Showing papers on "Solar eclipse published in 1998"
TL;DR: In this article, the authors investigated in-situ generated changes of the thermosphere and ionosphere during a solar eclipse and found that the combined effects of thermal cooling and downwelling lead to an overall increase in [O], while [N(2] initially rises and then for several hours after the eclipse is below the "steady state" level.
Abstract: A modelling study is presented which investigates in-situ generated changes of the thermosphere and ionosphere during a solar eclipse. Neutral temperatures are expected to drop by up to 40 degrees K at 240 km height in the totality footprint, with neutral winds of up to 26 m/s responding to the change of pressure. Both temperatures and winds are found to respond with a time lag of 30 min after the passing of the Moon's shadow. A gravity wave is generated in the neutral atmosphere and propagates into the opposite hemisphere at around 300 m/s. The combined effects of thermal cooling and downwelling lead to an overall increase in [O], while [N(2)] initially rises and then for several hours after the eclipse is below the "steady state" level. An enhancement of [NmF2] is found and explained by the atmosphere's contraction during, and the reduced [O]/[N(2)] ratio after the eclipse.
93 citations
TL;DR: In this article, the authors presented data from first measurements of total electron content (TEC) and its gradient during the solar eclipse of March 9, 1997, obtained with the GPS-radio interferometer at Irkutsk.
Abstract: This paper presents data from first measurements of total electron content (TEC) and its gradient during the solar eclipse of March 9, 1997, obtained with the GPS-radio interferometer at Irkutsk. The interferometer consists of three receivers (one Turbo-Rogue SNR-8000, and two Ashtech Z-12) located at the vertices of a triangle and spaced by about 3–5 km. The measured TEC variations are indicative of profound changes in the ion production process in the ionosphere attendant on the solar eclipse, simultaneously in a large volume of space with a radius of at height 300 km at 300 km altitude. The delay of a minimum value of TEC with respect to the maximum phase of eclipse at 300 km altitude was about 10 min, and the depression depth of TEC growth varies from l÷3×1016m−2. By analyzing the data on TEC gradient variations, one is led to conclude that the depression of TEC growth during the eclipse is essentially independent of the longitude and of the latitude (within the observation ranges 52±6° N and 104±11° E).
82 citations
TL;DR: In this article, a procedure was developed to derive the vertical phase and group velocities of waves from measurements of ionograms, which was applied to a sequence of ionogram recorded by the digisonde portable sounder in Taiwan and found numerous waves occuring in the ionosphere during the solar eclipse of 24 October 1995.
56 citations
TL;DR: Diurnal fishes responded rapidly to decreased light levels during a total solar eclipse and sought shelter in the reef and appeared to be a direct response to changes in light level.
Abstract: Diurnal fishes responded rapidly to decreased light levels during a total solar eclipse and sought shelter in the reef. Nocturnal fishes sometimes left the cover of their daytime habitats. The activity cycles of diurnal reef fishes appear to be a direct response to changes in light level.
18 citations
TL;DR: In this article, a chirp sounder with high time delay and frequency resolution was used in the measurements for a mid-latitude, Irkutsk to Nizhny Novgorod path.
10 citations
TL;DR: The ground-based vertical radio wave propagation experiment was conducted at the frequency of 2.5 MHz to study variations in ionospheric radio wave absorption during partial solar eclipse that occurred on October 24, 1995 at Delhi (28.6°N, 77.2°E).
Abstract: The ground based vertical radio wave propagation experiment was conducted at the frequency of 2.5 MHz to study variations in ionospheric radio wave absorption during partial solar eclipse that occurred on October 24, 1995 at Delhi (28.6°N, 77.2° E). It was observed that the minimum in absorption data was four minutes earlier than the ground level eclipse totality, and an anomaly was accompanied by an abnormal sharp rise (shock-like wave structure) in absorption data around 30 minutes after the eclipse totality. Absorption during post-eclipse control days was higher compared to those on pre-eclipse control days.
7 citations
6 citations
01 Dec 1998
TL;DR: The effect of total solar eclipse on aerosol size and concentration has been studied in this paper, which reveals an increase in the aerosol number concentration in the sub-micron and micron size ranges.
Abstract: The effect of total solar eclipse on aerosol size and concentration has been studied. Results of the measurements reveal an increase in the aerosol number concentration in the sub-micron and micron size ranges. The increase occurred after a time lag of about 70 min from the beginning of the eclipse. This may be explained in terms of the effect of condensationalgrowth due to increased relative humidity.
4 citations
TL;DR: The period 1850-1910 was a "golden age" in Australian astronomy, with the establishment of professional observatories, substantial growth of popular interest in astronomy, establishment of a network of significant private observatories across the nation, and formation of Australia's earliest astronomical groups and societies as discussed by the authors.
Abstract: The period 1850–1910 was a ”golden age” in Australian astronomy, with the establishment of professional observatories, substantial growth of popular interest in astronomy, establishment of a network of significant private observatories across the nation, and formation of Australia’s earliest astronomical groups and societies.
3 citations
TL;DR: In this article, the geometry governing the radiative decays of solar neutrinos was studied during a solar eclipse and a satellite-based experiment was proposed to improve the sensitivity.
Abstract: Motivated by a pilot experiment conducted by F.Vannucci et al. during a solar eclipse, we work out the geometry governing the radiative decays of solar neutrinos. Surprisingly, although a smaller proportion of the photons can be detected, the case of strongly non-degenerate neutrinos brings better limits in terms of the fundamental couplings. We advocate satellite-based experiments to improve the sensitivity.
2 citations
18 Aug 1998
TL;DR: In this paper, the authors analyzed the observation data of solar UV, visible, infrared and total radiation during the 9 March 1997solar eclipse at Mohe have been analyzed, results are the following: during period of solar eclipse,variation trends of solarUV, visible and infrared were similar, their energydeficits and percentages of energy deficit increased with increasing area of the sun's surface covered by the moon's umbra, and reached the maximum at the maximum of the solar eclipse.
Abstract: The observation data of solar UV, visible, infrared and total radiation during the 9 March 1997solar eclipse at Mohe have been analyzed, results are the following: during period of solar eclipse,variation trends of solar UV, visible, infrared and total radiation were similar, their energydeficits and percentages of energy deficit increased with increasing area of the sun's surfacecovered by the moon's umbra, and reached the maximum at the maximum of the solar eclipse. The energylosses of solar UV, visible, infrared and total radiation in solar eclipse were 0. 09, 0. 55, 0. 72and 1. 28 MJ/m2, respectively. There were still good relationship among solar UV, visible, infraredand total radiation during the solar eclipse.Key Words: Solar Spectral Radiation, Solar Eclipse. 1. Introduction The last total solar eclipse in the 20th century happened in Mohe county, Heilongjiang province,on March 9, 1997. In order to research the variation regularity of solar spectral radiation receivedat the ground during the total solar eclipse, a shortterm observation of 13 days at Mohe countywas carried out.
TL;DR: In this article, the geometry governing the radiative decays of solar neutrinos was studied during a solar eclipse and a satellite-based experiment was proposed to improve the sensitivity.
Journal Article•
Journal Article•
TL;DR: In this article, the authors tried to find the causes of the mistakes and restore their original state so as to use them in the reaserch on history of astronomy and modern sciences.
Abstract: Beginning from Ming Dynasty (1368~ 1644 AD), many ancient astronomical recordswere collected in local chronicles and solar eclipse was one of the main topics. Differingfrom the official records, local records sometimes keep more vivid details of the celestialphenomena, Nevertheless there are much more mistakes in them than in the officialrecords. Of 662 items of local records of solar eclipse in Ming Dynasty, 270 items describelarge eclipse with words such as 'total', 'all stars were seen', 'dark as middle night',These valuable records were collected from hundreds of rare ancient books twenty yearsago in a huge project and have not been formaily published before. Unfortumately most ofthese records can not be identified by modern astronomical computation because of themistakes which came from the process in which the books were produced. ln this paper the270 items of large eclipse records are presented and each one has been examined by textualreaserch and astronomical computation. The authors tried to firld the causes of the mistakes and restore their original state so as to use them in the reaserch on history of astronomy and modern sciences.
Journal Article•
TL;DR: A microclimatological tower of 1.6 m height with six instrumented booms at different heights carrying wind speed, temperature and humidity sensors was set up at Robertsgun 24° 42'N, 83°4'E, 3l2m amsl as mentioned in this paper.
Abstract: A microclimatological tower of 1.6 m height with six instrumented booms at different heights carrying wind speed, temperature and humidity sensors was set up at Robertsgun 24° 42'N, 83°4'E, 3l2m amsl) to study the implication of the total Solar eclipse on the dynamics of Atmospheric Boundary Layer (ABL). Apart from this, the soil temperature and heat flux were also measured during the same time. The observations were taken with a one minute average interval and recorded continuously with the data logger and then transferred to a PC for later use. The data were collected during 2l –26 October 1995. During the eclipse period decrease of surface temperature and soil temperature by 6.2°C and 3.5°C respectively and increase of humidity by nearly 60% were observed. Due to the decrease in velocity fluctuations, the mean wind speed showed the sharp increase compared to other days. The setting of stable atmosphere before the total solar eclipse was observed.
TL;DR: In this article, a summary of recent research on the eclipse records in the Koryo-sa is presented, which is based on a careful examination of the astrological treatise of the Kori-sa.
Abstract: The following is a summary of recent research which I have undertaken on the eclipse records in the Koryo-sa. This work is based on a careful examination of the astrological treatise of the Koryo-sa. I have compared each of the many solar and lunar eclipse accounts with the results of computation and based deductions on these comparisons.
01 Jan 1998
TL;DR: In this paper, the authors report results on solar prominences from their observations of the November 3, 1994 total solar eclipse from the North Chile alteplano, using their transportable camera and telescope, as well as support photographic digitised observations from Putre and Parinacota volcano.
Abstract: We report results on solar prominences from our observations of the November 3, 1994 total solar eclipse from the North Chile alteplano. From the military base at Putre, we used our transportable CCD camera and telescope, as well as support photographic digitised observations from Putre and Parinacota volcano. The variation of density and equivalent temperature were derived in coronal holes (plumes and interplumes) and in equatorial streamers. We obtained images from the inner to the outer corona, as well as low-resolution spectra of prominences and of the inner corona. We present the analysis of images and spectra of prominences in the Balmer, He I and Ca II lines, and in the Thomson scattered continuum.
TL;DR: The Sun is our star The source of light and energy which makes our life possible A source of inspiration for scientists and for artists However, until a few decades ago, we only knew that star through the observations of its yellow/orange visual disk and through the occurrence of rare eclipses, when the Moon covers nearly exactly the Sun's disk and reveals the corona as mentioned in this paper.
Abstract: The Sun is our star The source of light and energy which makes our life possible A source of inspiration for scientists and for artists However, until a few decades ago, we only knew that star through the observations of its yellow/orange visual disk and through the occurrence of a few rare eclipses, when the Moon covers nearly exactly the Sun’s disk and reveals the corona, the spectacular extension of the solar atmosphere into interplanetary space Everything we knew, in particular of the interior of the Sun, was derived from models built from the “observable” quantities: geometrical dimension, mass, brightness, surface temperature, ratio of abundance of helium over hydrogen, etc
TL;DR: An excellent series of images of solar granulation was taken during the partial solar eclipse of 1994 May 10 at the Swedish Vacuum Solar Telescope at Roque de los Muchachos Observatory as discussed by the authors.
Abstract: An excellent series of images of solar granulation was taken during the partial solar eclipse of 1994 May 10 at the Swedish Vacuum Solar Telescope at Roque de los Muchachos Observatory. Making use of the lunar limb profile, images at different heliocentric positions were corrected for instrumental and atmospheric effects. The centre-to-limb variation of the granulation contrast was calculated and compared with previous determinations.