The possible influence of solar activity on Indian summer monsoon rainfall

The Indian summer monsoon rainfall （ISMR） plays an important role in the climate system of South Asia. Recently, studies about ISMR variations have been going into more depth. In this present paper, we mainly use the Scargle periodogram and wavelet transform methods to study the periodicity of ISMR changes between 1871 and 2004 and review the possible influence of solar activity on the rainfall. Analysis results show complicated ISMR variations have periodicities with remarkable time-variable characteristics. Investigating a possible connection between the rainfall and solar variations, we believe that solar activity affects the ISMR variations to some extent.     

Impact of solar wind tangential discontinuities on the Earth’s magnetosphere

The collision of a solar wind tangential discontinuity with the bow shock and magnetopause is considered in the scope of an MHD approximation. Using MHD methods of trial calculations and generalized shock polars, it has been indicated that a fast shock refracted into the magnetosheath originates when density increases across a tangential discontinuity and a fast rarefaction wave is generated when density decreases at this discontinuity. It has been indicated that a shock front shift under the action of collisions with a tangential discontinuity is experimentally observed and a fast bow shock can be transformed into a slow shock. Using a specific event as an example, it has been demonstrated that solar wind tangential discontinuity affects the geomagnetic field behavior.     

What are the influences of solar eclipses on the equatorial electrojet?

The response of the equatorial electrojet (EEJ) to solar eclipses is studied in this work. We analyzed the magnetic field measurements obtained by three satellites, CHAMP, SAC-C and Ørsted and correlated them with ground-based observations during the eclipses. The observations show a local weakening of the EEJ after the shadow passed the dip equator. The size of the effect is, however, comparable with the day-to-day variability. In four out of five events we found the formation of a counter electrojet in the wake of the eclipse. We propose that the depression of the EEJ during an eclipse favors the formation of a counter electrojet.     

Sensitivity of the Earth’s middle atmosphere to short-term solar variability and its dependence on the choice of solar irradiance data set

We simulate the time evolution of the neutral and charged species in the terrestrial middle atmosphere using a 1-D radiative-convective model with interactive neutral and ion chemistry driven by four different sets of daily spectral solar irradiance (SSI) available in the literature for the year 2000. Obtained daily time series of ozone, hydroxyl and electron densities are used to calculate their sensitivity to the short-term SSI variability at 205 nm. All applied SSI data sets possess 27-day solar rotation cycle; however, its amplitude and phase as well as the correlation between considered SSI time series differ among data sets leading to the different behavior of the atmospheric response. Contrary, the ozone and hydroxyl sensitivities to the SSI changes during solar rotation cycle are almost identical for all applied SSI data sets in the stratosphere. In the mesosphere, the difference in correlation between SSI in Herzberg continuum and Lyman-α line in considered SSI data sets leads to substantial scatter of the sensitivity estimates based on 205 nm. Our results show that for the sensitivity analysis in the stratosphere based on the SSI at 205 nm any considered SSI data sets can be applied. For the mesosphere, where the sensitivity strongly varies among applied SSI data sets more robust results can be obtained using the sensitivity calculations based on the SSI in Lyman-α line.     

Atmosphere–ionosphere response to solar eclipse over Kharkiv on March 20, 2015

The results of the observations of aperiodic and quasi-periodic disturbances in E and F1 ionospheric layers and air temperature variations in the surface atmosphere on the day of the solar eclipse and control days are presented. The ionospheric processes were monitored by vertical sounding Doppler radar. The measurements showed that, near the time of the maximum coverage of the solar disk, the greatest decrease in the density of electrons in the layers E and F1 was ～27%, which is close to the calculated value (25%). The solar eclipse was accompanied by the generation of traveling ionospheric disturbances with a period of 8–12 min and a relative amplitude of electron density variations of ～0.6–1.5%. Because of the haze in the surface atmosphere, its temperature, which was monitored at observation points at a distance of 50–60 km from each other did not exceed 1°C near the time of the maximum eclipse magnitude.     

Influence of solar activity on variations in the density of the Earth’s upper atmosphere

This article studies long-period variations in the Earth’s upper atmosphere density over several solar activity cycles, using long-term data on the evolution of motion of three artificial satellites (Intercosmos-19, Meteor-1-2, and Cosmos-1154) in orbits at heights of 400–1000 km. The time interval when the satellites were in the orbits covered three solar activity cycles (partly the 21st, completely the 22nd, and partly the 23rd). It is found that the variations in the average density of the upper atmosphere at heights of 400–600 km in the 1980–2000 period were governed by the changes in the solar activity level.     

Climate hypersensitivity to solar forcing?

We compare the equilibrium climate responses of a quasi-dynamical energy balance model to radiative forcing by equivalent changes in CO₂, solar total irradiance (S_tot) and solar UV (S_UV). The response is largest in the S_UV case, in which the imposed UV radiative forcing is preferentially absorbed in the layer above 250 mb, in contrast to the weak response from global-columnar radiative loading by increases in CO₂ or S_tot. The hypersensitive response of the climate system to solar UV forcing is caused by strongly coupled feedback involving vertical static stability, tropical thick cirrus ice clouds and stratospheric ozone. This mechanism offers a plausible explanation of the apparent hypersensitivity of climate to solar forcing, as suggested by analyses of recent climatic records. The model hypersensitivity strongly depends on climate parameters, especially cloud radiative properties, but is effective for arguably realistic values of these parameters. The proposed solar forcing mechanism should be further confirmed using other models (e.g., general circulation models) that may better capture radiative and dynamical couplings of the troposphere and stratosphere.     

Study on geomagnetic effects of the March 9, 1997 solar eclipse in Mohe area, China

Introduction Study and observation of solar eclipse geomagnetic effects in China begun in 1936, and since then the total eclipse and total-annular eclipse occurred in Chongan of Fujian Province in 1941j, 1958, 1968, 1980, 1987, 1997 in succession. For these events, modern geomagnetic observations have been made with sufficient preparation. Plentiful solar eclipse data of geomagnetic field variation and research results have been obtained (ZHANG, et al, 1983, LIU, et al, 1986, YANG, DU, …     

Geomagnetic solar flare effect on February 4 and 6，1986 at the china Antarctic Great wall Station

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Can origin of the 2400-year cycle of solar activity be caused by solar inertial motion?

A solar activity cycle of about 2400 years has until now been of uncertain origin. Recent results indicate it is caused by solar inertial motion. First we describe the 178.7-year basic cycle of solar motion. The longer cycle, over an 8000 year interval, is found to average 2402.2 years. This corresponds to the Jupiter/Heliocentre/Barycentre alignments (9.8855 × 243). Within each cycle an exceptional segment of 370 years has been found characterized by a looping pattern by a trefoil or quasitrefoil geometry. Solar activity, evidenced by ¹⁴C tree-ring proxies, shows the same pattern. Solar motion is computable in advance, so this provides a basis for future predictive assessments. The next 370-year segment will occur between AD 2240 and 2610.     

Relationship between global seismicity and solar activities

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Geoeffectiveness of solar flares in magnetic crochet (sfe) production: II—Dependence on the detection method

During magnetic active periods, disturbances in the geomagnetic field can act as natural noise masking other magnetic variations of small amplitude. In this paper, the influence of these perturbations on the observation of the effects on Earth of solar flares (sfe) has been studied. The diurnal and monthly values of detected sfe have been obtained, as well as the temporal variation of the relative occurrence of events. These numbers show how the irregular distribution of the magnetic observatories is an important limitation in the efficiency of the detection method. Some considerations about the actual method used at the International Service on Rapid Magnetic Variations are finally presented.     

Long-term solar wind variations in the 20th–23rd solar activity cycles according to radio-astronomical data

We analyzed the variations of the interplanetary plasma parameters, obtained from radio astronomical observations of scintillations of cosmic radio sources during four 11-year cycles of solar activity, from 1966 to present. It is shown that the state of the interplanetary plasma permanently changes in conformity with cyclicity in the solar activity. In the studied time period, besides the 11-year variations in the velocity and scintillation index, there is also an increasing linear trend of these variables, which is presumably due to a secular 80–90-year cycle of solar activity. The observed differences between the 11-year variations and trends in the solar wind velocity and interplanetary scintillation index suggest that the 11-year and secular cycles have different origins. It is found that these trends occur in this time period in each link of the Sun-Earth system: in the solar activity indices, in the characteristics of the interplanetary medium, and practically in all characteristics of the geophysical, demographical, medical, and other Earth’s processes. From the entire set of facts we can conclude that most of the analyzed Earth’s processes are dominated not by anthropogenic factors, but by the effects of the secular cyclic processes of the solar activity.