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Solar eclipse

About: Solar eclipse is a research topic. Over the lifetime, 2737 publications have been published within this topic receiving 22625 citations.


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TL;DR: The Meteorological Radiation Model (MRM) as discussed by the authors has been developed in the last half of the 20th century to generate artificial solar radiation series or calculate the availability of solar energy at a place.
Abstract: Various solar broadband models have been developed in the last half of the 20th century. The driving demand has been the estimation of available solar energy at different locations on earth for various applications. The motivation for such developments, though, has been the ample lack of solar radiation measurements at global scale. Therefore, the main goal of such codes is to generate artificial solar radiation series or calculate the availability of solar energy at a place. One of the broadband models to be developed in the late 80's was the Meteorological Radiation Model (MRM). The main advantage of MRM over other similar models was its simplicity in acquiring and using the necessary input data, i.e. air temperature, relative humidity, barometric pressure and sunshine duration from any of the many meteorological stations. The present study describes briefly the various steps (versions) of MRM and in greater detail the latest version 5. To show the flexibility and great performance of the MRM, a harsh test of the code under the (almost total) solar eclipse conditions of 29 March 2006 over Athens was performed and comparison of its results with real measurements was made. From this hard comparison it is shown that the MRM can simulate solar radiation during a solar eclipse event as effectively as on a typical day. Because of the main interest in solar energy applications about the total radiation component, MRM focuses on that. For this component, the RMSE and MBE statistical estimators during this study were found to be 7.64% and −1.67% on 29 March as compared to the respective 5.30% and +2.04% for 28 March. This efficiency of MRM even during an eclipse makes the model promising for easy handling of typical situations with even better results.

55 citations

Journal ArticleDOI
TL;DR: In this article, the spatial pattern of midlatitude ionospheric response to a total solar eclipse was studied using a model for ionosphere-plasmasphere coupling, and it was shown that changes in the spatial distribution of electron density along the HF ray paths during the eclipse give rise to variations of Doppler frequency shift with amplitudes of about 1 Hz and a duration of about 120 min.
Abstract: The total solar eclipse of March 9, 1997, was visible from some regions of China, Mongolia, and East Siberia during 0045–0130 UT. The eclipse coincided with a relatively long geomagnetically quiet period. During the total solar eclipse, the observations included oblique-incidence ionograms recording; also measurement the total electron content along specified directions to the visible Global Positioning System satellites and the Doppler sounding on various HF ray paths over the region under consideration were carried out. This paper presents results derived from studying the spatial pattern of midlatitude ionospheric response to this eclipse on the basis of a numerical simulations. Calculations have been executed using a model for ionosphere-plasmasphere coupling. Comparison of model results with data of all measurements showed a good qualitative and quantitative agreement. It is shown that by and large the behavior of the ionosphere during the eclipse manifests itself as a short-lasting (∼l-hour) rearrangement to nighttime conditions with the ion flow directed downward from the plasmasphere, as a rise of the F2 layer maximum by about 20 km, and as a twofold increase in electron density at the height of the maximum during the eclipse's totality phase. The electron temperature decreases by 200–400 K, while the ion temperature drops only slightly. It is found that changes in the spatial distribution of electron density along the HF ray paths during the eclipse give rise to variations of Doppler frequency shift with amplitudes of about 1 Hz and a duration of about 120 min. The findings reported in this paper do not validate the hypothesis that solar eclipses generate atmospheric gravity waves and associated traveling ionospheric disturbances.

55 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compared diagnostics for temperature and density within large-scale structures of the inner corona based on cospatial and cotemporal spectrophotometric observations made at the time of the total solar eclipse of 1988 March 17/18.
Abstract: This paper explores and compares diagnostics for temperature and density within large-scale structures of the inner corona based on cospatial and cotemporal spectrophotometric observations made at the time of the total solar eclipse of 1988 March 17/18. In the analysis a determination of plasma temperature T can be derived unambiguously from the intensity ratios Fe XIV/XUV or Fe XIV/Fe X since all the emission lines come from the ionized state of Fe and the ratios are only weakly dependent on density. These temperatures and the densities found in well-defined large-scale coronal structures are discussed. The emission-line temperature is found to be high (local maxima) in the coronal structures with enhanced white-light emission and associated with new cycle high-latitude magnetic fields separated from the old cycle polar field of opposite polarity. Also the average of the ratio of scale-height temperature/temperature over the entire range of position angle is roughly unity although the ratio is higher than unity (1.3-1.6) in the three most prominent streamers.

55 citations

Journal ArticleDOI
TL;DR: The National Center for Atmospheric Research (NCAR) thermospheric general circulation model (TGCM) was used to calculate the time-dependent response of the winds, temperature, and the mass mixing ratios of the major constituents throughout the thermosphere as mentioned in this paper.
Abstract: The National Center for Atmospheric Research (NCAR) thermospheric general circulation model (TGCM) is used to calculate the time-dependent thermospheric response to the May 30, 1984, annular solar eclipse. The path of maximum obscurity begins at sunrise in the Pacific Ocean near 2°N and 135°W. It moves northeastward, passing across central Mexico, the eastern United States, and then the Atlantic before ending near 28°N and 4°E in Algeria. The area of the partial shadow is relatively large, and the total solar flux incident on the dayside of the earth is decreased by about 6% during the eclipse. The TGCM calculates the time-dependent response of the winds, temperature, and the mass mixing ratios of the major constituents throughout the thermosphere. Perturbations follow the path of the annular eclipse, with maximum deviations occurring near 1700 UT at about 300 km for the temperature and at higher altitudes for the winds and composition. The perturbation winds converge from all directions toward the shadow at speeds reaching 75 m s−1 in the upper thermosphere. The maximum temperature anomaly (−55 K) and vertical wind anomaly (−7 m s−1) occur near the center of the shadow. At a constant altitude of 300 km, both the N2 density and the O density decrease by about 10% and 6%, respectively. The path of maximum obscuration passes within 3° of latitude of the incoherent scatter radar at Millstone Hill, Massachusetts (42.6°N, 71.5°W). The station experiences a maximum solar obscuration of 86% at 1700 UT (1200 LT). A time-dependent one-dimensional numerical model of the ionosphere that uses the TGCM-calculated winds, temperature, and composition at Millstone Hill is used to calculate the electron and ion densities and temperatures and the densities of the odd-nitrogen species NO, N(4S), and N(²D) during the eclipse. The calculated electron density decreases by about factors of 2 in the F region, 4 in the F1 region, and 3 in the E region compared to a similar control run without an eclipse. The F1 region emerges during the eclipse with an increase in the NO+/O+ ratio. The calculated electron temperature decreases by 460 K during the eclipse but then increases 200 K following the eclipse because of the intense solar heating in a region of reduced electron densities. The calculated ion temperature generally follows the changes in neutral temperature. The calculated thermospheric and ionospheric responses agree well with measurements made by the Millstone Hill incoherent scatter radar.

54 citations

Journal ArticleDOI
TL;DR: In this article, the LaCoste-Romberg D gravimeter was used to measure the variations of gravity during a total solar eclipse to investigate the effect of a solar eclipse on the gravitational field.
Abstract: The variations of gravity were measured with a high precision LaCoste-Romberg D gravimeter during a total solar eclipse to investigate the effect of a solar eclipse on the gravitational field. The observed anomaly $(7.0\ifmmode\pm\else\textpm\fi{}2.7)$$\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ ${\mathrm{m}/\mathrm{s}}^{2}$during the eclipse implies that there may be a shielding property of gravitation.

54 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202354
2022136
202191
202084
201992
2018104