China
Africa
Explore chapters and articles related to this topic
Solar Activity as a Danger to Ground-based Technological Systems
Published in Olga Sokolova, Nikolay Korovkin, Masashi Hayakawa, Geomagnetic Disturbances Impacts on Power Systems, 2021
Olga Sokolova, Nikolay Korovkin, Masashi Hayakawa
The main feature of the Sun's magnetic field is a cyclical change of its polarity with a period of 22 years which, in turn, is the cause of 11-year solar cycle. Solar cycle is the nearly periodical (11 years) change in the solar activity. The long-term behavior of the 11-year solar cycle variations and that of even higher periodicities (e.g., the Gleissberg cycle of ∼90 years) is highly important in terms of space climate [6]. The most common solar activity measures is the sunspot number. The sunspot is an area with reduced surface temperature which expends less energy. Sunspots can be resembled as a visible darker areas on the Sun's surface. Sunspots are magnetic in nature. Therefore, solar maximum and solar minimum refer to periods of maximum and minimum sunspot counts. Cycle spans from one minimum to the next.
Unsteady, Non-Linear, and Chaotic Systems
Published in L.M.B.C. Campos, Non-Linear Differential Equations and Dynamical Systems, 2019
The solar magnetic field changes polarity during a solar cycle of 11–14 years. The change of polarity or inversion of direction of the solar magnetic field implies that it is weak at the start and end of a cycle and is strongest in mid-cycle. The evolution of the solar magnetic field during the solar cycle is observed in sunspots that are dark regions of strong magnetic field in the photosphere. The number and size of sunspots and their motion change during the solar cycle from a maximum at mid cycle to a minimum at the start; the solar cycles are not identical with the observed Maunder minimum occurring in 1645–1715. Conversely, in periods of high solar activity the stronger magnetic field affects the whole, including the atmosphere up to the corona, leading to the observation of (i) solar flares that liberate large amounts of energy and hence strong radiation; and (ii) coronal mass ejections that lead to particle streams more intense than the average solar wind. Both (i) and (ii) can be a hazard to space travel or habitation outside the earth's atmosphere and ionosphere.
Climate Manifestations
Published in Gregory T. Haugan, The New Triple Constraints for Sustainable Projects, Programs, and Portfolios, 2016
Since man started inhabiting the Earth and developed curiosity, there has been interest in sunspots and solar flares. In 1843 Samuel Heinrich Schwabe, a German astronomer, discovered the existence of a regular solar cycle through a 17-year term of observations. The solar cycle is represented by the number of sunspots from year to year on the solar disk. Rudolf Wolf, a Swiss astronomer, carried out historical reconstruction back to the seventeenth century and established a numbering scheme for the cycles starting with the cycle of 1755-1766. The average duration of the cycles is just under 11 years, with some cycles as short as 9 years and others up to 14 years. We are now in Cycle 24, which started early in January 2008 when a reversed-polarity sunspot appeared. Figure 11.4 illustrates the sunspot cycles and the numbers of annual sunspots from about 1610 to the present.
A Comparative Study of non-deep Learning, Deep Learning, and Ensemble Learning Methods for Sunspot Number Prediction
Published in Applied Artificial Intelligence, 2022
Yuchen Dang, Ziqi Chen, Heng Li, Hai Shu
Additionally, five ensemble learning methods (via mean, median, the error-based method, linear regression, and XGBoost) are applied to the forecast results of non-deep learning models, deep learning models, and all base models, separately. Ensemble models based on deep learning models have more accurate predictions than those based on non-deep learning models or all base models. Our proposed XGBoost-DL model that uses XGBoost to ensemble the four deep learning models achieves the best performance among all base and ensemble models as well as NASA’s forecast. The outstanding result of our XGBoost-DL is owing to its strong two-level nonlinear ensemble architecture formed by decision trees built upon deep learning models. Our prediction indicates that Solar Cycles 25 and 26 will be overall stronger than the most recent Solar Cycle 24, and will have the peak sunspot number of 133.47 in May 2025 and 164.62 in November 2035, respectively, which are similar to but later than the peaks forecast by NASA at 137.7 in October 2024 and 161.2 in December 2034.
Applicability of sunspot activity on the climatic conditions of Gilgit-Baltistan region using fractal dimension rescaling method
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Ali Khan, Syed Muhammad Murshid Raza, Sajjad Ali
The sun is foremost source of energy giving away its radiation fluxes toward the atmosphere and surface of the earth. The radiated energy is not always constant due to sunspots cyclic activity. The sunspots have been reported since ancient times but explicitly recognized as physical features on the solar surface in the early 17th century. The number of sunspots has been carefully observed and recorded that the sun is not the unchanging body as traditionally assumed to be. The sunspots recorded during past 56 years show a cyclic behavior, conventionally that can be represented by sunspot number (SN), the group of sunspots have tendencies of growing as well as decaying on timescale of 9–13 years. On the average, this is known as the 11-year solar cycle, or simply the solar cycle. The recorded information of about past four centuries indicates that this behavior has been persistent over the entire period, but the cyclic amplitude is very variable. For instance, the period at the end of the 17th century sunspot numbers declined near to zero for some decades, this period is now known as Maunder Minimum, later researches of this cycle found a link with the Little Ice Age. Similarly, the low activity at the start of the 19th century is called the Dalton Minimum and the comparatively high activity observed over the recent past 50 years. This shows variations in the cyclic amplitude of the sunspot cycles.