相关论文: Long-term temporal variations in the areas of suns…

The combined Greenwich and Solar Optical Observing Network (SOON) sunspot group data during 1874-2013 are analyzed and studied the relatively long-term variations in the annual sums of the areas of sunspot groups in 0-10 deg, 10-20 deg, and…

Using Greenwich and SOON sunspot group data during the period 1874 -- 2005, we find that the sums of the areas of the sunspot groups in $0^\circ$ -- $10^\circ$ latitude-interval of the Sun's northern hemisphere and in the time-interval,…

Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles 2023 by using Rome (cycles 2021) and Learmonth Solar…

We analysed the combined Greenwich (1874-1976) and Solar Optical Observatories Network (1977-2011) data on sunspot groups. The daily rate of change of the area of a spot group is computed using the differences between the epochs of the spot…

Using the combined Greenwich (1874-1976) and Solar Optical Observatories Network (1977-2009) data on sunspot groups, we study the long-term variations in the mean daily rates of growth and decay of sunspot groups. We find that the minimum…

Relative variations in the number of sunspots and sunspot groups in activity cycles have been analyzed based on data from the Kislovodsk Mountain Astronomical Station and international indices. The following regularities have been…

The recent paucity of sunspots and the delay in the expected start of Solar Cycle 24 have drawn attention to the challenges involved in predicting solar activity. Traditional models of the solar cycle usually require information about the…

We have analysed the combined Greenwich and Solar Optical Observing Network (SOON) sunspot group data during the period of 1874-2011 and determined variations in the annual numbers (counts) of the small, large and big sunspot groups (these…

We find that the mean meridional motion of the spot groups varies considerably on a time scale of about 5-20 years. The maximum amplitude of the variation is about 10-15 m/s in both the Sun's northern and the southern hemispheres. Variation…

We investigate solar activity by focusing on double maxima in solar cycles and try to estimate the shape of the current solar cycle (Cycle 24) during its maximum. We analyzed data for Solar Cycle 24 by using Learmonth Solar Observatory…

Detailed models of the solar cycle require information about the starting time and rise time as well as the shape and amplitude of the cycle. However, none of these models includes a discussion of the variations in the length of the cycle,…

We analyze the temporal distribution of sunspot groups for even and odd cycles in the range SC12-SC24. It seems that cycle 24 is a characteristic even cycle, although with low amplitude. The number of large sunspot groups for cycle 24 is…

Recently, using Greenwich and Solar Optical Observing Network sunspot group data during the period 1874-2006, (Javaraiah, MNRAS, 377, L34, 2007: Paper I), has found that: (1) the sum of the areas of the sunspot groups in 0-10 deg latitude…

In this study, we used two methods to investigate the periodic behavior of sunspot counts in four categories for the time period January 1986-October 2013. These categories include the counts from simple (A and B), medium (C), large (D, E,…

We analysed the combined data of sunspot groups from Greenwich Photoheliographic Results (GPR) during the period 1874-1976 and Debrecen Photoheliographic Data (DPD) during 1977-2017 and determined the monthly mean, annual mean, and 13-month…

We studied the relation between the distribution of sunspot groups and the Gleissberg cycle. As the magnetic field is related to the area of the sunspot groups, we used area-weighted sunspot group data. On the one hand, we confirm the…

Using the Solar Optical Observing Network (SOON) sunspot-group data for the period 1985-2010, the variations in the annual mean equatorial-rotation rates of the sunspot groups are determined and compared with the known variations in the…

Data from three solar observatories, Learmonth, Holloman, and San Vito, are used to study the variations in the average number of sunspots per sunspot group. It is found that the different types of sunspot groups and the number of sunspots…

We investigate the size distribution of the maximum areas and the instantaneous distribution of areas of sunspot groups using the Greenwich sunspot group record spanning the interval 1874-1976. Both distributions are found to be well…

The Solar Cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots…