Prediction of the thermospheric and ionospheric responses to the 21 June 2020 annular solar eclipse

On 21 June 2020,an annular solar eclipse will traverse the low latitudes from Africa to Southeast Asia.The highest latitude of the maximum eclipse obscuration is approximately 30°.This low-latitude solar eclipse provides a unique and unprecedented opportunity to explore the impact of the eclipse on the low-latitude ionosphere–thermosphere(I–T)system,especially in the equatorial ionization anomaly region.In this study,we describe a quantitative prediction of the impact of this upcoming solar eclipse on the I–T system by using Thermosphere–Ionosphere–Electrodynamics General Circulation Model simulations.A prominent total electron content(TEC)enhancement of around 2 TEC units occurs in the equatorial ionization anomaly region even when this region is still in the shadow of the eclipse.This TEC enhancement lasts for nearly 4.5 hours,long after the solar eclipse has ended.Further model control simulations indicate that the TEC increase is mainly caused by the eclipse-induced transequatorial plasma transport associated with northward neutral wind perturbations,which result from eclipse-induced pressure gradient changes.The results illustrate that the effect of the solar eclipse on the I–T system is not transient and linear but should be considered a dynamically and energetically coupled system.

Tomographic Study of Ionospheric Effects Associated with a Solar Eclipse

This paper studies the ionospheric effects associated with the solar eclipse of October 24th, 1995 by means of Computerized Ionospheric Tomography (CIT). Since the reconstructed profiles from experimental CIT are sporadically located in time, a time domain interpolation method based on Singular Value Decomposition (SVD) technique is proposed and applied to extract the ionospheric effects. The effects can be extracted by comparison analysis between the interpolated CIT profiles of the eclipse days and that of the reference day that are time-aligned. A series of figs have been obtained showing the attenuation of photonization effect at low altitudes and the weakening of plasma’s transportation process at high altitudes, etc. The photonization effect recovered to normal level soon after the last contact. The maximum electron density diminishing is observed about 2 h after the eclipse maximum and the effects seem vanished in the hours followed. Analysis on vertical TEC’s latitudinal-temporal variation gives similar conclusions.

Ionospheric Responses to a Total Solar Eclipse Deduced by the GPS Beacon Observations

The total electron content (TEC) data during the total eclipse of March 9, 1997 were collected, which were observed by means of nine GPS receivers located at the eastern Asia. The responses of total TEC to the eclipse were analyzed. The results show that: 1) the eclipse led to apparent decrement in TEC that lasted for six to eight hours; 2) the maximum decrement occurred after the middle of the eclipse with time delays varying from twenty minutes to about three hours; 3) the maximum absolute deviations of TEC on the eclipse day do not show a simple and consistent relationship to the maximum solar obscuration.

A Check on the Variations of Earth's Rotation with an Ancient Solar Eclipse

We address the relation between an ancient total eclipse, which occurred on A.D.1542 August 11 and the variation of Earth's rotation. The total eclipse was recorded in some ancient Chinese books, especially in local chronicles. Some of the documents include useful information for determining the location of the totality zone. The parameters of the eclipse are calculated by using the DE406 Ephemeris. A high-precision value of ΔT which expresses the variation of the Earth's rotation, of about 300 ~ 380 s, is obtained.

Remote sensing ionospheric variations due to total solar eclipse, using GNSS observations

For years great interest has been taken in the effects of physical phenomena on ionosphere structure. A total solar eclipse was visible in North America on August 21 st, 2017. This event offered a great opportunity for remote sensing the ionospheric behavior under the eclipse condition. In this study we investigated the effects of total solar eclipse on variations of Total Electron Content(TEC), and consequently deviations on regional models of Vertical TEC(VTEC), as well as variations in ionospheric scintillation occurrence. Although variations of TEC due to total solar eclipse are studied thoroughly by many authors, but the effect of solar eclipse on ionospheric scintillation has never been considered before. Our study is based on measurements from a high-rate GPS network over North America on the day of eclipse, a day before and after its occurrence, on the other hand, GPS measurements from groundbased stations on similar days were used to model TEC on the day of event, and also one day before and after it. The results of this study demonstrate that solar eclipse reduced scintillation occurrence at the totality region up to 28 percent and TEC values showed a decrease of maximum 7 TECU. Considering TEC models, our study showed apparent variations in the regional models, which confirms previous studies on ionospheric responses to eclipse as well as theoretical assumptions.

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

The geomagnetic effects of the total solar eclipse in Mohe area and the partial eclipse occurred on March 9, 1997 in China are analyzed in this paper. The geomagnetic effects of the eclipse widely distributed in China are obtained, which show H component decreases obviously and is symmetric along the latitude with a center near 33N during the eclipse time. These results of solar eclipse geomagnetic effects are the newest in recent years obtained in the largest area in China.

Monitoring the geospace response to the Great American Solar Eclipse on 21 August 2017

Since ancient times,solar eclipses have fascinated—and sometimes terrified—humankind.Solar eclipses are direct sensory experiences.As the sun vanishes from the sky,birds fall silent during the midday twilight.Modern instrumentation has enabled research into the consequences of this sudden change in irradiation within the upper atmosphere.For the first time in 26 years。

Thales of Miletus, Archimedes and the Solar Eclipses on the Antikythera Mechanism

Thales of Miletus （640？-546 BC） is famous for his prediction of the total solar eclipse in 585 BC. In this paper, the author demonstrate how Thales may have used the same principle for prediction of solar eclipses as that used on the Antikythera Mechanism. At the SEAC conference in Alexandria in 2009, the author presented the paper ＂Ten solar eclipses show that the Antikythera Mechanism was constructed for use on Sicily.＂ The best defined series of exeligmos cycles started in 243 BC during the lifetime of Archimedes （287-212 BC） from Syracuse. The inscriptions on the Antikythera Mechanism were made in 100-150 BC and the last useful exeligmos started in 134 BC. The theory for the motion of the moon was from Hipparchus （ca 190-125 BC）. A more complete investigation of the solar eclipses on the Antikythera Mechanism reveals that the first month in the first saros cycle started with the first new moon after the winter solstice in 542 BC. Four solar eclipses 537-528 BC, from the first saros cycle, and three one exeligmos cycle later, 487-478 BC, are preserved and may have been recorded in Croton by Pythagoras （ca 575-495 BC） and his school.

Observations of the solar corona during the total solar eclipse on 21 August 2017

The Sun’s tenuous outer atmosphere,the corona,emits only about one-millionth as much light as the solar surface.In ancient times the corona was observed by human beings only during total solar eclipses,when the strong emission of visible light from the photosphere was completely blocked by the Moon.In 1931,

An Ancient Solar Eclipse Record "Tian-da-yi" in the 10th Century BC

The ancient record "Tian-da-yi" (the sky darkened greatly) is identified with the solar eclipse on May 31, 976BC. This identification is demonstrated in this paper through a palaeographic, astronomical and chronological analysis. It is probably the earliest solar eclipse in Chinese history that can be so identified.

Performance of Incoming Solar Radiation Components in Partial Annular Solar Eclipse on June 21^st, 2020 in Helwan, Egypt

Observing and studying the solar radiation during solar eclipses is important in knowing the changes that occur to the environmental elements during this event. The main objective of this paper is the performance of the incoming variation of solar radiation components, global, direct and diffuse and their fractions during the partial annular solar eclipse on June 21st, 2020 in Helwan, Egypt (Lat. 29.866°N and Long. 31.20°E) has been made. A pyrheliometer for measuring the direct solar radiation, in three different bands;direct yellow (Y), direct red (R), direct infrared (IR), and also the total direct band (I);A pyranometers for measuring the different components of global solar radiation (G), global ultraviolet (GUV), global infrared (GIR) and a meteorological station to measure the different meteorological parameters. The duration of the solar eclipse was 01 h:59 m, and the maximum magnitude of the eclipse in this region was 0.449. The depression is clear at the solar radiation of all components due to the annular solar eclipse, while the depressions of the diffuse and global infrared solar radiation are lower. In all direct radiation compounds (I, Y, R and IR) are greatly affected by the eclipse. The diffuse fraction Kd is higher in the early time, before the partial eclipse, but during the partial annular eclipse time Kd values are suffers variation and through the day, where the values of Kd lies between Kt and KUV. The values of direct infrared solar radiation are dominant before and after the partial annular solar eclipse. The intensity of color bands (W∙m−2∙nm−1) are DIB3 > DIB2 > DIB4, and DIB1 is opposite direction with DIB3 and DIB2, the highest intensity is direct red and the lowest intensity is the direct infrared. The highest values of extinction coefficient in (GIR) solar radiation and the lowest values occur in (GUV) solar radiation, while the values of (G) solar radiation occur between them. In general trend, the values of extinction coefficient during the partial eclipse are increasing, while the minimum values of extinction coefficient occur at noon time due to the air mass is less value in the noon.

Joint observation results of Na layer and ionosphere in Wuhan during the Total Solar Eclipse

During the total solar eclipse on July 22, 2009 in Wuhan, the joint observation test of Na layer and ionosphere was conducted by using the daytime observation atmospheric lidar and the GPS ionosphere detector. The results show that the full width at half maximum(FWHM) of Na layer density slightly narrowed during the total solar eclipse and broadened after the eclipse, while the height of Na peak slightly decreased in the eclipse and increased after the eclipse. These implying that Na layer changes reflect the rapid process of sunrise and sunset. The ionosphere total electron content(TEC) and the sky background light noise also presented an obvious fluctuation characteristic with the changes of solar irradiation during the process of total solar eclipse. The difference lies in that the changes of FWHM of Na layer atoms are much slower than that of ionosphere, the reason for this might be that the Na layer, after being disturbed by the total solar eclipse, will generate a series of complicated photochemical reactions and momentum transport processes, and then recombine the Na atoms. The Na atoms to be detected by the lidar need a lag process, which rightly conforms to the theoretical simulated results.

OBSERVATION OF THE SPECTRA OF SVC SOURCES MADE IN CHINA ON THE SOLAR ECLIPSE IN THREE SOLAR CYCLES (19, 20, 21)

Ⅰ. INTRODUCTION The observation of the spectra of the SVC sources is very important in the theory of the slowly varying component (SVC) and for the prediction of solar-terrestrial environment. In order to increase the spatial resolution, solar radio astronomers made used of solar eclipses to observe the SVC sources over a wide range of frequencies to ob-

A Japanese Record of an Annular Solar Eclipse and Variation of the Earth's Rotation

Although the Japanese records of central or near central solar eclipses (i.e. the total, annular and total-annular eclipses) are not very old, so long as their documents definitely recording the observational place, date and phenomenon of the eclipse or the parameters can be defined through some textual researches even if

Variation of the earth's rotation derived from timing records of solar eclipse in ancient China

In the study of variation of the earth’s rotation based on the records of some ancientastronomical events, the timing records of ancient astronomical events and phenomena, suchas solar and lunar eclises and lunar occultation, are important components of the data.The reliable records, especially those from the countries and regions with advanced an-cient astronomy and timing technology, contain valuable information on the variation

A study on excitation of atmospheric gravity waves from annular solar eclipse

Utilizing the data of microbarometric waves on ground level, radiosonde reports and solar radiations obtained from various observation stations in China during the annular solar eclipse on September 23, 1987, the mechanism ,of AGWs excited by the eclipse, the spectral characteristics and the local differences have been studied, and the results have been compared with those from the ionospheric sounding at the same time. It turns out that there were AGWs excited certainly during this annular solar eclipse, their periods are obviously in accordance with the duration of the fluctuation in the direct solar radiation.

ON THE ATMOSPHERIC GRAVITY WAVES DURING THE 23RD SEPTEMBER 1987 ANNULAR SOLAR ECLIPSE

During solar eclipse, the lunar shadow moves through the earth's atmosphere with supersonic speed. Chimonas and Hines deemed that the shock waves produced by cooling of atmosphere would induce gravity waves, and both TIDs and atmospheric pressure changes can be detected in the ionosphere and on the ground respectively. Although the IGW signals from solar eclipse are usually quite weak, they can still be detected .The pressure changes on ground level occur near the region of eclipse, but can be detected even far beyond the path of eclipse. This article is the first one to report results of detecting pressure waves caused by solar eclipse in China.Druing the 23rd September 1987 annular solar eclipse, IGWs have been detected and recorded at infrasound observatories in Urumqi, Taiyuan, Xuzhou and Suzhou, which are situated within the path of annular eclipse, as well as in Beijing and Guiyang, which are situated on the opposite sides of this path. The signals are detected by microbarometers of condenser microphone type. After analysing the waveforms of the recorded signals numerically, the wave periods and wave amplitudes are determined to be within the ranges from 10 to 60 min and from 7 to 20 Pa (peak to peak ) respectively. The results from dynamical spectral analyses show that the spectral distribution of all the gravity wave periods from various observatories is continuous and possesses a common main period of 40 min. Moreover, there are waves with even longer periods in different observatories and their appearance times are quite different.

Is the Growth of the Astronomical Unit Caused by the Allais Eclipse Effect?

In addition to the Pioneer anomaly and the Earth flyby anomaly for spacecraft, other unexplained anomalies disrupt the solar system dynamics, like the astronomical unit. We show in this paper that the Allais eclipse effect causes the major part of the growth of the length scale for the entire solar system. It is the rough disturbance on the barycenter Earth-Moon implying the Sun that was recorded in the movement of the paraconical pendulum. Earth and Moon revolve around their common center of gravity, which in turn orbits the Sun, and the perturbation of the eclipse hits this double, coupled Kepler’s movements. The thesis of the tidal friction supports that oceanic tidal friction transfers the angular momentum of the Earth to the Moon and slows down the rotation of the Earth while taking away the Moon. However, we think that there are not enough shallow seas to sanction this interpretation. The Earth-Moon tidal system might be inaccurate or unreliable in determining the Earth’s actual rotational spin-down rate. Our assertion is that the change in the Earth’s rotation is caused by a repulsive gravitational interaction during solar eclipse. The perturbation would submit to variations and distortions the region of the barycenter of the Earth-Moon system which revolves around the Sun, with the dual secular effects that the Moon spirals outwards and that the Earth-Moon system goes away from the Sun.

Astral Actions on Allais’ Pendulum Apparently Inexplicable by Classical Factors: A Point of the Situation

1) The observation by Allais of the precession of pendulums from 1954 to 1960 highlighted regularities of astral origin an in-depth analysis of which showed that, apparently, no classical phenomenon can explain them. These regularities were diurnal waves whose periods are characteristic of astral influence (the main ones being 24 h and 24 h 50 min), annual and semi-annual components, and a multi-annual component of approximately 6 years, an influence of Jupiter being a very good candidate to explain it. 2) Allais had experimentally established that all these astral influences were expressed globally on the pendulum by an action tending to call back its plane of oscillation towards a direction variable in time, and which ovalized its trajectory. In 2019 the observation of 2 pendulums in Horodnic (Romania), thanks to the use of an automatic alidade, made it possible to identify the main mechanism that, very probably, acted on the pendulum to achieve this result. This perturbation model, called “linear anisotropy”, is characterized by its “coefficient of anisotropy” η, and by the azimuth of its “direction of anisotropy”. The composition of 2 linear anisotropies is always a linear anisotropy. 3) In the search for the phenomena which could be at the origin of all what precedes, the fact that they must create an ovalization immediately eliminates some of them. 4) We have calculated the values of η corresponding to the 24 h and 24 h 50 min waves both for the observations in Horodnic and the Allais observations. The order of magnitude (some 10−7) is effectively the same in both cases. 5) Mathematically, the regularities discovered may result of a new force field but also, as Allais proposes, from the creation, under the astral influences, of a local anisotropy of the medium in which the pendulum oscillates. In the first case the length of the pendulum is involved, in the second one not. The data available do not make it possible to decide. 6) The joint exploitation, in mechanics and optics, of Allais observations and of observations by other experimenters provides additional information: a) Allais, and after him several other scientists, discovered also marked anomalies in the precession of pendulums during certain eclipses, and maybe certain other syzygies. For the few eclipses for which both something was observed and sufficient data were available (one of them being a lunar eclipse for which nothing had been published until now), it was always the above perturbation model which acted on the pendulum, but sometimes with quite exceptional magnitude. b) There are quite possible links with optics. During the observation campaign of August 1958, which had implemented both two pendulums and an optical device, all the 24 h 50 min waves were almost in phase. In the precession of the Allais pendulum, in Miller’s interferometric observations in Mont Wilson, and in Esclangon’s observations in Strasbourg, a same peculiarity is found: the extrema of the annual influence are at the equinoxes, not at the solstices.

Consideration of the Daily Variation of Gravity on the Manifestation of Gravitational Shielding

The result of mathematical and physical analysis of the daily change in gravity is presented. The subject of consideration was the manifestation of semi-daily factors in diurnal variations of gravity. The assumption is investigated, according to which the cause of the half-day factors is the gravitational shielding of the planet Earth. Gravitational shielding is considered as a function of the size and thickness of celestial bodies and growing with distance from their poles. It is concluded that the planet Earth has the property of partial gravitational shielding, and the Moon does not have enough thickness to exhibit a tangible gravitational shielding. The obtained mathematical results correspond to the existing experimental data. It is suggested that gravitational shielding is the cause of the precession of the perihelion of Mercury and the peculiarities of the manifestation of tidal processes. It is assumed that gravitational shielding is one of the main reasons for the presence of hidden substances in the Universe. It is concluded that the physical picture with mutual shielding of interaction elements corresponds to the classical ideas of Fatio and Lesage. This approach is proposed as an alternative point of view to the existing theory on the description of tidal processes. It is shown that the existing basic approach to the description of tidal forces is unsatisfactory: the factors underlying the existing approaches have values 10 times less than those observed and cannot be considered as the reason for the manifestation of half-day manifestations in the daily change in gravity. The work is a continuation of the implementation by the author of P. Dirac’s ideas about accounting for the size of microparticles in physical theory.