相关论文: Long-term variation in distribution of sunspot gro…
In this paper we analyze the behavior of the daily Sunspot Number from the Sunspot Index Data Center (SIDC), the mean Magnetic Field strength from the National Solar Observatory/Kitt Peak (NSO/KP) and Total Solar Irradiance means from…
Independent of the normal solar cycle, a decrease in the sunspot magnetic field strength has been observed using the Zeeman-split 1564.8nm Fe I spectral line at the NSO Kitt Peak McMath-Pierce telescope. Corresponding changes in sunspot…
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 correlation between geomagnetic activity and the sunspot number in the 11-year solar cycle exhibits long-term variations due to the varying time lag between the sunspot-related and non-sunspot related geomagnetic activity, and the…
Empirical rules of solar cycle evolution form important observational constraints for the solar dynamo theory. This includes the Waldmeier rule relating the magnitude of a solar cycle to the length of its ascending phase, and the…
Sunspot engravings and measurements in 1660-1676 are analyzed to retrieve sunspot area and heliocoordinates. Based on these data, we revise the Hoyt and Schatten (The role of the sun in climate change, 1997) hypothesis of long-lived…
Research results from solar-dynamo models show the northern and southern hemispheres may evolve separately throughout the solar cycle. The observed phase lag between the hemispheres provides information regarding the strength of hemispheric…
We compare spectra of the zonal harmonics of the large-scale magnetic field of the Sun using observation results and solar dynamo models. The main solar activity cycle as recorded in these tracers is a much more complicated phenomenon than…
The solar northern and southern hemispheres exhibit differences between the intensities and time profiles of the activity cycles. The time variation of these properties has been studied in a previous article on the data of Cycles 12-23. The…
Although the Sun's polar magnetic fields are thought to provide important clues for understanding the 11-year sunspot cycle, including the observed variations of its amplitude and period, the current database of high-quality polar-field…
A new normalized sunspot-area series has been reconstructed from the series obtained by the Royal Greenwich Observatory and other contemporary institutions for the period 1874 - 2008 and the area series compiled by De la Rue, Stewart, and…
The frequencies of the solar acoustic oscillations vary over the activity cycle. The variations in other activity proxies are found to be well correlated with the variations in the acoustic frequencies. However, each proxy has a slightly…
Previous studies have shown that the variation over the solar magnetic activity cycle of the area of facular/network features identified on broad band and narrow band imagery is positively correlated with the sunspot area and number, the…
Rieger-type periodicity has been detected in different activity indices over many solar cycles. It was recently shown that the periodicity correlates with solar activity having a shorter period during stronger cycles. Solar activity level…
We have investigated the probability distributions of sunspot area and magnetic flux by using the data from Royal Greenwich Observatory and USAF/NOAA. We have constructed a sample of 2995 regions with maximum-development areas $\ge$ 500 MSH…
Polarity imbalance of the photospheric magnetic field was studied using synoptic maps of NSO Kitt Peak (1976-2016). Imbalance of positive and negative fluxes was considered for the fields with strength B>50 G in the sunspot zone (5 deg - 40…
Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations,…
Activity-related variations in the solar oscillation properties have been known for 30 years. However, the relative importance of the different contributions to the observed variations is not yet fully understood. Our goal is to estimate…
The spatial and temporal distributions of solar filaments were analyzed using data from the Meudon Observatory for the period 1919-2003 and the Kislovodsk Mountain Astronomical Station for the period 1979-2014. We scanned $H_\alpha$ solar…
The observed persistence of specific periodicities detected in time series associated with solar surface magnetic activity over several solar cycles has led to numerous papers supporting the existence of preferred longitudes. Recent…