相关论文: An alternative measure of solar activity from deta…

Solar activity is an important driver of long-term climate trends and must be accounted for in climate models. Unfortunately, direct measurements of this quantity over long periods do not exist. The only observation related to solar…

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 record of solar activity is reviewed here with emphasis on peculiarities. Since sunspot positions tell us a lot more about the solar dynamo than the various global sunspot numbers, we first focus on the records of telescopic…

Our knowledge of the long-term evolution of solar activity and of its primary modulation, the 11-year cycle, largely depends on a single direct observational record: the visual sunspot counts that retrace the last 4 centuries, since the…

We have studied the relationship between three different versions of the sunspot number (Group, International and American sunspot number) and the number of active days (i.e., the number of days with spots on the solar disk). We have…

The method of active day fraction (ADF) was proposed recently to calibrate different solar observers to the standard observational conditions. The result of the calibration may depend on the overall level of solar activity during the…

The distribution of the sunspot group size (area) and its dependence on the level of solar activity is studied. It is shown that the fraction of small groups is not constant but decreases with the level of solar activity so that high solar…

The present paper reviews results derived from statistical studies on solar activity indices. The prolonged minimum phase of cycle 23 raised the question of peculiarities inherent in cycle 23. The most important solar activity index is the…

We have reconstructed the sunspot group count, not by comparisons with other reconstructions and correcting those where they were deemed to be deficient, but by a re-assessment of original sources. The resulting series is a pure solar index…

Sunspot numbers are important tracers of historical solar activity. They are important in the prediction of oncoming solar maximum, in the design of lifetimes of space assets, and in assessing the extent of solar-radiation impact on the…

Wavelet analysis of different solar activity indices, 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…

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…

On a centennial timescale, solar activity was quantified based on records of instrumental sunspot observations. This article briefly discusses several aspects of the recent archival investigations of historical sunspot records in the 17th…

Presented here is a review of present knowledge of the long-term behavior of solar activity on a multi-millennial timescale, as reconstructed using the indirect proxy method. The concept of solar activity is discussed along with an overview…

The Schwabe (~11 yr) value for the annual sunspot number is sometimes uncritically applied to other measures of solar activity, direct and indirect, including the 10.7 cm radio flux, the inflow of galactic cosmic rays, solar flare…

There exists a considerable amount of research claiming a puzzling anti-correlation between the neutrino detection rate at the Homestake experiment and indicators of solar activity such as the sunspot number, giving rise to explanations…

Solar magnetism is measured with different indexes: for instance the MPSI and the MWSI, number of sunspots, radio flux at 10.7 cm, Ca II K, Mg II K, EUV, He I or L_alpha. Bachmann & White (1994) had compared these indicators of the solar…

We summarize the fifty-year concerted effort to place the "activity" of the Sun in the context of the stars. As a working definition of solar activity in the context of stars, we adopt those globally-observable variations on time scales…

The paper shows the recurrence and cross recurrence plots of three time series, concerning data of the solar activity. The data are the sunspot number and the values of solar radio flux at 10.7 cm and of solar total irradiance, which are…

We study the visibility of sunspots and its influence on observed values of sunspot region parameters. We use Virtual Observatory tools provided by AstroGrid to analyse a sample of 6862 sunspot regions. By studying the distributions of…