The main aim of this work is to propose a general method, without the introduction of ad hoc heuristic parameters, to determine the duration of a given solar cycle maximum phase through a long-term solar activity index like the Monthly Smoothed Sunspot Number (SSN). The resulting extended solar maxima allows us to include the multi-peaked structure of solar cycles and further the proposed method allows us to predict the solar maximum duration of the current solar cycle 24.


قيم البحث

اقرأ أيضاً

The onset of the Rush to the Poles of polar-crown prominences and their associated coronal emission is a harbinger of solar maximum. Altrock (Solar Phys. 216, 343, 2003) showed that the Rush was well-observed at 1.15 Ro in the Fe XIV corona at the Sa cramento Peak site of the National Solar Observatory prior to the maxima of Cycles 21 to 23. The data show that solar maximum in those cycles occurred when the center line of the Rush reached a critical latitude of 76 +- 2{deg}. Furthermore, in the previous three cycles solar maximum occurred when the highest number of Fe XIV emission features per day (averaged over 365 days and both hemispheres) first reached latitudes 20 +- 1.7{deg}. Cycle 24 displays an intermittent Rush that is only well-defined in the northern hemisphere. In 2009 an initial slope of 4.6{deg}/yr was found in the north, compared to an average of 9.4 +- 1.7 {deg}/yr in the previous cycles. An early fit to the Rush would have reached 76{deg} at 2014.6. However, in 2010 the slope increased to 7.5{deg}/yr (an increase did not occur in the previous three cycles). Extending that rate to 76 +- 2{deg} indicates that the solar maximum in the northern hemisphere already occurred at 2011.6 +- 0.3. In the southern hemisphere the Rush to the Poles, if it exists, is very poorly defined. A linear fit to several maxima would reach 76{deg} in the south at 2014.2. In 1999, persistent Fe XIV coronal emission known as the extended solar cycle appeared near 70{deg} in the north and began migrating towards the equator at a rate 40% slower than the previous two solar cycles. However, in 2009 and 2010 an acceleration occurred. Currently the greatest number of emission features is at 21{deg} in the North and 24{deg}in the South. This indicates that solar maximum is occurring now in the North but not yet in the South.
We propose a method to determine the galactic constants R_0 (distance to the Galactic Center) and V_0 (rotation velocity of the Sun) from measurements of distances, radial velocities and proper motions of objects near the solar circle. This is a modi fication of the solar-circle method to a more practical observational method. We apply the method to determine R_0 using data from the literature with known distances and radial velocities, and obtain R_0 = 7.54 +/- 0.77 kpc.
According to the scheme of action of the solar dynamo, the poloidal magnetic field can be considered a source of production of the toroidal magnetic field by the solar differential rotation. From the polar magnetic field proxies, it is natural to exp ect that solar Cycle 25 will be weak as recorded in sunspot data. We suggest that there are parameters of the zonal harmonics of the solar surface magnetic field, such as the magnitude of the $ell$=3 harmonic or the effective multipole index, that can be used as a reasonable addition to the polar magnetic field proxies. We discuss also some specific features of solar activity indices in Cycles 23 and 24.
The cyclic, enigmatic, and ubiquitous magnetism of the Sun provides the energy we need to survive and has the ability to destroy our technologically dependent civilization. Never before has understanding solar magnetism and forecasting its behavior b een so relevant. Indeed, on a broader canvas, understanding solar magnetism is a gateway to understanding the evolution and activity of other stars - the Sun is an astrophysical Rosetta Stone. Despite the centuries of observation, the past century of precise characterization, and significant advances in theoretical and numerical modeling over the past several decades, we have broken the cypher of the Suns global-scale magnetism. Using a host of observables spanning 140 years we will revisit an observational concept, the extended solar cycle, (ESC) that came to the fore in the mid-1980s but almost completely disappeared from the common consciousness of the global solar physics less than a sunspot cycle later - it is unclear why. Using a recently identified solar fiducial time, the end (or termination) of a solar cycle, we employ superposed epoch analysis to identify the ESC as a mapping of the Suns fundamental magnetic activity cycle and also as a recurring spatio-temporal unit of solar evolution. The ESC is a pattern from which the spatio-temporal pattern, and numerical modulation, of sunspots is produced. This effort illustrates that the ESC is the manifestation of the Suns Hale Cycle. We will close by pointing out areas of investigation indicated by the pattern of the Hale Cycle that may permit the conversion from observational correspondence to fundamental physical processes and a leap forward in understanding solar activity.
The paper presents results of a search for helioseismic events (sunquakes) produced by M-X class solar flares during Solar Cycle 24. The search is performed by analyzing photospheric Dopplergrams from Helioseismic Magnetic Imager (HMI). Among the tot al number of 500 M-X class flares, 94 helioseismic events were detected. Our analysis has shown that many strong sunquakes were produced by solar flares of low M class (M1-M5), while in some powerful X-class flares helioseismic waves were not observed or were weak. Our study also revealed that only several active regions were characterized by the most efficient generation of helioseismic waves during flares. We found that the sunquake power correlates with the maximum value of the soft X-ray flux time derivative better than with the X-ray class, indicating that the sunquake mechanism is associated with high-energy particles. We also show that the seismically active flares are more impulsive than the flares without helioseismic perturbations. We present a new catalog of helioseismic solar flares, which opens opportunities for performing statistical studies to better understand the physics of sunquakes as well as the flare energy release and transport.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا