Showing papers on "Solar eclipse published in 2013"

Where Is That Moon, Anyway? The Problem of Interpreting Historical Solar Eclipse Observations

Abstract: This chapter contains sections titled: The Problem, The Nineteenth Century, The Twentieth Century, Conclusion

Ionospheric response to total solar eclipse of 22 July 2009 in different Indian regions

Abstract: . The variability of ionospheric response to the total solar eclipse of 22 July 2009 has been studied analyzing the GPS data recorded at the four Indian low-latitude stations Varanasi (100% obscuration), Kanpur (95% obscuration), Hyderabad (84% obscuration) and Bangalore (72% obscuration). The retrieved ionospheric vertical total electron content (VTEC) shows a significant reduction (reflected by all PRNs (satellites) at all stations) with a maximum of 48% at Varanasi (PRN 14), which decreases to 30% at Bangalore (PRN 14). Data from PRN 31 show a maximum of 54% at Kanpur and 26% at Hyderabad. The maximum decrement in VTEC occurs some time (2–15 min) after the maximum obscuration. The reduction in VTEC compared to the quiet mean VTEC depends on latitude as well as longitude, which also depends on the location of the satellite with respect to the solar eclipse path. The amount of reduction in VTEC decreases as the present obscuration decreases, which is directly related to the electron production by the photoionization process. The analysis of electron density height profile derived from the COSMIC (Constellation Observing System for Meteorology, Ionosphere & Climate) satellite over the Indian region shows significant reduction from 100 km altitude up to 800 km altitude with a maximum of 48% at 360 km altitude. The oscillatory nature in total electron content data at all stations is observed with different wave periods lying between 40 and 120 min, which are attributed to gravity wave effects generated in the lower atmosphere during the total solar eclipse.

Solar eclipse of August 1, 2008, above Kharkov: 1. Results of incoherent scatter observations

Abstract: The observation results of the effects in the geospace plasma during a partially (magnitude ∼0.42) solar eclipse are presented. The experimental data were obtained with an incoherent scatter radar of the Institute of the Ionosphere (near Kharkov). During the eclipse, the density at the F2 layer maximum decreased by 32%, the foF2 critical frequency decreased by 17.5%, and the altitude of the F2 layer maximum increased insignificantly. At altitudes of 290–680 km, the electron density decreased by ∼25%. During the eclipse, the electron and ion temperature decreased by 70–180 and 0–140 K, respectively, at altitudes of 190–490 km. Near the eclipse main phase, the plasma velocity vertical component decreased by 10–45 m/s at altitudes of 200–470 km, respectively. At the time of the eclipse main phase, the hydrogen ion fractional density increased by 50% as compared to the reference day at altitudes of 450–650 km.

Nighttime ionospheric enhancements induced by the occurrence of an evening solar eclipse

Abstract: [1] The solar eclipse on 15 January 2010 traversed Asia and completed its travel on the Shandong Peninsula in China at sunset Two vertical incidence ionosondes at Wuhan and Beijing and the oblique incidence ionosonde network in North China were implemented to record the ionospheric response to the solar eclipse Following the initial electron density decrease caused by the eclipse, the ionosphere was characterized by a strong premidnight enhancement, and a subsequent ionospheric decay, and a ~10 h later postmidnight enhancement Neither geomagnetic disturbance occurred during the eclipse day nor did obvious nighttime peak appear for the 10 day mean of the F2-layer critical frequency (foF2) The electron density profilogram of the Beijing ionosonde indicates that the two enhancements were the result of the plasma flux downward from the top ionosphere, possibly due to the steep decrease of the ionospheric electron density and plasma temperature during the solar eclipse The two-dimensional differential foF2 maps present the regional variations of the nighttime electron density peaks and decay Both the pre- and postmidnight enhancements initially appeared in a belt almost in parallel with the eclipse track and then drifted southward The different magnitudes of greatest eclipse in the umbra and outside tend to account for the different occurrence times of the plasma flux The ionospheric decay following the premidnight enhancement is also considered as a consequence of the eclipse shade

Solar eclipse of August 1, 2008, over Kharkov: 3. calculation results and discussion

Abstract: The calculation results of parameters of thermal and dynamical processes in the near-Earth plasma during the partial solar eclipse of August 1, 2008, over Kharkov are presented. The calculations showed that during the eclipse there occurred a decrease in the neutral temperature by approximately 17–40 K within the height range 250–350 km, respectively. At heights of 210–580 km, the eclipse resulted in an increase in the density, total plasma flux, and the flux of particles by tens of percentage points due to ambipolar diffusion. The paper presents the results of a comparative analysis of the effects in the ionospheric plasma during the partial eclipses over Kharkov of August 11, 1999; May 31, 2003; October 3, 2005; March 29, 2006; and August 1, 2008. General regularities in eclipse effects are noted.

Surface Pressure Fluctuations Produced by the Total Solar Eclipse of 1 August 2008

Abstract: During a solar eclipse, the Moon's shadow progressively occults a part of the Earth from the solar flux. This induces a cooling in the atmospheric layers that usually absorb the solar radiation. Since the eclipse shadow travels within the atmosphere at supersonic velocity, this cooling generates a planetary-scale bow-wave of internal gravity waves. The purpose of this article is to estimate the surface pressure fluctuations produced by the passage of the 1 August 2008 total solar eclipse and to compare these pressure fluctuations with those recorded by a temporary network of microbarographs and by the infrasound stations of the International Monitoring System. The surface pressure fluctuations expected at all the measurement sites are estimated using a linear spectral numerical model. It is shown that the cooling of both the ozonosphere and the troposphere can produce detectable pressure fluctuations at the ground surface but that the tropospheric cooling is likely to be the predominant source. Since the expected eclipse signals are in a frequency range that is highly perturbed by atmospheric tides and meteorological phenomena, the pressure fluctuations produced by these synoptic disturbances are characterized and removed from the recorded signals. Low-frequency gravity waves starting just after the passage of the eclipse are then brought to light at most measurement sites. The time-frequency characteristics of these waves are similar to those obtained from the model, which strongly suggests that these waves were produced by the passage of the 1 August 2008 solar eclipse.

Physical processes in the middle ionosphere accompanying the solar eclipse of January 4, 2011, in Kharkov

Abstract: Aperiodic and quasi-periodic variations in the critical frequency of the F2 layer and Doppler frequency shift of radiowaves at vertical paths on the day of a partial (the magnitude was ∼0.78) solar eclipse and on background days are analyzed. According to the experiment, the relative decrease in the electron concentration was 0.41 (0.46 according to calculations) and 0.50 (0.53 according to calculations) in the E region and in the lower part of the F region of the ionosphere. At a height of the main maximum of the electron concentration, the relative decrease in the electron concentration was 0.52 (0.51 according to calculations). It is shown that on the day of the eclipse and on the background day, the characteristics of wave disturbances within the height range 160–240 km were substantially different. Changes in the spectral composition began 30 min after the eclipse occurrence and, depending on the period, lasted from 2 to 4 h. The calculation results of the main parameters of the medium and signal correspond to the observational results.

Solar eclipse of August 1, 2008, above Kharkov: 2. Observation results of wave disturbances in the ionosphere

Abstract: Quasi-periodic variations in the power of incoherent scattered signals, caused by wave disturbances of the electron concentration in the ionosphere, are analyzed for the day of a partial solar eclipse and for a background day. The windowed and adaptive Fourier transforms and the wavelet transform are used for spectral analysis. The spectral parameters of the wave disturbances at altitudes of 100–500 km in the 10–120 min period range differed significantly on the day of the solar eclipse and on the background day. Variations in the spectrum began near the onset of the phase of maximum disk occultation and continued no less than 2 h. The amplitude of time variations N was 2 × 109–4 × 1010 m−3, and the relative amplitude was 0.10–0.15. Wave disturbances have been compared for five solar eclipses; the comparison shows a noticeable variation in the spectrum of the wave disturbances during these events.

Study of Atmospheric Boundary Layer Thermodynamics During Total Solar Eclipses

Abstract: The results of remote sensing temperature profiles measurements within a 0-600-m altitude range and total water content measurements during total (Kislovodsk, 2006; Novosibirsk, 2008) and partial (Moscow, 2011) solar eclipses, using microwave radiometers are presented. Initially, continuous data on temperature profiles are obtained at different altitudes before, during, and after total solar eclipses, using two single channel elevation scanning microwave temperature profilers. Terrestrial consequences of solar eclipses (especially total ones) are quite noticeable and important. Solar eclipses support unique, specific conditions, which gives the opportunity for various meteorological research. The most important indicator of thermodynamic processes occurring during solar eclipses is air temperature at different altitudes in the atmospheric boundary layer (ABL). The ABL temperature depends, in general, on the flux of solar radiation and some features of the ground (albedo, absorptivity, and emissivity) and the air (humidity). Temperature profile measurements are accompanied by solar radiation (with net-radiometer) and total water vapor (with microwave radiometers) measurements. The observation results of this paper will contribute detailed model calculations for clarifying meteorological effects of solar eclipses. Observations of the next total solar eclipse over Russia (August 12, 2026) can be used to verify our observational results.

On the combination of imaging-polarimetry with spectropolarimetry of upper solar atmospheres during solar eclipses

Abstract: We present results from imaging polarimetry (IP) of upper solar atmospheres during a total solar eclipse on 2012 November 13 and spectropolarimetry of an annular solar eclipse on 2010 January 15. This combination of techniques provides both the synoptic spatial distribution of polarization above the solar limb and spectral information on the physical mechanism producing the polarization. Using these techniques together we demonstrate that even in the transition region, the linear polarization increases with height and can exceed 20%. IP shows a relatively smooth background distribution in terms of the amplitude and direction modified by solar structures above the limb. A map of a new quantity that reflects direction departure from the background polarization supplies an effective technique to improve the contrast of this fine structure. Spectral polarimetry shows that the relative contribution to the integrated polarization over the observed passband from the spectral lines decreases with height while the contribution from the continuum increases as a general trend. We conclude that both imaging and spectral polarimetry obtained simultaneously over matched spatial and spectral domains will be fruitful for future eclipse observations.

Eclipses Observed by Large Yield RAdiometer (LYRA) – A Sensitive Tool to Test Models for the Solar Irradiance

Abstract: We analyze the light curves of the recent solar eclipses measured by the Herzberg channel (200 – 220 nm) of the Large Yield RAdiometer (LYRA) onboard Project for OnBoard Autonomy (PROBA2). The measurements allow us to accurately retrieve the center-to-limb variations (CLV) of the solar brightness. The formation height of the radiation depends on the observing angle, so the examination of the CLV provide information about a broad range of heights in the solar atmosphere. We employ the 1D NLTE radiative transfer COde for Solar Irradiance (COSI) to model the measured light curves and corresponding CLV dependencies. The modeling is used to test and constrain the existing 1D models of the solar atmosphere, e.g. the temperature structure of the photosphere and the treatment of the pseudo-continuum opacities in the Herzberg continuum range. We show that COSI can accurately reproduce not only the irradiance from the entire solar disk, but also the measured CLV. Hence it can be used as a reliable tool for modeling the variability of the spectral solar irradiance.

Ionospheric effects on the F region during the sunrise for the annular solar eclipse over Taiwan on 21 May 2012

Abstract: . On 21 May 2012 (20:56, Universal Time; UT, on 20 May), an annular solar eclipse occurred, beginning at sunrise over southeast China and moving through Japan, sweeping across the northern Pacific Ocean, and completing its passage over the western United States at sunset on 20 May 2012 (02:49 UT, 21 May). We investigated the eclipse area in Taiwan, using an ionosonde and global positioning system (GPS) satellite measurements. The measurements of foF2, hmF2, bottomside scale height around the peak height (Hm), and slab thickness (B0) were collected at the ionosonde station at Chung-Li Observatory. In addition, we calculated the total electron content (TEC) to study the differences inside and outside the eclipse area, using 3 receivers located at Marzhu (denoted as MATZ), Hsinchu (TNML), and Henchun (HENC). The results showed that the foF2 values gradually decreased when the annularity began and reached a minimum level of approximately 2.0 MHz at 06:30 LT. The hmF2 immediately decreased and then increased during the annular eclipse period. The TEC variations also appeared to deplete in the path of the eclipse and opposite the outside passing area. Further, the rate of change of the TEC values (dTEC / dt measured for 15 min) was examined to study the wave-like fluctuations. The scale height near the F2 layer peak height (Hm) also decreased and then increased during the eclipse period. To address the effects of the annular eclipse in the topside and bottomside ionosphere, this study provides a discussion of the variations between the topside and bottomside ionospheric parameters during the eclipse period.

Daytime E-Region Irregularities During the 22 July 2009 Solar Eclipse over Chung-Li (24.9°N, 121.2°E), a Moderate Mid-Latitude Station

Abstract: The 22 July 2009 solar eclipse with an obscuration of > 83% at Chung-Li (24.9°N, 121.2°E, Dip 35°N) in Taiwan during noon hours has provided a unique opportunity for us to examine its impact on E-region irregularities which were observed simultaneously by the 52 MHz coherent radar and a co-located ionosonde. Significant observations revealed that the daytime E-region strong backscatter echoes at multiple heights and a sudden intensification of the weak sporadic E-layer during the 22 July 2009 solar eclipse. These results follow the research findings of Patra et al. (2009). As the incident solar radiation suddenly blocked by intruding Moon during solar eclipse events that would generally create night-like ionospheric conditions, it is surmised that the E-region irregularities were indeed induced by the eclipse associated effects. The induced effects resulted in faster recombination of molecular ions, generation of gravity waves and electric fields that could have created a conducive environment to excite plasma irregularities through a gradient-drift instability mechanism. The vertical shears of radar Doppler velocity and the peak radar backscatter at the node of Doppler velocity shear, as resolved by the coherent scatter radar with interferometer technique, were possibly due to the upward propagating gravity waves and wave-induced polarization electric fields. The present observational results should not only be highly useful to ascertain plausible mechanisms responsible for nighttime E-region irregularities, but also provided evidence that a solar eclipse could generate E-region plasma irregularities over temperate mid-latitudes for the first time.

Annular and Total Solar Eclipses of 2010

Abstract: While most NASA eclipse bulletins cover a single eclipse, this publication presents predictions for two solar eclipses during 2010. This has required a different organization of the material into the following sections. Section 1 -- Eclipse Predictions: The section consists of a general discussion about the eclipse path maps, Besselian elements, shadow contacts, eclipse path tables, local circumstances tables, and the lunar limb profile. Section 2 -- Annular Solar Eclipse of 2010 Ja n 15: The section covers predictions and weather prospects for the annular eclipse. Section 3 -- Total Solar Eclipse of 2010 Jul 11: The se ction covers predictions and weather prospects for the total eclipse. Section 4 -- Observing Eclipses: The section provides information on eye safety, solar filters, eclipse photography, and making contact timings from the path limits. Section 5 -- Eclipse Resources: The final section contains a number of resources including information on the IAU Working Group on Eclipses, the Solar Eclipse Mailing List, the NASA eclipse bulletins on the Internet, Web sites for the two 2010 eclipses, and a summary identifying the algorithms, ephemerides, and paramete rs used in the eclipse predictions.

Link between Allais effect and General Relativity’s residual Arc during solar Eclipse

Abstract: The purpose of this article is to establish a relation between two gravitational anomalies: one that has attracted part of the scientific community, the Allais effect that occurs during solar eclipse; the other, noticed but forgotten by the whole scientific community, the General Relativity’s residual arc of the curvature of rays of light in the solar gravitational field during the same eclipse. There is a systematically observed deflection about 10 percent larger than the theoretical value of General Relativity, which coincides with the «eclipse effect» found by Maurice Allais, thrown aside because it upsets the established truths. These corresponding anomalies were never explained by any theories and turn out to be new gravitational physics.

Highlighting the History of Japanese Radio Astronomy. 2: Koichi Shimoda and the 1948 Solar Eclipse

Abstract: Just two years after Dicke carried out the first radio observations of a solar eclipse, a young Japanese physics graduate, Koichi Shimoda, attempted to observe 3,000 MHz emission during the 9 May 1948 partial solar eclipse. In so doing he unwittingly became the ‘founding father’ of Japanese radio astronomy. In this paper as our mark of respect for him, we list Shimoda as the lead author of the paper so that his observations can finally be placed on record for the international radio astronomical community.

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

Abstract: 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, 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.

The Torsind—A Device Based on a New Principle for Non-Conventional Astronomical Observations

Abstract: The description of a new device which is an improved version of the classic torsion balance is given. The device, which is the so-called “torsind”, seemed to be very sensitive to solar/lunar eclipses, and a Venus transit. It even responded to a solar eclipse when installed underground. The results of the most well-documented cases are described.

Eclipse on the Coral Sea: Cycle 24 Ascending

Abstract: A total solar eclipse is the most spectacular and awe-inspiring astronomical phenomenon most people will ever see in their lifetimes. Even hardened solar scientists draw inspiration from it. The eclipse with 2 minutes totality in the early morning of 14 November 2012 (local time) drew over 120 solar researchers (and untold thousands of the general public) to the small and picturesque resort town of Palm Cove just north of Cairns in tropical north Queensland, Australia, and they were rewarded when the clouds parted just before totality to reveal a stunning solar display. The eclipse was also the catalyst for an unusually broad and exciting conference held in Palm Cove over the week 12--16 November. Eclipse on the Coral Sea: Cycle 24 Ascending served as GONG 2012, LWS/SDO-5, and SOHO 27, indicating how widely it drew on the various sub-communities within solar physics. Indeed, as we neared the end of the ascending phase of the peculiar Solar Cycle 24, it was the perfect time to bring the whole community together to discuss our Sun's errant recent behaviour, especially as Cycle 24 is the first to be fully observed by the Solar Dynamics Observatory (SDO). The whole-Sun perspective was a driving theme of the conference, with the cycle probed from interior (helioseismology), to atmosphere (the various lines observed by the Atmospheric Imaging Assemble (AIA) aboard SDO, the several instruments on Hinode, and other modern observatories), and beyond (CMEs etc). The quality of the presentations was exceptional, and the many speakers are to be commended for pitching their talks to the broad community present. These proceedings draw from the invited and contributed oral presentations and the posters exhibited in Palm Cove. They give an (incomplete) snapshot of the meeting, illustrating its broad vistas. The published contributions are organized along the lines of the conference sessions, as set out in the Contents, leading off with a provocative view of Cycle 24 thus far from Sarbani Basu. Other invited papers presented here include an appreciation of Hinode's view of solar activity as the cycle rises by Toshifumi Shimizu; a first taxonomy of magnetic tornadoes and chromospheric swirls by Sven Wedemeyer {\it et al}; an analysis of Hinode/EIS observations of transient heating events; a timely re-examination of solar dynamo theory by Paul Charbonneau; an exciting teaser for the solar potential of the Murchison Widefield Array now operating in Western Australia by Steven Tingay {\it et al}; an overview and critique of the state of nonlinear force-free magnetic field extrapolation theory and practice by Mike Wheatland and Stuart Gilchrist; and a masterful review of atmospheric MHD wave coupling to the Sun's internal p-mode oscillations by Elena Khomenko and Irantzu Calvo Santamaria. The many contributed papers published here are no less exciting. All papers have been refereed to a high standard. The editors thank all the referees, drawn both from conference attendees and the wider community, who have taken their tasks very seriously and provided very detailed and helpful reports. Nearly all contributions have been substantially improved by the process. We must also thank our financial sponsors. Both the Global Oscillations Network Group (GONG) and LWS/SDO were generous in their support, as were the School of Mathematical Sciences and the Monash Centre for Astrophysics (MoCA) at Monash University, Melbourne, and the Centre for Astronomy at James Cook University, Townsville. The Local Organizing Committee and the many students who assisted before and during the conference also deserve high praise for facilitating such a memorable meeting. Paul Cally, Robert Erdelyi and Aimee Norton

GPS derived ionospheric TEC response to annular solar eclipse over Indian region on 15 January 2010

Abstract: The dual frequency Global Positioning System (GPS) observation data from International GNSS Services (IGS) stations established at Bangalore (IISC) and Hyderabad (HYDE) are processed to estimate the change in ionospheric total electron content (TEC) in response to the annular solar eclipse of 15 January 2010. This event was unique since it took place during solar minimum. It was a geomagnetically quiet period and the eclipse phase coincided with the peak ionization time at the Indian equatorial and low latitudes. The path of the solar obscuration during the eclipse passed through the Indian Ocean, touching the southern part of India. The sudden collapse of the TEC curve at Bangalore and Hyderabad indicates the effect of of blocked solar radiation on decayed electron content in ionosphere over the region. The magnitude of the depletion in ionospheric TEC over both stations are compared with mean diurnal ionospheric TEC of five quietest days of the month to investigate the eclipse effect on electron density of ionosphere over the stations.

Total Solar Eclipse of 2001 June 21

Abstract: On 2001 June 21, a total eclipse of the Sun will be visible from within a narrow corridor which traverses the Southern Hemisphere. The path of the Moon's umbral shadow begins in the South Atlantic, crosses southern Africa and Madagascar, and ends at sunset in the Indian Ocean. A partial eclipse will be seen within the much broader path of the Moon's penumbral shadow, which includes eastern South America and the southern two thirds of Africa. Detailed predictions for this event are presented and include besselian elements, geographic coordinates of the path of totality, physical ephemeris of the umbra, topocentric limb profile corrections, local circumstances for approximately 350 cities, maps of the eclipse path, weather prospects, the lunar limb profile and the sky during totality. Tips and suggestions are also given on how to safely view and photograph the eclipse.

Sky Brightness Condition During Total Solar Eclipse on July 22, 2009

Abstract: A total solar eclipse is suspected to have influence to the physical parameter of an environment area particularly the brightness of the sky and other environmental parameters such as temperature and humidity. The brightness of the sky, temperature and humidity were measured during the total solar eclipse on 22 July nd 2009 by using the SQM (Sky Quality Meter) and hygrometer. The results obtained show changes in sky brightness, temperature and humidity during the totality.

Atmospheric electric parameters and micrometeorological processes during the solar eclipse on 15 January 2010

Abstract: [1] Indian scientists got the unique opportunity to study the near-Earth environment during a long annular solar eclipse at the end of the last long deep solar minimum, on 15 January 2010. Continuous high time resolution records of the atmospheric electric parameters and meteorological parameters were made at Tirunelveli (8.07°N, 77.08°E, 35 m Above Mean Sea Level (AMSL) and Braemore Hill (8.41°N, 76.59°E, 460 m AMSL) stations where the eclipse was during 11:07:57–15:06:52 IST with maximum obscuration (~90%) at 13:17:09 Indian Standard Time (IST). The recorded values of the parameters show marked deviations from those normally observed on control fair-weather days. The ambient electric field underwent a large drop by up to 65% during the eclipse, and potential gradient showed epochs of enhancements during and after the eclipse until postsunset. The data also seem to reveal the long lasting paradox of conductivity enhancement during eclipse, which may be due to the eclipse induced upsurge of low winds or waves that brings high density of free space charges embedded in air parcels.