相关论文: A Revised 27-day Recurrence Index

Solar activity is studied using a cluster analysis of the time-fluctuations of sunspot number. In the historic period (1850-1932) the cluster exponent was approximately equal to 0.37 (strong clustering) for the high activity components of…

Aims. The Sun shows strong variability in its magnetic activity, from Grand minima to Grand maxima, but the nature of the variability is not fully understood, mostly because of the insufficient length of the directly observed solar activity…

Measurements from the Mount Wilson Observatory (MWO) are used to study the long-term variations of sunspot field strengths from 1920 to 1958. Following a modified approach similar to that in Pevtsov et al. (2011), for each observing week we…

Transient and recurrent solar activity drive geomagnetic disturbances; these are quantified (amongst others) by DST, AE indices time-series. Transient disturbances are related to the Interplanetary Coronal Mass Ejections (ICMEs) while…

Comparison is carried out of the long term variation of the year averaged solar wind speed and interplanetary scintillation index with the variations of Wolf's numbers and A_P indexes of geomagnetic activity for the data of 20-24 solar…

We study the occurrence of magnetic storms in space age (1957-2021) using Dst and Dxt indices. We find 2526/2743 magnetic storms in the Dxt/Dst index, out of which 45% are weak, 40% moderate, 12% intense and 3% major storms. Occurrence of…

Sunspots are dark spots on the solar surface associated with strong magnetic fields. The number, area, and brightness of sunspots are supposed to reflect the intensity of the solar magnetic fields and are often used as proxies for their…

The correlation coefficients of the linear regression of six solar indices versus F10,7 were analyzed in solar cycles 21, 22 and 23. We also analyzed the interconnection between these indices and F10,7 with help of the approximation by the…

Complex network approaches have been recently developed as an alternative framework to study the statistical features of time-series data. We perform a visibility-graph analysis on both the daily and monthly sunspot series. Based on the…

Rotation is a significant characteristic of the Sun and other stars, and it plays an important role in understanding their dynamo actions and magnetic activities. In this study, the rotation of the solar chromospheric activity is…

Sunspots depict large variability during the last 100 years, a period called the Modern Maximum (MM). However, other variables are needed to study the long-term evolution, e.g., of weaker fields and different radiative emissions. Recently,…

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…

Solar variability occurs over a broad range of spatial and temporal scales, from the Sun's brightening over its lifetime to the fluctuations commonly associated with magnetic activity over minutes to years. The latter activity includes most…

The dynamic activity of the Sun, governed by its cycle of sunspots -- strongly magnetized regions that are observed on its surface -- modulate our solar system space environment creating space weather. Severe space weather leads to…

Long-term records of sunspot number and concentrations of cosmogenic radionuclides (10Be and 14C) on the Earth reveal the variation of the Sun's magnetic activity over hundreds and thousands of years. We identify several clear periods in…

Through meticulous daily observation of the Sun's large-scale magnetic field the Wilcox Solar Observatory (WSO) has catalogued two magnetic (Hale) cycles of solar activity. Those two (~22-year long) Hale cycles have yielded four…

The extension of the sunspot number series backward in time is of considerable interest for dynamo theory, solar, stellar, and climate research. We have used records of the Be-10 concentration in polar ice to reconstruct the average sunspot…

The total solar irradiance (TSI) varies on timescales of minute to centuries. On short timescales it varies due to the superposition of intensity fluctuations produced by turbulent convection and acoustic oscillations. On longer scale…

With the growing number of discovered exoplanets, the Gaia concept finds its second wind. The Gaia concept defines that the biosphere of an inhabited planet regulates a planetary climate through feedback loops such that the planet remains…

We show using superposed epoch analysis (SEA) that the most energetic protons (greater than 60 MeV) in near-Earth IMF have a peak almost immediately (less than a day) after peak in solar flare index (SFI), while protons greater than 10 MeV…