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The paper presents the method for detecting exoplanets in the image archive obtained by telescopes of the MASTER Global Network since 2002. The unique archive represents homogeneous photometric data obtained over 20 years for the northern (MASTER-Amur, MASTER-Tunka, MASTER-Kislovodsk, M-ASTER-Tavrida, MASTER-IAC, MASTER-OAGH) and 11 years for the southern sky (MASTER-OAFA, MASTER-SAAO). Algorithm of gamma-ray burst error box observation on the MASTER wide-field telescopes make it possible to detect transit phenomena and find exoplanets in archival data. The article presents the results of a photometric analysis of the TESS exoplanet candidate TOI–3570.01. [ABSTRACT FROM AUTHOR]

The Wang–Shelley–Arge (WSA) solar wind (SW) model is based on the idea that weakly expanding coronal magnetic field tubes are associated with fast SW sources and vice versa. The Flux-Tube Expansion factor (FTE) is used to determine the degree of expansion of magnetic tubes. The FTE is calculated based on a model of the coronal magnetic field, usually in the potential approximation. The second input parameter of the WSA model is the distance from the base of the magnetic tube on the photosphere to the boundary of the corresponding coronal hole (Distance to the Coronal Hole Boundary, DCHB). These two parameters of the coronal magnetic field are related empirically to the speed of the solar wind near the Sun. The WSA model has shortcomings and does not fully explain the mechanisms of SW formation. This paper presents an analysis of the degree of correlation of various parameters of the magnetic field (length of field lines, latitude of the base of field lines, etc.) with the observed velocity SW. The parameters are calculated in potential (PFSS) and nonpotential approximations based on three synoptic series of magnetographic observations: the Kislovodsk Solar Telescope for Operative Predictions (STOP), SDO/HMI, and WSO. We found that the FTE correlates relatively weakly with solar wind speed, in contrast to field line lengths and DCHB. We propose an alternative relation to the WSA model that relates the length of field lines, the DCHB, and the amplitude of the magnetic field at the source surface with the velocity SW. The presented relationship is not based on the FTE and shows a better correlation with observations compared to the WSA model. We also optimized the formula in the WSA model for the STOP magnetograph. [ABSTRACT FROM AUTHOR]

This paper presents a procedure for reconstructing the longitudinal magnetic field from observational data of the complete profile of spectral magnetic lines. The method is based on a fast search algorithm for curve fitting for complete profiles of magnetically sensitive lines 6301.5 Å and 6302.5 Å. The magnetic field is calculated as the distance between the centers of the I-profiles of different polarization components. The centers are defined as the midpoints of the Gaussians approximating the I + V, I – V profiles. This approach makes it possible to carry out calculations rather quickly. The presented method makes it possible to reduce the noise in maps of a large-scale magnetic field and improve the accuracy of measurements, primarily of weak fields. The method has been tested to reconstruct the large-scale magnetic field from observations with the STOP full-disk magnetograph telescope (Kislovodsk) in 2014–2022. [ABSTRACT FROM AUTHOR]

The lifetime of individual solar pores and sunspots is analyzed according to the data of the HMI/SDO space observatory observations in the 24th and 25th activity cycles. It is found that the lifetime of individual sunspots and pores T differs from the Gnevyshev–Waldmeier rule formulated for groups of sunspots. For regular sunspots, that is, spots with nuclei, there is a linear dependence on the maximum area Smx: Tsp = –0.019(±0.2) + 0.027(±0.002)Smx. For solar pores, the dependence of the lifetime on the area has a logarithmic form Tpor = –0.24(±0.1) + 0.055(±0.014) log(Smx). Possible mechanisms of disintegration of spots and pores are studied. The lifetime for regular spots is probably related to convective currents. It has been established that the average velocity of the matter flow, determined from observations of Doppler velocities, increases with a decrease in the area of sunspots. This can accelerate the decay rate of sunspots with a decrease in the area of sunspots. For solar pores, the lifetime can be determined by the heating mechanism. [ABSTRACT FROM AUTHOR]

Based on the method of averaging the shape of sunspots identified in the HMI/SDO images in the 2010–2022 period, an analysis was made of the relative position of sunspot nuclei during their passage across the solar disk. To do this, in different ranges of sunspot areas, we constructed averaged boundaries of the photosphere-penumbra and the core-penumbra. We then tracked changes in sunspot shape at various distances from the center of the disk in the eastern and western hemispheres. A shift of the boundary of sunspot nuclei to the western edge of the sunspot has been observed. The relative value of the shift increases with the area of sunspots. We estimated the value of the Wilson depression for sunspots of various sizes. The magnitude of the depression varies from 100 km for small sunspots to 1000 km for large sunspots. There is some imbalance of the Wilson depression near the eastern and western boundaries of the core-penumbra, depending on the area of the sunspots and their latitude. [ABSTRACT FROM AUTHOR]

The possibilities for organizing a solar activity observation service for space weather forecasting are considered. At this stage, the most promising approach is the establishment of a ground-based observation network. This network should include solar magnetographs for observing large-scale magnetic fields of the Sun and patrol optical telescopes for detecting coronal mass ejections and solar flares. Magnetographic observations provide data for assessing recurrent solar wind streams. Patrol telescopes operating in continuous mode make it possible to detect eruptive moments and determine parameters of coronal mass ejections at the initial stage. The network can be complemented by other types of observations in radio and optical bands. The article discusses the composition of observation tools as well as methods and models of forecasting. [ABSTRACT FROM AUTHOR]

We consider variations of the azimuthal magnetic fields of the Sun in the 23 – 25 activity cycles according to observations with SDO/HMI, SOHO/MDI, and Kislovodsk/STOP telescopes. To identify azimuthal magnetic fields, the daily observations of LOS magnetic fields from the regions near the solar limb were analyzed. It is shown that with a sufficiently large averaging of the data, large-scale structures are distinguished, which can be interpreted by horizontal magnetic fields along the east – west direction. Azimuthal magnetic fields are visible at both low and high latitudes. Azimuthal fields at the same latitudes have opposite directions in the northern and southern hemispheres and also change sign in even and odd cycles of activity. The mechanism of formation of global azimuthal magnetic fields and their role in the cycle of solar activity is discussed. The near-surface azimuthal magnetic field is closely related to the activity cycle. Apparently, the azimuthal field is formed from U-shaped flux tubes of active regions (AR). Due to the presence of the tilt angle AR during differential rotation, the subsurface magnetic fields are pulled in the azimuthal direction. The role of azimuthal magnetic fields in solar activity cycles is considered. A scheme for the generation of a magnetic field different from Babcock – Leighton dynamo models is proposed. [ABSTRACT FROM AUTHOR]

The lifetime of individual sunspots and pores is analyzed according to Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) data from the period 2010 – 2022. It is found that the lifetime of individual sunspots and pores differs from the Gnevyshev–Waldmeier rule formulated for groups of sunspots. The dependence of the lifetime has a different pattern for different types of spots. For pores, the lifetime does not depend on the polarity of the magnetic field and has a logarithmic dependence on the area T pr = 0.24 (± 0.01) + 0.55 (± 0.14) log (S mx) . For regular sunspots with a developed penumbra, the dependence on the area has a linear form, but depends on the polarity of the magnetic field. For sunspots with a magnetic field of the leading polarity T ld sp = − 0.62 (± 0.2) + 0.036 (± 0.002) S mx . For sunspots of trailing polarity T tr sp = 0.95 (± 0.1) + 0.01 (± 0.001) S mx . The decay time and the total lifetime of sunspots is related to the rate of flow in sunspots. The average vertical speed in sunspots decreases with their increasing area. Moreover, the flow rate in the sunspots of the trailing polarity is higher than in the sunspots of the leading polarity. This difference in the velocity explains the difference in the lifetime of the sunspots of the leading and trailing magnetic polarity. [ABSTRACT FROM AUTHOR]

This paper analyzes the observations of an original spectroheliograph telescope installed at the Kislovodsk Mountain Astronomical Station of the GAO RAS. The telescope is intended for continuous observation of the activity of the solar chromosphere. The tool makes it possible to register the full profile of the H-alpha spectral line in each pixel of the solar disk with a frequency of approximately 1 minute. We analyzed observational data from September 2015 to July 2020 and found downdrafts with average velocities Vav is approximately 0.5 km/s. The flows are directed predominantly downwards with a small horizontal component. The properties of the streams do not significantly depend on the phase of the solar cycle, the area, or the relative brightness of active regions. We assume that these streams can influence the speed of the solar wind over active regions. [ABSTRACT FROM AUTHOR]

In this paper, we performed an analysis of the areas of sunspot groups of various classes according to the Zurich group classification. To do this, observations of sunspots at the Locarno Observatory (Locarno, Switzerland) for 21–24 activity cycles were digitized. In the Zurich classification of sunspot groups, there are classes from A to J. The classes correspond to the process of development and decay of sunspot groups. We combined the Locarno data with the measurements of the areas of sunspot groups performed at the Kislovodsk mountain astronomical station of the GAO RAS. Average areas were obtained for groups of different classes. In counting the number of sunspot groups, the contribution of groups of classes A and B, consisting of pores, is 34% and only 5.1% in the total area. It is shown that groups of classes A + B form a separate distribution of areas from groups of other classes. The areas separately of class A and class B, in turn, are also divided into two independent distributions. This indicates different physical mechanisms for the formation of pores and regular spots. The H + J unipolar sunspots make up ~19% of the total sunspot area, and the H and J classes can be described by a single distribution. [ABSTRACT FROM AUTHOR]

The article presents the results of the analysis of the geometric characteristics of sunspots for the period of 15 – 24 Cycles of activity according to the data of Kislovodsk (1956 – 2021) and Royal Greenwich (1918 – 1972) Observatories. To study the shape of sunspots, we used the method of obtaining the average density of the distribution, as well as the average values of the ratio of the extent of the sunspots in latitude and longitude. The deviation of the shape of sunspots from the axisymmetric configuration is investigated. It was found that the sunspots, as a rule, have an ellipsoidal shape and that the major axis of the ellipse, as a rule, is elongated along longitude and has a predominant slope to the equator, different in the northern and southern hemispheres. The relationship between the shape of sunspots in the current cycle and the amplitude of the next cycle of activity is found. The greater the elongation of the sunspots along the longitude in the current cycle, the more powerful the next cycle of activity will be. [ABSTRACT FROM AUTHOR]

A large number of small dark areas can be observed in the continuum with high-spatial resolution in recent satellite observations of the Sun, as well as in high-quality ground-based data. These regions have no penumbra, have a contrast of up to 20 % and are similar to solar pores. The characteristic area of such structures is from 0.3 to 5 μhm or from 0.5 to 7 Mm typical diameter. The number of such points in one image can be several hundred. The nature of such formations remains unclear. We have performed a selection of dark regions with a contrast of at least 3 % of the level of the quiet Sun using data obtained with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamcis Observatory (SDO) from 2010 to 2020. We have studied the properties of "dark dots", including their variation with the solar cycle, area distribution, and contrast. We also studied the intensity of the magnetic field of such structures. We found that the number of dark dots with an area of less than 5 μhm, in which the magnetic field is not significant and is less than | B | < 30 G, is from 60 to 80 % of the total number of structures of this size. This means that they are not associated with magnetic activity. The existence of such structures can significantly affect the calculations of the sunspot index since they can be mistaken with pores. [ABSTRACT FROM AUTHOR]

An analysis of the relative number of groups in cycles 21–24 based on the digitization of observations of sunspots at the Locarno Observatory (Locarno, Switzerland) was performed. In the Zurich classification of sunspot groups, there are classes from A to J. The classes correspond to the process of development and decay of sunspot groups. Class A and B groups correspond to single pores or small pore clusters (class A) and bipolar group (class B). For the reconstruction of solar indices, the relative number of groups (A + B) is of great importance. We found significant variations in the relative number of spot groups (A + B) in the activity cycles. If the relative number of groups (A + B) at the activity minima is 45–50%, then a decrease to 25–30% at the activity cycle maxima is observed. In the original spot index R, proposed by R. Wolf, pores were not considered, and many cores united by one penumbra were counted as one spot. After 1893, at the suggestion of A. Wolfer, the method of calculating the sunspot index changed. The pores and all individual cores in the spots began to be considered – this index is denoted by Rz. It is believed that between the spot indices of the Wolf (R) and Wolfer (Rz), there is a constant transition coefficient close to R/Rz = 0.6. We found that this assumption is incorrect, and R/Rz depends on the amplitude of the activity cycle, varying for the N19 cycle R19~ 0.34, and for the period of the grand minimum RMM ~ 0.64. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of a series of observations of the full H-alpha line profile in the solar chromosphere. The analysis is based on data from the spectroheliograph patrol telescope developed at the Kislovodsk Mountain Astronomical Station, which has been in operation since 2015. The telescope conducts continuous observations with a scanning time of the entire solar disk of about 1 min. The problem of measurement of the parameters of the H-alpha line with various methods of profile approximation is considered. The possibility of determining the Doppler shift in the H-alpha line with the use of a convolutional, artificial neural network has been studied. Also considered are the characteristic forms of the H-alpha profile in active regions of the Sun and the evolution of the line profile and Doppler velocities during the formation of a solar flare on the example of an X-class flare. [ABSTRACT FROM AUTHOR]

In this paper we studied long-term variations in the areas of coronal holes (CHs) reconstructed on the basis of synoptic Hα charts for the period 1887–2016 and occurrences of magnetic storms with gradual commencements. It was found that the temporal variations in mean yearly values of the CH areas in the northern and southern hemispheres are characterized by a pronounced ∼11-year periodicity, but they differ markedly on a multidecadal time scale. The wavelet spectra of the CH areas in the southern hemisphere, unlike those of the northern one, demonstrate persistent periodicities of ∼30–35 years, which are also observed in geomagnetic activity and climatic characteristics. The results of cross-wavelet analysis revealed a link between annual occurrences of magnetic storms with gradual commencements and variations in CH areas in both hemispheres. The obtained results allow us to conclude that the evolution of solar coronal holes may be considered as a possible factor of the formation of multidecadal cycles in geomagnetic activity, as well as climatic cycles. [ABSTRACT FROM AUTHOR]

There is a need today to recreate the Havana observational solar station because of the importance of obtaining a regular forecast of solar activity in a wide range of time intervals. The concept of the created observation network and the infrastructure of the monitoring station as a network element are described in detail. The functions of this network will provide continuous observational material for the Russian Sun and Space Weather Services and will be independent of space observations, but capable of using them for quality control. The physical foundations of complex observations for a wide range of heliogeophysical phenomena are considered. [ABSTRACT FROM AUTHOR]

The results of long-term mesoscale observations in the microwave range are reviewed. The rationale for the resumption of observations at the Havana Radio Astronomy Station is justified. Domestic observations at a wavelength of λ5 cm have a long observation interval and can effectively complement the global series of observations. A comparative analysis of the results of solar observation in the radio range and satellite observations in the UV and X-ray range is performed. The value of continuous observations for the assessment of space weather factors is shown. [ABSTRACT FROM AUTHOR]

Polar and low-latitude faculae were identified in daily images based on white-light observations from the MDI (1996–2011) and SOHO (2010–2019) space observatories. The boundaries of the faculae were combined with magnetic field observations at the closest possible instant of observation. The time and latitude distributions, as well as other properties of polar and low-latitude faculae, were analyzed. The resulting data on polar faculae were supplemented with observational data from Mitaka Observatory (Japan) for the period of 1951–1999. Thus, we compiled a summary series of polar activity for the period of 1951–2019. The distributions of polar faculae by area and magnetic field intensity are considered. The maximum distribution of the facula area at latitudes above θ > 55° occurs at values of approximately 6–10 mhs. The magnetic field of polar faculae has a maximum of B ~ 70–100 G. The amplitude of polar activity at the minimum in the 25th cycle approximately matches the amplitude in the 24th cycle. It can be expected that the amplitude of the sunspot activity cycle will be close to that of cycle 24. [ABSTRACT FROM AUTHOR]

Data from observations of the photospheric magnetic field at a number of ground stations (STOP, WSO, GONG) and by the SDO/HMI satellite for 2014–2019 are examined in terms of the accuracy of the model calculations of the speed of calm solar wind and the areas of coronal holes obtained on their basis. A high positive correlation was found (R > 0.5) between the simulation results and satellite observations (ACE, SDO/AIA193) for separate time periods. The best results in the modeling of the speed of the calm solar wind are given by the data from the ground stations WSO and STOP (Kislovodsk Mountain Astronomical Station, 2014). The temporal variability of the empirical coefficients of the model used in the forecasts was determined. [ABSTRACT FROM AUTHOR]

The paper presents machine-learning models for predicting powerful solar flares and background X-ray fluxes in the range of 1–8 Å. To predict solar flares for the next day, information was used on the current level of solar activity obtained from ground-based synoptic observations, such as characteristics of sunspots and radio fluxes at wavelengths of 10.7 and 5 cm, as well as the level of the background flux and the number of solar flares of the current day obtained from the GOES satellite. To predict the background fluxes of X-ray radiation, only data from ground-based telescopes were used. The high efficiency of the forecast for the next day is shown. The neural network was trained on data available since 2002. [ABSTRACT FROM AUTHOR]

The solar activity at different latitudes is analyzed based on daily observations at Kodaikanal, Mount Wilson, Sacramento Peak, and Meudon observatories in the CaIIK line. Activity elements of various sizes, from the elements of the chromospheric network to the flocculi, are identified. A joint database of observation results that provides information on solar activity for 1905–2018 is created. Bright elements at middle and high latitudes are distinguished in the CaIIK line in daily images, in addition to the low-latitude activity that accompanies the appearance of sunspots. The activity can be represented as a single process that begins at high latitudes during the decline phase of the previous solar cycle and continues at low latitudes as sunspot activity. The activity-drift pattern is studied for Cycles 14–24. It is more consistent with the hypothesis of an extended solar cycle than the concept of two activity waves from the midlatitudes to poles and equator obtained from the processing of faculae in white light. [ABSTRACT FROM AUTHOR]

A comparative analysis of the drift velocity of high-latitude prominences to the poles in solar cycles 13–24 is carried out. Data on the positions of prominences on weather maps from Wolfer (1887–1899) and (1904–1915) are used for the analysis. The data from digitized photographic plates with solar prominences obtained in the CaIIK line of the Kodaikanal Solar Observatory (India) for 1907–1956 are also used. These data are supplemented with daily observations of the prominences at Kislovodsk Mountain Astronomical Station (1957–2018). The dependence of the drift velocity of polar-crown prominences on the solar cycle strength is different for the northern and southern hemispheres. The drift velocity tends to decrease with increasing solar activity. This may be due to the fact that a strong large-scale magnetic field is observed at high latitudes before strong solar cycles. Its displacement rate, which is traced by the drift of polar prominences, then slows with the development of a cycle with an increasing polar field. [ABSTRACT FROM AUTHOR]

A comparative analysis of sunspot sizes in sunspot groups was performed. For this analysis, we used the database of characteristics of individual sunspots and pores according to observations at the Kislovodsk Mountain Astronomical Station (KMAS) and the photoheliographic data from the Debrecen Heliographical Observatory, Hungary (DPD). We found agreement in the full area index for sunspot groups. However, in the DPD data for 1974–2018, the number of groups is ~50% higher than that for the KMAS data. The difference is that there are a large number of groups in the DPD data with an area of 1 mdp or less. We also found a significant difference in the properties of spots and pores of different types within the group. A significant difference in the distribution pattern of the sunspot area, which is the largest in the group Smax and other spots Snomax, was detected. There are two local maxima, ~ 8–10 mdp and ~ 130–180 mdp, in the area distribution of the largest sunspot Smax in the group. The first maximum is associated with the existence of pores and transition spots in which the penumbra is at the formation stage. The second maximum Smax in the distribution is associated with the existence of regular spots. For the remaining spots Snomax in the group, the area distribution function monotonically decreases with increasing area. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents a study of the evolution of the photospheric magnetic field of active regions (ARs) of the Sun in which flares (larger than the M9 class in the Geostationary Operational Environmental Satellite (GOES) X-ray classification) occurred in 2010-2017. The purpose of this paper is to detect the precursors of flares. Thirteen ARs at a distance of not more than 45 degrees from the central meridian are selected for analysis out of 31 ARs in which flares larger than M9.0 were detected in the specified period. The magnetographic characteristics of the selected ARs are studied based on the Solar Dynamics Observatory (SDO) data. A flare index is proposed. It is calculated from the data of the Helioseismic and Magnetic Imager of SDO (SDO/HMI) and reflects the distance between regions of opposite magnetic polarity computed between the field boundaries by the threshold value. The analysis showed that a sharp increase in the flare index is detected in all the studied ARs 2-3 days before large flares. Flares larger than the M9.0 class occurred 5-20 h after the global or local maximum of the flare index. It is shown using the example of individual events that regions of the opposite polarity first converged and then relatively quickly separated from each other before large flares. The revealed features of evolution of ARs before large flares can be used to develop methods for predicting them. [ABSTRACT FROM AUTHOR]

Abstract: The properties of solar bipoles based on data from magnetic field observations at Mount Wilson Observatory during the period of 1917-2016 are considered. Special attention is given to variations in the size of the bipole magnetic axis during the solar cycle. It is shown that the distribution of the length of the bipole magnetic axis is close to lognormal with the exception of secondary local peaks. Secondary peaks are also present in the distribution of the tilt angles of bipoles at different latitudes. The influence of matter flows in supergranules on the length of the magnetic axis and the tilt angles of sunspot bipoles is discussed. [ABSTRACT FROM AUTHOR]

Abstract: The results of the digitalization of the centennial series of solar activity are considered. The data contain information on sunspots since 1918, sunspot umbra since 1917, plages since 1907, and spectral corona since 1939. In particular the digitalization of prominences from the observations in the Ca II K line in 1910-1954 and solar filaments from the observations in the H-alpha line in 1912-2002 acquired at the Kodaikanal Observatory are described. The methods of constructing composite maps of solar activity and presenting the resulting data series on the Internet are described. The long-term variations in solar activity are analyzed. [ABSTRACT FROM AUTHOR]

We present a model for the propagation of coronal mass ejections (CMEs) based on the interaction of CMEs with the solar wind through aerodynamic drag. The parameters of the solar wind are calculated based on observational data of the STOP magnetograph. The CME parameters, namely, the velocity vector and the estimated density at the initial stage of propagation, can be determined from the data of patrol telescopes. In the model, we consider a CME in the form of a cloud, represented by a set of points, and we track the trajectory of the motion of each point in the heliosphere. The simulation data can be used to estimate the geoefficiency of coronal mass ejections. [ABSTRACT FROM AUTHOR]

This paper continues the cycle of authors’ works on the detection of precursors of large flares (M5 and higher classes) in active regions (ARs) of the Sun by their microwave radiation and magnetographic characteristics. Generalization of the detected precursors of strong flares can be used to develop methods for their prediction. This paper presents an analysis of the development of NOAA AR 12242, in which an X1.8 flare occurred on December 20, 2014. The analysis is based on regular multiazimuth and multiwavelength observations with the RATAN-600 radio telescope in the range 1.65-10 cm with intensity and circular polarization analysis and data from the Solar Dynamics Observatory (SDO). It was found that a new component appeared in the AR microwave radiation two days before the X-flare. It became dominant in the AR the day before the flare and significantly decreased after the flare. The use of multiazimuth observations from RATAN-600 and observations at 1.76 cm from the Nobeyama Radioheliograph made it possible to identify the radio source that appeared before the X-flare with the site of the closest convergence of opposite polarity fields near the neutral line in the AR. It was established that the X-flare occurred 20 h after the total gradient of the magnetic field of the entire region calculated from SDO/HMI data reached its maximum value. Analysis of the evolution of the microwave source that appeared before the X-flare in AR 12242 and comparison of its parameters with the parameters of other components of the AR microwave radiation showed that the new source can be classified as neutral line associated sources (NLSs), which were repeatedly detected by the RATAN-600 and other radio telescopes 1-3 days before the large flares. [ABSTRACT FROM AUTHOR]

We consider the prospects for developing a forecast system for space weather (SPW) parameters with the use of home facilities for groundbased observations of solar activity. The space weather forecast can be conventionally divided into three components: (i) the prediction of recurrent, slowly changing events connected with the topology of the large-scale magnetic field, (ii) the estimation of fluxes of UV and high-energy radiation, and (iii) the observation of high-speed phenomena, such as solar flares and eruption processes, and the prediction of their consequences at the the Earth's orbit. At present, to predict recurrent events, data from regular observations of the large-scale field of the Sun by the solar telescope-magnetographs for operative (realtime) prediction (STOP) are effectively used. To estimate high-energy fluxes, to register eruption events, and to estimate their geoefficiency, data from the patrol optical telescope-spectrographs may be used. Patrol telescopes operate in automatic mode and register the processes with an interval of approximately one minute. To detect eruption processes, we propose a method based on the difference between the intensity values in the wings of chromospheric spectral lines. The results of the use of the observational complex of the Kislovodsk Mountain Astronomical Station for the SW forecast are considered in the paper. [ABSTRACT FROM AUTHOR]

The preliminary results of solar filaments distinguished in daily H-alpha observations at Kodaikanal (1912-2002) are presented. To mark the boundaries of solar filaments, methods based on automated procedures of marking low-contrast objects on the solar disk, as well as editing of the marked boundaries in a semiautomated manner, were developed. The characteristics of solar filaments were analyzed. Latitudinal diagrams of filaments number in 15-23 activity cycles were constructed. As is shown, one maximum in the filament latitudinal distribution may be clearly distinguished during activity cycles in both hemispheres. This maximum is located slightly higher (θ ~ 25°-30°) than the sunspot distribution maximum (θ ~ 14°-17°). However, there are no other local maxima related to the zonal structure of the large-scale magnetic field (Makarov and Sivaraman, 1989). [ABSTRACT FROM AUTHOR]

The results of the work of the global observation network are considered, and a comparative analysis of the data of various coronal observatories is performed. The coronal activity index has been reconstructed for the period 1939-2016 based on the data of various observatories in Kislovodsk system. For this purpose, the corona daily intensity maps from the Sacramento Peak and Lomnický Štít observatories according to the Solar-Geophysical Data journal have been digitized; they supplement the data of other observatories. The homogeneity and continuity of the corona observations at the Kislovodsk station, including activity cycle 24, is confirmed. Unfortunately, the only observatory at present that continues observation of the spectral corona in Fe XIV 5303 Å and Fe XIV 6374 Å lines is the Kislovodsk astronomical station Mountain Astronomical Station (MAS) of the Central Astronomical Observatory, Russian Academy of Sciences (Pulkovo). The data on the combined corona in 5303 Å line are analyzed. It is shown that there is a high correlation of the intensity index of green corona with solar radiation measurements in the vacuum UV region. Data on the beginning of the new 25th activity cycle in the corona at high latitudes are presented. [ABSTRACT FROM AUTHOR]

We used an automatic image-processing method to detect solar-activity features observed in white light at the Kislovodsk Solar Station. This technique was applied to automatically or semi-automatically detect sunspots and active regions. The results of this automated recognition were verified with statistical data available from other observatories and revealed a high detection accuracy. We also provide parameters of sunspot areas, of the umbra, and of faculae as observed in Solar Cycle 23 as well as the magnetic flux of these active elements, calculated at the Kislovodsk Solar Station, together with white-light images and magnetograms from the Michaelson Doppler Imager onboard the Solar and Heliospheric Observatory (SOHO/MDI). The ratio of umbral and total sunspot areas during Solar Cycle 23 is ≈ 0.19. The area of sunspots of the leading polarity was approximately 2.5 times the area of sunspots of the trailing polarity. [ABSTRACT FROM AUTHOR]

We applied automatic identification of sunspot umbrae and penumbrae to daily observations from the Helioseismic Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) to study their magnetic flux density ( B) and area ( A). The results confirm an already known logarithmic relationship between the area of sunspots and their maximum flux density. In addition, we find that the relation between average magnetic flux density ( $B_{\rm avg}$ ) and sunspot area shows a bimodal distribution: for small sunspots and pores ( A≤20 millionth of solar hemisphere, MSH), $B_{\rm avg} \approx 800~\mbox{G}$ (gauss), and for large sunspots ( A≥100 MSH), $B_{\rm avg}$ is about 600 G. For intermediate sunspots, average flux density linearly decreases from about 800 G to 600 G. A similar bimodal distribution was found in several other integral parameters of sunspots. We show that this bimodality can be related to different stages of sunspot penumbra formation and can be explained by the difference in average inclination of magnetic fields at the periphery of small and large sunspots. [ABSTRACT FROM AUTHOR]

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 established: (1) The relative fraction of small sunspots decreases linearly and that of large sunspots increase with increasing activity cycle amplitude. (2) The variation in the average number of sunspots in one group has a trend, and this number decreased from ∼12 in cycle 19 to ∼7.5 in cycle 24. (3) The ratio of the sunspot index (Ri) to the sunspot group number index ( Ggr) varies with a period of about 100 years. (4) An analysis of the sunspot group number index ( Ggr) from 1610 indicates that the Gnevyshev-Ohl rule reverses at the minimums of secular activity cycles. (5) Ratio of the total area to area of Ssp/Sum nuclei has long-term variation with a period approximately 8 cycles. Minimum ratio falls on 16–17 cycles of activity. (6) It has been indicated that the magnetic field intensity and sunspot area in the current cycle are related to the amplitude of the next activity cycle. [ABSTRACT FROM AUTHOR]

This paper considers the indices characterizing the minimum activity epoch, according to the data of large-scale magnetic fields and polar activity. Such indices include: dipole–octopole index, area and average latitude of the field with dominant polarity in each hemisphere, polar activity seen in polar faculae and Ca ii K line bright points, coronal emission line intensity (5303 Å) and others. We studied the correlation between these indices and the amplitude of the following sunspot cycle, and the relation between the duration of the cycle of large-scale magnetic fields and the duration of the sunspot cycle. The obtained relationships allow us to presume that the polar field is formed from the sources of both preceding and the current activity cycles during the decay phase and at the activity minimum. The balance in these sources would therefore determine the features of the following sunspot cycle. The prediction for the 24th activity cycle using these results leads to W=102±13. [ABSTRACT FROM AUTHOR]

The parameter G, which is determined from the general number of sunspots groups N g according to the daily observations G=∑(1/ N g)2, is offered. This parameter is calculated for the days when there is at least one sunspots group. It characterizes the minimum epoch solar activity. Parameter G mounts to the maximum during the epoch close to the minimal activity of sunspots. According to the data of the sequence of sunspots group in Greenwich–USAF/NOAA observatory format, observation data of Kislovodsk solar station and also daily Wolf number, the changes of parameter G during 100 years were reconstructed. It is demonstrated in the paper that parameter G’s amplitude in minimal solar activity n is linked with the sunspot cycle’s amplitude W n+1 or one and half cycles. The 24th activity cycle prediction is calculated, which makes W24=135(±12). [ABSTRACT FROM AUTHOR]

We continued a study of the long-term variations of temperature in the solar corona at all latitudes (Makarov, Tlatov, and Callebaut, 2002a). The series of the green (Fe xiv 530.3 nm; KI5303) and red (Fe x 637.4 nm; KI6374) coronal intensities for 1957–2002 has been obtained using the coronal observations at the Kislovodsk Solar Station. The mean monthly coronal intensities have been calculated at all latitudes (0–90˚) and in the high latitude (45–90˚) zones. It was found that the value of KI6374/KI5303increased about 2.0 times at the high latitudes during the last 45 years. This corresponds to a decrease of the average temperature by 0.1 ×106K of the polar corona. We suppose that a polar decrease of coronal temperature is connected with an increase of the area of polar zones A PZoccupied by unipolar magnetic fields (Makarov et al., 2002) and, probably, with an increase of the area of polar coronal holes. The maximum ratio KI6374/KI5303is observed during the minimum sunspot activity. [ABSTRACT FROM AUTHOR]

Occultation observations of the intensity of the FeXIV 530.3 nm and FeX 637.4 nm forbidden lines detected at the Kislovodsk Mountain Station during 1957–2002, indicate long-term changes in the structure of the solar corona. The monthly average intensities of green (KI530.3) and red (KI637.4) spectral lines are calculated for all latitudes (0°–90°) and for a high-latitude zone (45°–90°). A strong correlation (r = 0.91) between the green KI530.3 line intensity and the Wolf numbers is found and used to fill gaps in the observations. The ratio KI637.4/KI530.3 takes on its maximum value at the solar minimum. The KIp637.4/KIp530.3 ratio in the high-latitude solar zone (45°–90°) increased by more than a factor of two during 1957–2002. This means that the fraction of cool regions in the polar corona has more than doubled over these years. We suggest that this increase in the number of cool regions is related to an increase in the area of the polar solar zones occupied by magnetic field of a single polarity at the solar minimum, and possibly to an increase in the area occupied by polar coronal holes. This is associated with long-term variations in the internal structure of the Sun.© 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

We discuss long-time changes of polar activity of the Sun using the new observational data sets in the optical range during 1872-2001. A study of the secular and cycle variations of the magnetic activity at the high-latitude regions is the main goal that includes polar magnetic field reversals during 1872-2001 and secular changes of the duration of polar activity cycles. The secular increase of the area of polar zones during the minimum activity in the last 120 years and as consequence a decrease of coronal temperature of the Sun in the high-latitude zones during the last 50 years. Correlation between the polar cycles of Caii-K bright points with the Wolf sunspot numbers cycles, W(t), and the 22-year polar magnetic cycles of Caii-K bright points at the high latitudes during 1905-1995 is discussed. [ABSTRACT FROM AUTHOR]

Absorption areas have been studied in the line He i 10 830 Å, where active regions are seen as dark areas. The initial data were the synoptic maps for 1975–2002, as well as daily images 1992–2002 from the National Solar Observatory, represented as fits files. Areas were identified of objects having common boundaries, inside which the intensity of each pixel was less than a threshold value. Properties of the measured areas were studied and distributions were established. The maximum of the small structure (size less 50′′) distribution at low latitudes takes place during minimum activity. The distribution of small features drifts from the middle latitude to poles in the period from the beginning of the activity of the cycle up to magnetic field reversal of the poles and from the pole to the equator after the reversal. For large structures the distribution reflects the activity of sunspots. Filaments drift to the poles in the epoch of magnetic reversal. [ABSTRACT FROM AUTHOR]

We have defined the duration of polar magnetic activity as the time interval between two successive polar reversals. The epochs of the polarity reversals of the magnetic field at the poles of the Sun have been determined (1) by the time of the final disappearance of the polar crown filaments and (2) by the time between the two neighbouring reversals of the magnetic dipole configuration (l=1) from the Hα synoptic charts covering the period 1870–2001. It is shown that the reversals for the magnetic dipole configuration (l=1) occur on an average 3.3±0.5 years after the sunspot minimum according to the Hα synoptic charts (Table I) and the Stanford magnetograms (Table III). If we set the time of the final disappearance of the polar crown filaments (determined from the latitude migration of filaments) as the criterion for deciding the epoch of the polarity reversal of the polar fields, then the reversal occurs on an average 5.8±0.6 years from sunspot minimum (last column of Table I). We consider this as the most reliable diagnostic for fixing the epoch of reversals, as the final disappearance of the polar crown filaments can be observed without ambiguity. We show that shorter the duration of the polar activity cycle (i.e., the shorter the duration between two neighbouring reversals), the more intense is the next sunspot cycle. We also notice that the duration of polar activity is always more in even solar cycles than in odd cycles whereas the maximum Wolf numbers W\max is always higher for odd solar cycles than for even cycles. Furthermore, we assume there is a secular change in the duration of the polar cycle. It has decreased by ∼ 1.2 times during the last 120 years. [ABSTRACT FROM AUTHOR]

We study the rotation of the sector structure of the solar magnetic field by using Stanford magnetographic observations from 1975 until 2000 and magnetic synoptic Hα-maps obtained from 1904 until 2000. The two independent series of observations yielded the same rotation periods of the two-sector (26.86 days) and four-sector (13.64 days) structures. We introduce a new index of the solar rotation, SSPM(t). The spectral power density of the sector structure of the magnetic field is shown to exhibit a 22-year cyclicity. The two- and four-sector structures of the magnetic field rotate faster at the maxima of even 11-year sunspot cycles. This phenomenon may be called the Gnevyshev-Ohl rule for the solar rotation. The 11-year sector-structure activity cycles are shown to lead the 11-year sunspot cycles (Wolf numbers) by 5.5 years. A 55-year component with the slowest rotation in the 18th cycle (1945-1955) was distinguished in the sector-structure rotation. [ABSTRACT FROM AUTHOR]

The latitudes of the zonal boundaries of the global magnetic field of the Sun are determined from the magnetic neutral lines on synoptic Hα maps obtained during 1878–1999. The area of the polar zone occupied by magnetic field of a single polarity at solar minima has doubled over the last 120 years. This provides an explanation for the secular increase in heliospheric characteristics, which differs from the two-fold increase of the magnetic field strength predicted for this period. The temporal variations of the magnetic flux from the polar regions and their role in global changes of the Earth’s climate are discussed in connection with secular variations in the structure of the internal magnetic field of the Sun. © 2001 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Magnetic Hα synoptic maps of the Sun for 1915–1999 are analyzed and the intensities of spherical harmonics of the large-scale solar magnetic field computed. The possibility of using these Hα maps as a database for investigations of long-term variations of solar activity is demonstrated. As an example, the magnetic-field polarity distribution for the Hα maps and the analogous polarity distribution for the magnetographic maps of the Stanford observatory for 1975–1999 are compared. An activity index A(t ) is introduced for the large-scale magnetic field, which is the sum of the magnetic-moment intensities for the dipole and octupole components. The 11-year cycle of the large-scale solar magnetic field leads the 11-year sunspot cycle by, on average, 5.5 years. It is concluded that the observed weak large-scale solar magnetic field is not the product of the decay of strong active-region fields. Based on the new data, the level of the current (23rd) solar-activity cycle and some aspects of solar-cycle theory are discussed. © 2000 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]