Flux Variations in Lines of Solar EUV Radiation beyond Flares in Cycle 24

Geomagnetism and Aeronomy - Studies in the extreme ultraviolet (EUV) and X-ray ranges of the solar spectrum are important due to the active role of radiation of these ranges in the formation of the...     

Contributions from Different-Type Active Regions Into the Total Solar Unsigned Magnetic Flux

Geomagnetism and Aeronomy - Data set acquired by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) during 2010–2017 allowed us to classify active regions...     

Interaction of Solar-Flare-Accelerated Nuclei with the Solar Photosphere and the Isotopic Composition of the Solar Wind

The nuclear interactions of solar-flare-accelerated protons and ions with the solar atmosphere and the deeper layers of the Sun lead to the formation of several stable and radioactive isotopes. This article examines the GEANT4 depth profiles of ²H, ³H, ³He, ⁶Li, ⁷Li, ¹⁰Be, and ¹⁴C. When accelerated particles pass through a layer of 0.1–2 g cm^–2, ⁶Li, ⁷Li, ¹⁰Be, and ¹⁴C isotopes form in sufficient amounts to explain their anomalous abundances in lunar soil samples. It is assumed that they escape into interplanetary space with coronal mass ejections immediately after the flare.     

Cycle Variations in the Photospheric and Interplanetary Magnetic Field and Solar Wind Parameters

Geomagnetism and Aeronomy - The influence of cycle changes in the polar and nonpolar photospheric magnetic fields on variations in the interplanetary magnetic field (IMF) and the solar wind...     

Influence of Cycle Variations in the Global Solar Magnetic Field on Characteristics of the Interplanetary Plasma

Geomagnetism and Aeronomy - Regularities of the spatial and temporal variation in the plasma parameters of the interplanetary medium in solar cycles 21–24 are studied based on the data from...     

Cyclic Variations,Magnetic Morphology,and Complexity of Active Regions in Solar Cycles 23 and 24

Geomagnetism and Aeronomy - In this paper, 2046 active regions of solar cycle 23 and 1507 active regions of solar cycle 24 observed during the period from May 1996 to December 2018 have been...     

Variations in the Intensity of the Earth's Magnetic Field

The Earth's main magnetic field can be approximated by an axial, geocentric dipole. The remaining non-dipole field is much smaller and is a regional rather than a global feature – quite large changes can occur in a few ka. This review is concerned with changes in the dipole component of the geomagnetic field, and one of the problems is in separating the non-dipole from the dipole contributions to the field. Unlike the many determinations of the direction of the Earth's magnetic field in the past (which have led to fundamental contributions to our understanding of plate tectonics and shown that the field can on occasion reverse its polarity), estimates of the intensity of the field are comparatively few, especially before the Holocene. This is mainly the result of experimental difficulties in obtaining reliable measurements of the field. These problems are discussed in some detail and are followed by a short account of archaeomagnetic intensities and results from Hawaii where many of the first determinations were obtained. Measurements for the last 100 ka from both lavas and lacustrine and oceanic sediments are reviewed and results from different areas compared. An asymmetric saw-tooth pattern has been observed in some of the records over the last few Ma, and this rather controversial question is discussed. Finally an account is given of the far more limited data on palaeointensities in earlier times.A short discussion is given of the interpretation of coherent short wavelength variations which are observed in many marine magnetic profiles. Although short reversals of the field may be responsible for some of these tiny wiggles, it is more likely that in general they are the result of changes in the strength of the Earth's magnetic field.     

Dynamic Model of Magnetic Flux Ropes

Geomagnetism and Aeronomy - Developing ideas of the paper Zaitsev and Stepanov (2018) with regards to activation of a current-carrying filament with an increase in electric current, in which the...     

Influence of the Solar Wind and Geomagnetic Activity Parameters on Variations in the Cosmic Ray Cutoff Rigidity during Strong Magnetic Storms

Geomagnetism and Aeronomy - The correlation between the variations of geomagnetic cutoff rigidity ΔR and interplanetary parameters and the Dst index of geomagnetic activity during one moderate...     

Temporal Variations of Chlorinated Solvents in Abstraction Wells

Data obtained during an organic water quality survey of abstraction (pumping) wells in the Triassic Sandstone Aquifer of Birmingham (U.K.) indicate that there are important variations of chlorinated solvent concentrations with time. Short-term observation of solvent concentrations with elapsed pumping time indicates widely differing well responses; such observations are important in establishing good sampling protocols. Long-term monitoring indicates that solvent concentrations, particularly trichloroethene, are often stable with time. When large solvent variations do occur, these are shown to be due to the variation in the abstraction history of the well or significant migration of solvent plumes during the monitoring period. The latter effect is particularly exemplified by rising trends in 1,1,1-trichlroethane concentrations. The changes observed in solvent concentrations during long-term monitoring of the Birmingham Aquifer are slow to occur, but often large.     

Estimation of Solar Activity Impact on the Outgoing Infrared-Radiation Flux

Geomagnetism and Aeronomy - A parameterization of the mechanism of solar activity impact on the Earth’s troposphere developed by the authors is proposed for a model of outgoing longwave...     

Diagnostics of Turbulent Dynamo from the Flux Emergence Rate in Solar Active Regions

Line-of-sight magnetograms acquired by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamic Observatory (SDO) and by the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO) for 14 emerging ARs were used to study the derivative of the total unsigned flux–the flux emergence rate, R(t). We found that the emergence regime is not universal: each AR displays a unique emergence process. Nevertheless, two types of the emergence process can be identified. First type is a “regular” emergence with quasi-constant behavior of R(t) during a 1–3 day emergence interval with a rather low magnitude of the flux derivative, R_max = (0.57 ± 0.22) × 10²² Mx day^–1. The second type can be described as “accelerated” emergence with a long interval (>1 day) of the rapidly increasing flux derivative R(t) that result in a rather high magnitude of R_max= (0.92 ± 0.29) × 10²² Mx day^–1, which later changes to a very short (about a one third of day) interval of R(t) = const followed by a monotonous decrease of R(t). The first type events might be associated with emergence of a flux tube with a constant amount of flux that rises through the photosphere with a quasi-constant speed. Such events can be explained by the traditional largescale solar dynamo generating the toroidal flux deep in the convective zone. The second-type events can be interpreted as a signature of sub-surface turbulent dynamo action that generates additional magnetic flux (via turbulent motions) as the magnetic structure makes its way up to the solar surface.     

Nonequilibrium Effects in Atmospheric Perturbations Caused by Solar Radiation Flux

The effects of atmospheric nonequilibrium in the generation of wave perturbations due to the solar radiation flux are studied. Equations of nonequilibrium thermodynamics are used to perform an assessment of the channels of solar energy transformation into the atmosphere for different altitudes. As a result of calculations of the dispersion relation for a nonequilibrium atmosphere, we consider how the flux of solar radiation changes the spectrum of natural atmospheric oscillations at different altitudes and for different solar activities. A qualitative relation between the results of wave spectra calculations and the data of ionosphere dynamics observations for different intensities of the solar radiation flux has been established.     

Nonaxisymmetric Component of the Solar Photospheric Magnetic Field

Geomagnetism and Aeronomy - The longitudinal asymmetry of the photospheric magnetic field distribution is studied based on data from the Kitt Peak National Solar Observatory (synoptic maps for...     

Dependence of Atmospheric Transparency Variations on Solar Activity

The atmospheric spectral transparency variations at 344 nm and 369 nm, averaged at eight Soviet stations between 69°N and 55°N, have been compared with sunspot numbers, or Wolf numbers (WN). The data were taken for the seasonal interval May-August during the period 1972 – 1989. Good negative correlations –0.76 and –0.82 have been found. The correlation coefficient between aerosol extinction at 344 nm and WN is equal to +0.75. Insignificant correlation is found for the transparency variations at 344 nm for stations situated to the south of latitude 50°. The best correlation with WN for both transparency and aerosol extinction at northern stations occurs for the shift of WN ahead of the optical parameters by 6 months. The connection of transparency with cosmic rays in Apatity is also examined. It displays a sign opposite to that for WN, smaller values of the correlation coefficient, and an improbable shift of transparency ahead of cosmic ray intensity. The relative changes of the transparency during a solar cycle can be evaluated at 10% in the ozone-free UVA region     

新疆天山地区b值时空变化特征

通过分析新疆天山中东段和南天山西段地区2000年以来的以最小完整性震级(Magnitude of completeness,Mc)下限为基础的b值时空扫描图像,得到天山中东段和南天山西段两个不同区域的b值异常指标,研究结果表明:1天山中东段地区b值背景为0.705±0.004;南天山西段b值背景为0.583±0.003,略低于天山中东段b值背景水平。2 2003—2012年研究区内4次6级以上地震前,震中位置的b值多数处于低值状态,而震中附近区域其b值相对较高,反映出应力积累变化的主要方向。     

Spatial and Temporal Variations in the Formation of the Kamennaya Steppe Water Regime

The processes of water regime formation in the catchment areas of deans in the Kamennaya Steppe are studied based on the data of many-year field experiments. Certain regular variations are recognized in the characteristics of the Kamennaya Steppe hydrological and ecological condition and their correlation with anthropogenic and climatic factors is established.     

Spatial and Temporal Dependence of Temperature Variations Induced by Atmospheric Pressure Variations in Shallow Underground Cavities

Pressure-induced temperature (PIT) variations are systematically observed in the atmosphere of underground cavities. Such PIT variations are due to the compressibility of the air, damped by heat exchange with the rock surface. It is important to characterize such processes for numerous applications, such as the preservation of painted caves or the assessment of the long-term stability of underground laboratories and underground waste repositories. In this paper we thoroughly study the spatiotemporal dependence of the PIT response versus frequency using vertical and horizontal profiles of temperature installed in an abandoned underground quarry located in Vincennes, near Paris. The PIT response varies from about 20 × 10^?3°C hPa^?1 at a frequency of 2 × 10^?4 Hz to 2–3 × 10^?3°C hPa^?1 at a frequency of one cycle per day. An analytical expression based on a simple heat exchange model accounts for the observed features of the PIT response and allows for correcting the measured time series, having standard deviations of about 10^?2°C, to residual variations with a standard deviation of about 2 × 10^?3°C. However, a frequency-dependent attenuation of the response, corresponding to a reduction in amplitude with a factor varying from 2 to 3, is observed near the walls. This effect is not included in the simple analytical expression, but it can be accounted for by a one-dimensional differential equation, solved numerically, where temperature variations in the atmosphere are damped by an effective radiative coupling with the rock surface, complemented by a diffusive coupling near the walls. The TIP response is observed to remain stable over several years, but a large transient enhancement of about a factor of two is observed near the roof at one location from July to October 2005. In a cavity located below the Paris Observatory, an additional contribution is identified in the PIT response function versus frequency for frequencies smaller than 2 × 10^?5 Hz. This contribution can be described using a modified analytical expression that includes the effect of heat diffusion into the surrounding rock. Using this expression, in this case also, the temperature time series can then be corrected, giving a residual standard deviation smaller than 1.6 × 10^?3°C. Transient temporal variations of the PIT response are observed in all sites, with possible nonlinear components in the PIT. Such effects are not properly understood at this stage, and limit the reduction of time series to standard deviations of the order of 2 × 10^?3°C, and consequently limit the search for new transient or seasonal temperature signals, for example due to the presence of tiny heat sources in the cavity or to geodynamical effects.     

Variations of Solar Activity Cycles in the Late Pleistocene Lacustrine Ribbon Clay Rhythms

Geomagnetism and Aeronomy - In order to study possible changes in solar activity in the remote transitional climatic period of Younger Dryas cooling (12 700–11 600 ± 100...