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 spor...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.展开更多
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...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.展开更多
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 ...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.展开更多
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 e...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.展开更多
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 loc...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.展开更多
Simultaneous observations of the solar eclipse on 06/01/2011 were carried out using a Foucault pendulum and a torsion balance. The instruments were installed in a salt mine, where the interference was minimal. Both in...Simultaneous observations of the solar eclipse on 06/01/2011 were carried out using a Foucault pendulum and a torsion balance. The instruments were installed in a salt mine, where the interference was minimal. Both instruments clearly reacted to the eclipse. We conclude that these reactions should not be considered as being gravitational effects.展开更多
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...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.展开更多
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 stron...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,展开更多
Eclipse induced changes in solar radiation is a common interest of scientists all over the world. The disturbance of the heat balance along the supersonic travel of the trajectory of the Moon’s shadow could generate ...Eclipse induced changes in solar radiation is a common interest of scientists all over the world. The disturbance of the heat balance along the supersonic travel of the trajectory of the Moon’s shadow could generate gravity waves during solar eclipse, which results a reduction in the concentration of ozone layer in the stratosphere. We, in this context, conducted some experiments to detect the possible radiations reaching the surface of the earth and the impact of such radiation in seawater during the recent total and annular solar eclipses. This is the first time that the variation in pH value of seawater during solar eclipse is examined, and the experimental data demonstrated that the solar eclipse phenomenon affects the pH value of seawater due to the shorter wavelength radiations received on the surface of the earth. The reduction is around 20% and 40% of the difference between ordinary water and seawater during total and annular eclipses respectively. The multidisciplinary influences of these findings are addressed.展开更多
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...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。展开更多
During total solar eclipses, we can observe the outer atmospheric layers of the sun (chromosphere and corona). The solar corona extends to several solar radii depending on the sunspot cycle. Basic coronal structures s...During total solar eclipses, we can observe the outer atmospheric layers of the sun (chromosphere and corona). The solar corona extends to several solar radii depending on the sunspot cycle. Basic coronal structures such as polar streamers, helmet type structures were?observed?during the 2006 total solar eclipse. Our total solar eclipse 2006 observations through?both White light corona and H-Alpha filter allowed us to describe coronal structures and Prominence Activity. We found that the solar corona is extended to 4 times of solar radii, the existence different zones of white light corona were shown, moreover, we compared the defined features of solar corona at different observing locations along the track of total solar eclipse 2006. The solar limb activity was studied during both of partial and total eclipse phases by using H-Alpha and white light observations from Salloum, Egypt. We got same prominence activity during partial and total phases of the solar eclipse and recorded three prominences on solar limb. Finally, our processed image in a good agreement with the published?processed images?was?observed from different locations along the track of total eclipse,?added, similar magnetic field structure shown in our processed image and published one.展开更多
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 fo...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.展开更多
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 c...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.展开更多
<span style="white-space:normal;">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 ma...<span style="white-space:normal;">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 21</span><sup style="white-space:normal;">st</sup><span style="white-space:normal;">, 2020 in Helwan, Egypt (Lat. 29.866</span>°<span style="white-space:normal;">N and Long. 31.20</span>°<span style="white-space:normal;">E) has been made. A pyrheliometer for measuring the direct solar radiation, in three different bands;direct yellow (</span><em style="white-space:normal;">Y</em><span style="white-space:normal;">), direct red (</span><em style="white-space:normal;">R</em><span style="white-space:normal;">), direct infrared (</span><em style="white-space:normal;">IR</em><span style="white-space:normal;">), and also the total direct band (</span><em style="white-space:normal;">I</em><span style="white-space:normal;">);A pyranometers for measuring the different components of global solar radiation (</span><em style="white-space:normal;">G</em><span style="white-space:normal;">), global ultraviolet (</span><em style="white-space:normal;">G<sub>UV</sub></em><span style="white-space:normal;">), global infrared (</span><em style="white-space:normal;">G<sub>IR</sub></em><span style="white-space:normal;">) 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 (</span><em style="white-space:normal;">I</em><span style="white-space:normal;">, </span><em style="white-space:normal;">Y</em><span style="white-space:normal;">, </span><em style="white-space:normal;">R</em><span style="white-space:normal;"> and </span><em style="white-space:normal;">IR</em><span style="white-space:normal;">) are greatly affected by the eclipse. The diffuse fraction </span><em style="white-space:normal;">K<sub>d</sub></em><span style="white-space:normal;"> is higher in the early time, before the partial eclipse, but during the partial annular eclipse time </span><em style="white-space:normal;">K<sub>d</sub></em><span style="white-space:normal;"> values are suffers variation and through the day, where the values of </span><em style="white-space:normal;">K<sub>d</sub></em><span style="white-space:normal;"> lies between </span><em style="white-space:normal;">K<sub>t</sub></em><span style="white-space:normal;"> and</span><em style="white-space:normal;"> K<sub>UV</sub></em><span style="white-space:normal;">. The values of direct infrared solar radiation are dominant before and after the partial annular solar eclipse. The intensity of color bands (W<span style="white-space:nowrap;">∙</span>m</span><sup style="white-space:normal;"><span style="white-space:nowrap;">−</span>2</sup><span style="white-space:normal;"><span style="white-space:nowrap;">∙</span>nm</span><sup style="white-space:normal;"><span style="white-space:nowrap;">−</span>1</sup><span style="white-space:normal;">) are </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">3 ></span><em style="white-space:normal;"> DIB</em><span style="white-space:normal;">2 > </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">4, and </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">1 is opposite direction with </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">3 and </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">2, the highest intensity is direct red and the lowest intensity is the direct infrared. The highest values of extinction coefficient in (</span><em style="white-space:normal;">G<sub>IR</sub></em><span style="white-space:normal;">) solar radiation and the lowest values occur in (</span><em style="white-space:normal;">G<sub>UV</sub></em><span style="white-space:normal;">) solar radiation, while the values of (</span><em style="white-space:normal;">G</em><span style="white-space:normal;">) 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.</span>展开更多
During the 2008 total solar eclipse, the coronal emission lines were observed by using optical fibre spectrometric and polarization imaging system in near infrared waveband. The profiles of the coronal emission lines ...During the 2008 total solar eclipse, the coronal emission lines were observed by using optical fibre spectrometric and polarization imaging system in near infrared waveband. The profiles of the coronal emission lines including Fe XIII 10747 , 10798 and He I 10830 were obtained with dispersion of 0.5 /pix. The intensity of Fe XIII 10747 remained unchanged in the two different coronal regions while the intensity of He I 10830 varied considerably in the two coronal locations no matter whether the prominence appeared or not. The coronal polarization images were observed at Fe XI 7892 with a bandpass of 30 in a series of exposure times.展开更多
Like ancient people at other places of the world, the ancient Chinese lived in awe of the Sun. As they felt solar eclipses extremely significant events, they closely observed the occurrence of solar eclipse. Ancient a...Like ancient people at other places of the world, the ancient Chinese lived in awe of the Sun. As they felt solar eclipses extremely significant events, they closely observed the occurrence of solar eclipse. Ancient astronomers further realized very early that solar eclipses were one of the important astronomical phenomena to revise and improve the ancient calendar. Interestingly, ancient emperors regarded solar eclipses as warnings from heaven that might affect the stability of their throne. Consequently, observing and recording solar eclipses became official, which dated far back to ancient China when numerous relevant descriptions were recorded in historical books. These records contribute substantially to China as an ancient civilization, as well as to the research of the long-term variation of the rotation rate of the Earth during >2000 years before the 17th century. This paper briefly reviews the perception, observations and recording of solar eclipses by ancient Chinese astronomers.展开更多
基金the National Natural Science Foundation of China(49984001)
文摘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.
文摘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.
基金supported by the B-type Strategic Priority Program of the Chinese Academy of Sciences (XDB41000000)the National Natural Science Foundation of China (41831070, 41974181)+5 种基金the Open Research Project of Large Research Infrastructures of the Chinese Academy of Sciences, “Study of the interaction between low- and mid-latitude atmosphere and ionosphere based on the Chinese Meridian Project.”supported by the National Natural Science Foundation of China (41904138)the National Postdoctoral Program for Innovative Talents (BX20180286)the China Postdoctoral Science Foundation (2018M642525)the Fundamental Research Funds for the Central UniversitiesThe National Center for Atmospheric Research is sponsored by the National Science Foundation。
文摘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.
文摘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.
基金Supported by the National Natural Science Foundation of China
文摘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.
文摘Simultaneous observations of the solar eclipse on 06/01/2011 were carried out using a Foucault pendulum and a torsion balance. The instruments were installed in a salt mine, where the interference was minimal. Both instruments clearly reacted to the eclipse. We conclude that these reactions should not be considered as being gravitational effects.
基金Chinese Joint Seismological Science Foundation (197048).
文摘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.
基金supported by NSFC grants 11373065,11527804,41231069 and 41574166the Recruitment Program of Global Experts of Chinathe Max Planck Partner Group program
文摘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,
文摘Eclipse induced changes in solar radiation is a common interest of scientists all over the world. The disturbance of the heat balance along the supersonic travel of the trajectory of the Moon’s shadow could generate gravity waves during solar eclipse, which results a reduction in the concentration of ozone layer in the stratosphere. We, in this context, conducted some experiments to detect the possible radiations reaching the surface of the earth and the impact of such radiation in seawater during the recent total and annular solar eclipses. This is the first time that the variation in pH value of seawater during solar eclipse is examined, and the experimental data demonstrated that the solar eclipse phenomenon affects the pH value of seawater due to the shorter wavelength radiations received on the surface of the earth. The reduction is around 20% and 40% of the difference between ordinary water and seawater during total and annular eclipses respectively. The multidisciplinary influences of these findings are addressed.
基金supported by NASA grant NNX17AH71GNASA LWS funding support (NNX15AB83G)+1 种基金the DoD Multidisciplinary Research Program of the University Research Initiative (MURI) project ONR15FOA-0011NAF is supported in part by AGS-1552188/47950519C75
文摘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。
文摘During total solar eclipses, we can observe the outer atmospheric layers of the sun (chromosphere and corona). The solar corona extends to several solar radii depending on the sunspot cycle. Basic coronal structures such as polar streamers, helmet type structures were?observed?during the 2006 total solar eclipse. Our total solar eclipse 2006 observations through?both White light corona and H-Alpha filter allowed us to describe coronal structures and Prominence Activity. We found that the solar corona is extended to 4 times of solar radii, the existence different zones of white light corona were shown, moreover, we compared the defined features of solar corona at different observing locations along the track of total solar eclipse 2006. The solar limb activity was studied during both of partial and total eclipse phases by using H-Alpha and white light observations from Salloum, Egypt. We got same prominence activity during partial and total phases of the solar eclipse and recorded three prominences on solar limb. Finally, our processed image in a good agreement with the published?processed images?was?observed from different locations along the track of total eclipse,?added, similar magnetic field structure shown in our processed image and published one.
基金under bi-lateral project DEAREST(project number:SCHU 1103/15-1)funded by German Research Foundation(DFG)Ministry of Science and Technology of Taiwan(MOST)
文摘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.
基金Project supported by the National Natural Science Foundation of China(Grant No.19973012).
文摘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.
文摘<span style="white-space:normal;">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 21</span><sup style="white-space:normal;">st</sup><span style="white-space:normal;">, 2020 in Helwan, Egypt (Lat. 29.866</span>°<span style="white-space:normal;">N and Long. 31.20</span>°<span style="white-space:normal;">E) has been made. A pyrheliometer for measuring the direct solar radiation, in three different bands;direct yellow (</span><em style="white-space:normal;">Y</em><span style="white-space:normal;">), direct red (</span><em style="white-space:normal;">R</em><span style="white-space:normal;">), direct infrared (</span><em style="white-space:normal;">IR</em><span style="white-space:normal;">), and also the total direct band (</span><em style="white-space:normal;">I</em><span style="white-space:normal;">);A pyranometers for measuring the different components of global solar radiation (</span><em style="white-space:normal;">G</em><span style="white-space:normal;">), global ultraviolet (</span><em style="white-space:normal;">G<sub>UV</sub></em><span style="white-space:normal;">), global infrared (</span><em style="white-space:normal;">G<sub>IR</sub></em><span style="white-space:normal;">) 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 (</span><em style="white-space:normal;">I</em><span style="white-space:normal;">, </span><em style="white-space:normal;">Y</em><span style="white-space:normal;">, </span><em style="white-space:normal;">R</em><span style="white-space:normal;"> and </span><em style="white-space:normal;">IR</em><span style="white-space:normal;">) are greatly affected by the eclipse. The diffuse fraction </span><em style="white-space:normal;">K<sub>d</sub></em><span style="white-space:normal;"> is higher in the early time, before the partial eclipse, but during the partial annular eclipse time </span><em style="white-space:normal;">K<sub>d</sub></em><span style="white-space:normal;"> values are suffers variation and through the day, where the values of </span><em style="white-space:normal;">K<sub>d</sub></em><span style="white-space:normal;"> lies between </span><em style="white-space:normal;">K<sub>t</sub></em><span style="white-space:normal;"> and</span><em style="white-space:normal;"> K<sub>UV</sub></em><span style="white-space:normal;">. The values of direct infrared solar radiation are dominant before and after the partial annular solar eclipse. The intensity of color bands (W<span style="white-space:nowrap;">∙</span>m</span><sup style="white-space:normal;"><span style="white-space:nowrap;">−</span>2</sup><span style="white-space:normal;"><span style="white-space:nowrap;">∙</span>nm</span><sup style="white-space:normal;"><span style="white-space:nowrap;">−</span>1</sup><span style="white-space:normal;">) are </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">3 ></span><em style="white-space:normal;"> DIB</em><span style="white-space:normal;">2 > </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">4, and </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">1 is opposite direction with </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">3 and </span><em style="white-space:normal;">DIB</em><span style="white-space:normal;">2, the highest intensity is direct red and the lowest intensity is the direct infrared. The highest values of extinction coefficient in (</span><em style="white-space:normal;">G<sub>IR</sub></em><span style="white-space:normal;">) solar radiation and the lowest values occur in (</span><em style="white-space:normal;">G<sub>UV</sub></em><span style="white-space:normal;">) solar radiation, while the values of (</span><em style="white-space:normal;">G</em><span style="white-space:normal;">) 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.</span>
基金Supported by the National Natural Science Foundation of China (Grant No. 10843003)
文摘During the 2008 total solar eclipse, the coronal emission lines were observed by using optical fibre spectrometric and polarization imaging system in near infrared waveband. The profiles of the coronal emission lines including Fe XIII 10747 , 10798 and He I 10830 were obtained with dispersion of 0.5 /pix. The intensity of Fe XIII 10747 remained unchanged in the two different coronal regions while the intensity of He I 10830 varied considerably in the two coronal locations no matter whether the prominence appeared or not. The coronal polarization images were observed at Fe XI 7892 with a bandpass of 30 in a series of exposure times.
文摘Like ancient people at other places of the world, the ancient Chinese lived in awe of the Sun. As they felt solar eclipses extremely significant events, they closely observed the occurrence of solar eclipse. Ancient astronomers further realized very early that solar eclipses were one of the important astronomical phenomena to revise and improve the ancient calendar. Interestingly, ancient emperors regarded solar eclipses as warnings from heaven that might affect the stability of their throne. Consequently, observing and recording solar eclipses became official, which dated far back to ancient China when numerous relevant descriptions were recorded in historical books. These records contribute substantially to China as an ancient civilization, as well as to the research of the long-term variation of the rotation rate of the Earth during >2000 years before the 17th century. This paper briefly reviews the perception, observations and recording of solar eclipses by ancient Chinese astronomers.