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Electron heating rate and ion chemistry in thermosphere above Wallops Island during solar eclipse of March 7 1970
Results of soundings with a series of five pitot probes launched in conjunction with the solar eclipse of Mar. 7, 1970. Three soundings were programmed to occur at 40, 80, and 100% obscuration of the sun (at 100 km) during a 42-min period. The remaining two soundings were made 24 hr before and after the eclipse. The five soundings yielded neutral particle pressure, temperature, and density profiles over the altitude regime from 30 to 125 km. Below 95 km, the three density profiles resulting from the eclipse day launches had an average deviation of less than 1.5%. Above 95 km, density changes of up to 20% were observed. Such changes in density are comparable in magnitude to those normally observed over a period of several hours. On Mar. 10, 1971, three additional pitot probes were launched at times identical to those of the 1970 eclipse day. Comparison of the two sets of data should provide for a more objective analysis regarding atmospheric response to solar input.
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Rocket sounding measurements of ionospheric D region electron density profile during 20 May 1966 solar eclipse, discussing D region ionization source
Thermospheric electron heating rate and ion chemistry above Wallops Island during 7 March 1970 solar eclipse, measuring ion composition and concentration
Global Ionospheric Specification (GIS) is based on the Gauss–Markov Kalman filter to assimilate the slant total electron content (TEC) observed from ground-based GPS receivers and space-based radio occultation instrumentations in order to reconstruct three-dimensional (3D) ionospheric electron density structure, and it can remotely sense and monitor the weather condition in space. In this study, five minutes of high temporal resolution GIS is implemented in order to reconstruct the 3D electron density structure on the 21 August 2017 total solar eclipse and analyze the variations induced by the moon’s shadow. To obtain more information of the ionosphere, from the extend 2200 GPS stations on the continental United States, are added for assimilation. The results show the ionosphere peak height (hmF2) uplift was 30–50 km altitude in latitude 25–40°N, and that the electron density depletion at higher altitudes (400 km) has a more noticeable time delay than at low altitudes (200 km), especially in low-latitude regions.
Photoelectric observations of short term light variations (shadow bands) at the 16 Feb. 1980 total solar eclipse have been made using a set of spatially separated PIN diodes. Light variations in a bandpass of 1-500 Hz were detected during the half-minutes preceding and following the total phase. Fourier analysis of the noise spectrum of the variations reveals a sharp drop-off for frequencies above 50 Hz and an overall spectrum quite similar to previously reported power spectra of stellar scintillation. This is consistent with an atmospheric origin for the shadow bands. Cross-correlations between the detector outputs are low, suggesting a short persistence time for the turbulent elements causing the patterns.
Observations made during the interval March 1-31, 1988, are presented which were designed to provide a synoptic context in which data from the March 18, 1988, total solar eclipse can be interpreted. Daily observations made with the Mark III K-coronameter and the H-alpha prominence monitor at the Mauna Loa Solar Observatory, along with photographic records of the Sun in H-alpha from the flare patrol at Mees Solar Observatory on Haleakala, Maui, are included. Observations of the longitudinal component of the photospheric magnetic field made at Mees Solar Observatory were also gathered around the period of the eclipse. Together with the white-light image of the corona at the eclipse, these coronal and magnetic field observations assembled into synoptic maps for this epoch, are presented. On the basis of these observations, an interpretation of the global density distribution of the corona at the time of the eclipse is constructed.
Ionospheric Lyman alpha intensities and electron and positive ion densities during solar eclipse of 20 May 1966, discussing recombination model
Local measurements of stratospheric NO and O3 mixing ratios and air temperature were made during the total solar eclipse of 26 February 1979. The instrumentation was carried aboard a U-2 aircraft flown at an altitude of 19.8 km in the region near 47 deg N, 112 deg W. Eclipse maximum occurred approximately in the middle of the 2-3/4-hr measurement period. The NO mixing ratio was reduced at least a factor of 25 at the maximum of the eclipse. The decrease and recovery of NO during the passage of the Moon's shadow over the measurement region follows approximately the predictions of two independent models. No change was observed in either the O3 mixing ratio or the air temperature that could be attributed to the eclipse.
On 30 May 1984, the Millstone Hill incoherent scatter radar was operated to gather data on the effects of the annular solar eclipse on the structure and dynamics of the ionosphere and thermosphere. The eclipse path was about 3 deg. south of Millstone which experienced a maximum obscuration of 86% at about 1705 UT. Both the zenith steerable antennas at Millstone were used in the experiment to collect data on the temporal evolution of the eclipse effects. This experiment represented the first opportunity at Millstone to collect data during an eclipse in the absence of a major magnetospheric disturbance which had previously made the unravelling of eclipse effects difficult. In addition, the configuration of the experiment and analysis of the data included a detailed examination of the effects on the neutral atmosphere. A major catalyst for this study was the opportunity to compare the results with the predictions made from the Thermospheric General Circulation Model (TGCM) at NCAR, as a calibration point for the model. The Arecibo and Sondrestrom radars also participated as part of a radar chain experiment. The analysis of the data from these stations is in progress; the initial results from Millstone Hill are presented.
Brightness distribution of local source over sunspot group during solar eclipse
Radio spectrum analysis of two active regions based on Laplace transform and brightness temperatures from Nov. 12, 1966 solar eclipse data
Solar inner corona forbidden emission lines and continuum enhancement during 30 May 1965 eclipse as function of heliocentric position angle
Results of measurements made with a retarding potential analyzer on a Nike-Tomahawk rocket during the totality of the solar eclipse, showing definite evidence for the existence of photoelectrons from the conjugate hemisphere. Photoelectrons are observed in the altitude range from 120 to 260 km. The observed flux in the energy range from 2 to 30 eV is relatively constant above about 200 km, but decreased below that altitude. The flux of 5-eV energy electrons above 200 km altitude is about 10 to the 7th power electrons/cm/sec/eV. Higher-energy electrons were also observed, and it is possible that the energy content of these observed fluxes of conjugate-point photoelectrons is sufficient to maintain the observed electron densities and temperatures during the total eclipse.
We describe the use of a three-dimensional MHD model to predict the s tructure of the corona prior to the total solar eclipse of March 29, 2006. The calculation uses the observed photospheric radial magnetic f ield as a boundary condition. We use a new version of our model that has an improved description of energy transport in the corona. The mo del allows us to predict the emission of X-ray and EUV radiation in t he corona. We compare the predicted polarization brightness in the co rona with four observations of the eclipse from Greece, Egypt, and Li bya, and we demonstrate that the model accurately predicts the largescale structure of the corona. We also compare X-ray emission from the model with GOES/SXI images.
August 21, 2017 provided a unique opportunity to investigate the effects of the total solar eclipse on high frequency (HF) radio propagation and ionospheric variability. In Marshall Space Flight Center's partnership with the US Space and Rocket Center (USSRC) and Austin Peay State University (APSU), we engaged students and citizen scientists in an investigation of the eclipse effects on the mid-latitude ionosphere. Activities included implementing and configuring software, monitoring the HF Amateur Radio frequency bands and collecting radio transmission data on days before, the day of, and days after the eclipse to build a continuous record of changing propagation conditions as the moon's shadow marched across the United States. Post-eclipse radio propagation analysis provided insights into ionospheric variability due to the eclipse. We report on results, interpretation, and conclusions of these investigations.