Polar and Low-Latitude Faculae in Activity Cycles 23–24

Geomagnetism and Aeronomy - 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...     

Drift of Polar Prominences in Solar Cycles 13–24

Geomagnetism and Aeronomy - 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...     

Results of Spectral Corona Observations in Solar Activity Cycles 17–24

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 ?tít 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.     

Latitudinal Profiles of the Photospheric Magnetic Field in Solar Cycles 19–21

For various groups of photospheric magnetic fields differing in strength, averaged synoptic maps have been obtained from the data of the Kitt Peak National Solar Observatory (1976–2003). The latitudinal profiles of magnetic field fluxes are considered individually for each 5-G field strength interval. Changes in the maxima of the latitude profiles and their localization in the latitude are studied. The results are evidence that the latitudinal distribution of the magnetic fields changes significantly at field strengths of 5, 15, and 50 G. The magnetic flux for groups of fields differing in strength decreases monotonically as the strength increases, starting from B > 5 G; the fluxes of the southern hemisphere exceed those of the northern hemisphere. A very special group is formed by the weakest fields with B < 5 G, which are opposite in phase to stronger fields in terms of localization and time changes.     

Coronal Holes as Tracers of the Sun’s Global Magnetic Field in Cycles 21–23 of Solar Activity

The dependences of the number and parameters of non-polar coronal holes (CHs) on characteristics of the Sun’s global magnetic field (GMF) are investigated in cycles 21–23 of solar activity (1976–2012) based on data from the CH catalog of the Mountain Astronomical Station of the Main (Pulkovo) Astronomical Observatory of the Russian Academy of Sciences. The influence of variations in the GMF structural arrangement on the CH number and parameters is considered. It is shown that the more stable and steadystate the GMF topology is in the cycle, the higher are the GMF values. The majority of CHs form over periods of stable GMF structure. With a growth in the rate of structural GMF changes, the CH number and the values of all CH parameters decrease. The correlation between the area, extension in latitude and longitude, and magnetic flux of CHs and the intensity of both the calculated coronal field and the observed large-scale photospheric magnetic field is higher in cycles with larger magnetic-field values and with a more stable GMF structure. Non-polar CHs are divided into three groups depending on the GMF value and a rate of the structural GMF rearrangement.     

Asymmetry of Sunspot Distribution in Solar Cycles 12–24 and the Gnevyshev–Ohl Rule

Geomagnetism and Aeronomy - The nonaxisymmetric component of the sunspot distribution (longitudinal asymmetry) is considered based on the Greenwich–USAF/NOAA data for 1874–2016. Vector...     

Rotation of the Solar Corona from Observations of Radio and X-Ray Solar Emission for Solar Activity Cycles 22–24

Geomagnetism and Aeronomy - The values of the radio and X-ray solar flux over the last three cycles of solar activity were studied for the presence of quasi-periodic oscillations via the...     

Positive and Negative Photospheric Fields in Solar Cycles 21–24

Geomagnetism and Aeronomy - The distribution of positive and negative photospheric fields is considered based on the synoptic maps of the photospheric magnetic field from the National Solar...     

Study of Distribution and Asymmetry in Soft X-ray Flares over Solar Cycles 21–24

Geomagnetism and Aeronomy - This paper investigates the North–South (N–S) as well as East–West (E–W) distribution and asymmetry in Soft X-ray flares (SXR) activity during...     

Latitudinal distribution of iodine in sediments in the Chukchi Sea and the Bering Sea

Iodine is a trace element playing an important role in vital activities of organisms. It is im-portant for human bodys thyroid gland. Deficient or excessive iodine will not only influence hu-man health but also cause feeblemindedness, so great attention h…     

Seismic Activity and Structures of the Crust and Upper Mantle in the Areas of Source Zones of the Largest Earthquakes in the Altai–Sayan Region

The results of studies of the shear wave attenuation field in source zones of the 2003 Chuya, 1970 Ureg-Nur, 1991 Busingol, 2011 Sayan, and 2011–2012 Tuva earthquakes are presented. Attenuation fields in these source zones include blocks with a high Q-factor and linear weakened zones. The surface ruptures from the mainshocks of the 2003 Chuya and 2011–2012 Tuva earthquakes are located in the zones of strong attenuation. Epicenters of the mainshocks are located where the maximum contrast in attenuation is observed. In the source zones of large earthquakes in the Altai–Sayan region or near them, the zones similar to so-called seimogenic bodies described in the literature are found. These objects tend to linear zones with high attenuation and are characterized by an increased density of deepened earthquakes and also by deformations of near-vertical elongation. The obtained data suggest that the fluid factor could play certain role in the occurrence of large earthquakes in the Altai–Sayan region.     

Height stratification and polar reversal of the Sun’s magnetic fields in cycles 21–23

Using calculations of the magnetic field in the solar atmosphere in the potential approximation, it is shown that, (1) as distance R from the Sun’s center grows, the area of the positive magnetic field (S _+field) in 10-deg latitude zones tends to 100% (0%) in the neighborhood of the solar minimum. At the distance R = 2.5R _⊙(R _⊙ is the solar radius), these values of the positive field are observed during ≈(12–55) Carrington rotations (CRs) for solar minima between neighboring cycles; (2) polar magnetic field reversals can occur repeatedly. Note that a polar reversal at large heights ends by 6–16 Carrington rotations earlier than on the Sun’s surface. On the Sun’s surface, a field polar reversal begins earlier at lower latitudes than at high ones; (3) for each longitude at different Rs and separately for each solar hemisphere the radial component of the field was averaged on synoptic maps in the 0°–40° latitude range. It is established that the T _R rotation periods of the boundaries between the sectors (areas of longitudes with the same sign of the averaged field) can be shorter than, longer than, and equal to Carrington solar rotation period T _CR. It turned out that boundaries with T _R < T _CR are observed at all heights, while boundaries with T _R > T _CR are observed at relatively small heights.     

Characteristic Features of Solar Cosmic Rays in the 21st–24th Solar-Activity Cycles According to Data from Catalogs of Solar Proton Events

Geomagnetism and Aeronomy - Homogeneous series of solar cosmic-ray events for four solar-activity cycles against the background of decreased activity in cycles 23 and 24 are considered. The number...     

Latitude-Longitude Characteristics of the North–South Asymmetry of Solar Activity

Geomagnetism and Aeronomy - The characteristics of the latitude-longitude distribution of the north–south (NS) asymmetry of the number of sunspots for the period of 1874–2013 are...     

Characteristics of the Activity of the Lintong-Chang＇an Fault in the Late Pleistocene

Analysis of fault outcrops and trench sections indicates fault displacements of 0.2m - 6.0 m on the bottom paleosol layer of the Epipleistocene with the maximum rate of 0.047 mm/a and an average displacement of 1.1 meters. The activity appears as fissures on the fault surface in the late Epipleistocene and there is no obvious displacement. The fault activity is weak and the most active segment is the Bailuyuan segment.     

Activity of Hawaiian Volcanoes during the years 1940–1950

Summit eruptions of Mauna Loa, on the Island of Hawaii, occurred in 1940 and 1949, and flank eruptions in 1942 and 1950. Lava poured out in 1940 and 1942 was about equal in amount, totaling approximately 76 million cubic meters in each eruption. The 1949 eruption was somewhat smaller, liberating approximately 59 million cubic meters. The 1950 eruption was one of the largest on record, producing five large lava flows and several smaller ones, totaling approximately 459 million cubic meters. Three of the 1950 flows entered the sea. In 1942 a lava flow threatened the city of Hilo, and was bombed from the air in an effort to divert it. Calculations indicate that the gas content of the lava extruded during the 1940 eruption probably was in the vicinity of one percent by weight of the total magma. Other calculations indicate the viscosity of fluid Hawaiian lava to be in the range of 10³ to 10⁵ poises. Temperature readings on the 1950 lava ranged from 1090⁰ to 900⁰ C. Kilauea Volcano showed signs of uneasiness in 1944, with an apparent increase of magmatic pressure indicated by outward tilting of the moutain flanks and a series of earthquakes progressing toward the surface. In December 1950 a series of earthquakes accompanied a subsidence of the summit of Kilauea Volcano.     

Geochemical types of natural waters in the interfluve of the Enzor’yakhi and the Yun’yakhi (eastern slope of the Polar Urals)

Natural-water chemistry in the interfluve of the Enzor’yakhi and the Yun’yakhi rivers (the eastern slope of the Polar Urals) is characterized in terms of the ratios of major ions belonging to hydrocarbonate calcium-magnesium and magnesium-calcium chemical types. From the viewpoint of evolution of the water-rock system in the region, five geochemical types of water were identified by the degree of their equilibrium with secondary minerals, reflecting different formation conditions of their chemistry. A specific feature of the region is the formation of waters of organogenic geochemical type, which are considerably enriched by organic matter, determining the specifics of migration of some chemical elements in such waters.     

Dynamics of the Annual Variation in the Climate Variables of the Earth’s Atmosphere and Their Relation to Solar Activity

Geomagnetism and Aeronomy - In this article, the dynamics of the annual variation in the mean monthly values of temperature and precipitation is studied via the expansion of series into natural...