Total Solar Eclipse Of July Research Articles

Changes in meteorological parameters during the total solar eclipse of 2 July 2019 in La Serena, Chile

The first report on the changes in meteorological parameters during the total solar eclipse of July 2, 2019, in La Serena (Chile), is presented. The event could be observed from morning time on the east of New Zealand, in the South Pacific Ocean, to sunset time in Chile. Several meteorological properties such as global radiation Rg, net radiation Rn, reflected radiation Rr (in Wm–2/min), air temperature (TA in °C), relative humidity (RH in %), wind speed amplitude (WS in ms–1), and wind speed direction (WD in degrees), were recorded with La Serena weather station SER (29.827°S, 71.261°W, 28 masl) at 1‑minute time resolution. Importantly, SER was located at 40 km from the axis of the umbra that covered 201 km of width, where it reached 100% darkness at a magnitude of 1.009 during a clear-sky day. Under these auspicious conditions, we observed a rate of changes in the drop of the radiation components of 3.1, 2.4, and 0.5 (Wm–2/min) for Rg, Rn, and Rr, respectively, with a 100% reduction in the components of surface solar radiation (0 Wm–2) during totality. In addition, all components showed a ~34% energy loss during the eclipse in comparison with the day before the event. Also, the rate of changes of –3.3 °C in TA, +11% in RH, –1.11 ms–1 in WS, and 180° to 340° for WD in total synchrony with the passing of the moon in front of the sun, reaching respective peaks at ~5 min lag with respect to totality. Thus, our results show a progressive change in all meteorological parameters in total synchrony with the eclipse’s phases caused by the passing of the moon in front of the sun.

Detection of stratospheric gravity waves induced by the total solar eclipse of July 2, 2019

Atmospheric gravity waves generated by an eclipse were first proposed in 1970. Despite numerous efforts since, there has been no definitive evidence for eclipse generated gravity waves in the lower to middle atmosphere. Measuring wave characteristics produced by a definite forcing event such as an eclipse provides crucial knowledge for developing more accurate physical descriptions of gravity waves. These waves are fundamental to the transport of energy and momentum throughout the atmosphere and their parameterization or simulation in numerical models provides increased accuracy to forecasts. Here, we present the findings from a radiosonde field campaign carried out during the total solar eclipse of July 2, 2019 aimed at detecting eclipse-driven gravity waves in the stratosphere. This eclipse was the source of three stratospheric gravity waves. The first wave (eclipse wave #1) was detected 156 min after totality and the other two waves were detected 53 and 62 min after totality (eclipse waves #2 and #3 respectively) using balloon-borne radiosondes. Our results demonstrate both the importance of field campaign design and the limitations of currently accepted balloon-borne analysis techniques for the detection of stratospheric gravity waves.

Ionospheric monitoring with the Chilean GPS eyeball during the South American total solar eclipse on 2nd July 2019

The impact of total solar eclipse of July 2, 2019 on the Ionosphere is studied using 24 Chilean GPS stations north–south of the totality path. The total solar eclipse passed through Coquimbo region from ~ 16:38 CLT (~ 20:38 UTC) to ~ 16:40 CLT (~ 20:40 UTC) and maximum eclipse was observed ~ 16:39 CLT (~ 20:39 UTC). The total electron content (TEC) derived from GPS signals shows peculiar features. At the totality stations TEC variations are small (~ 0.39 TECu), but it shows significant decrease (maximum ~ 2.24 TECu) for stations located south and increase (maximum ~ 3.89 TECu) for the stations located north of totality of the surface. The wavelet analysis of VTEC timeseries shows the presence of strong atmospheric gravity waves (AGWs) of duration ~ 30 to 60 min at the stations located north of totality. Thus, the results suggest an interplay between eclipse effect on the ionosphere plasma density and eclipse generated AGWs induced plasma density perturbation provided the peculiar features.

On the use of Very Low Frequency transmitter data for remote sensing of atmospheric gravity and planetary waves

Continuous ground-based monitoring of Very Low Frequency (VLF) transmitter signals is an efficient remote sensing tool for studying of the lower ionosphere (60–90km). Here, we present the use of VLF radio data to study short-period (∼min–hrs) atmospheric gravity waves and long-period (∼days) planetary waves. We analyse VLF data from several receiving stations obtained by ICSP-VLF network during the total solar eclipse of July, 2009 to show the existence of short-period atmospheric gravity waves. We find dominant wave periods range from 10min to 1h around the time of maximum eclipse phase which could be associated with atmospheric gravity waves excited due to the eclipse. We also analyse VLF amplitude data of 2007 received at ICSP, Kolkata from VTX (18.2kHz) transmitter for planetary wave-type oscillations in the mesosphere–lower ionosphere system. Fourier and wavelet analysis show presence of periodic structures with periodicity in the range of 5–27days. We compare VLF planetary spectrum with spectrum obtained from total column density of Ozone and mesospheric average temperature data which may indicate vertical coupling between the stratosphere and ionosphere in winter to early spring time.

The response of sporadic E-layer to the total solar eclipse of July 22, 2009 over the equatorial ionization anomaly region of the Indian zone

The digital ionosonde located in Bhopal (23.2°N,77.2°E), India has been used to investigate the responses of the Es layer in the equatorial ionization anomaly (EIA) crest to the total solar eclipse (TSE) of July 22, 2009. Results show the presence of intense Es layer during and after the eclipse period. The gravity waves induced by the solar eclipse propagated upward in the Es layer and produced the periodic disturbance. The results of the wavelet analysis display the presence of dominant oscillation of about 24–32, 16–20 and 8min. The appearance of intense sporadic-E concomitantly with the signatures of gravity wave suggests that the wind shear introduced by the solar eclipse induced gravity wave might be the plausible mechanism behind the intensification of Es-layer ionization.

Prominence-cavity regions observed in 2010 eclipse flash spectra and SWAP images

Images from the SWAP (Proba 2 mission) taken in the Fe IX/X coronal line emission are compared to simultaneous slitless flash spectra taken during the total solar eclipse of July, 11th 2010. Many faint low excitation emission lines together with the HeI and the HeII Paschen α (P α ) chromospheric lines are recorded in the regions of limb prominences observed in space. We consider a deep flash spectrum obtained by summing 80 individual spectra to show the intensity modulations of the continuum between HeI and HeII lines. Intensity depressions are observed around the prominences in both eclipse and SWAP images. The prominence cavities are interpreted as a relative depression of plasma density produced inside the corona surrounding the prominences, and some evidence of intense heating occuring in the region around the prominence is discussed.

Study on the ionospheric TEC variations during the total solar eclipse of July 22, 2009

利用中国区域内五个GPS台站(一个台站处于日全食区域、四个台站处于日偏食区域)观测数据, 研究2009年7月22日日全食期间电离层总电子含量(TEC)的变化, 结果表明, 日全食期间, 电离层TEC值经历了下降和恢复的过程, 最小TEC相对于最大食偏的时间延迟约为1～10min; 台站测得最小TEC的星下点(IPP)越靠近日全食带TEC下降量越大, 在日食期间武汉站(114.35°E, 30.53°N) TEC相对于各参考日期的TEC, 其平均下降量最大, 达到4.58TECU.

Polar plumes observed at the total solar eclipse in 2009

During the total solar eclipse of July 22, 2009, we carried out a white-light observation in Anji, Zhejiang, China. The aim was to observe the polar plumes (PPs) with high spatial and temporal resolutions in white-light. With the observational data, we investigate the properties and evolution of the PPs and compare them with those of the low-latitude plumes (LPs). We find that both the PPs and the LPs have comparable lengths and widths, and the mean length and width are 300 Mm and 16 Mm, respectively. The average inclination angle (13 degree) of the PPs is smaller than that (32 degree) of the LPs. Generally, the plumes which are closer to the coronal hole center are more vertical. We trace the PPs and the LPs in the sequence of images and find that none of them disappears and no new one is created. Additionally, neither plasma outflow nor transverse oscillation is observed. These imply that the evolution process of plumes is much longer than the timescale of eclipse.

Reply to the comments of Le et al. (2011) on the paper “Total solar eclipse of July 22, 2009: Its impact on the total electron content and ionospheric electron density in the Indian Zone” by Sharma et al. (2010)

This short note is a reply to the comments by Le et al. (accepted for publication) on the paper by Sharma et al. (2010) that is concerned with the eclipse time observation of ionospheric TEC and electron density.

Comment on the paper “Total solar eclipse of July 22, 2009: Its impact on the total electron content and ionospheric electron density in the Indian zone” by Sharma et al.

By analyzing COSMIC data, Sharma et al. (2010) found more than 50% reduction in electron density during a solar eclipse at the F2-layer and above, with the peak of ∼70% at 370 km. So great eclipse effect on topside ionosphere was very abnormal and much different from previous studies. However, by comparing the cosmic data with IRI results, we find that the abnormal reduction comes mainly from the significant local time variation at sunrise, not from the eclipse effect. Furthermore, we simulated the eclipse effect by using a theoretical model to confirm our analysis.

Total solar eclipse of July 22, 2009: Its impact on the total electron content and ionospheric electron density in the Indian zone

The longest total solar eclipse during the 21st century occurred in South and East Asia on July 22, 2009. Ionospheric response to this rare total solar eclipse which was observed right from the time of sunrise in the Indian zone, has been studied in terms of the total electron content (TEC) obtained from three global positioning system (GPS) receivers located at Udaipur, Hyderabad and Bengaluru, and electron density obtained using space based GPS-Radio Occultation technique. The study reveals significant reductions in the electron density and TEC that persisted up to 2 h past the last contact even during early morning eclipse. These observations imply that during the early morning eclipse, the production and loss of ionization dominate over the plasma transport processes.

Radial velocity discriminated coronal photometric measurements at the July 11, 1991 total eclipse

The results from a set of 12 solar corona radial velocity measurements in the 400–440 nm spectral band during the total solar eclipse of July 11, 1991 are reported. The measurements show that the orbital motion of the F-corona material near the sun in the ecliptic plane is consistent with Keplerian motion and predominantly, but not exclusively, prograde, as is usually assumed. This work demonstrates a method of using the measured radial velocities to sort out the relative amounts of K-corona, near-earth F-corona, near-solar F-corona, and scattered light in each measurement for each observation point W and E of the sun between 2.5 R o(solar radii) and 5 R o along the celestial equator and at three points north of the sun. The near-solar F-corona component is quite weak, contributing only 7–14% of the total signal in each case. The stronger diffraction component from near-earth F-corona is estimated to have been produced by particles with radii of about 11μ. In contrast, the scattered light component appears as strong zero-velocity features dominating all the measurements. The measurements W and E of the sun and near the ecliptic plane also show evidence of a red-shift velocity of at least 330 km s −1, suggestive of a high-speed dust outflow from the sun.

The chromospheric D3helium emission observed during the total solar eclipse of July 31, 1981

Abstract The digitized images of 350 eclipse chromospheric spectra obtained with a special automatic photometer have been used to construct the image of the D 3 He I chromosphere over the range of 36°N–42°S in latitude. The chromospheric emission comes from two very irregular bands with peaks of intensities at heights of 1100–1700 km for the bands with the dominant emission, and at a height of around 300 km for the lower bands. The distribution of the surface brightness averaged over all measured latitudes (36°N–42°S) versus height also reveals two peaks. The energy emitted by the upper layer is determined to be seven times larger than that emitted by the lower one. The chromospheric D 3 emission is well correlated with the emission of the green corona (503.3 nm) at low heights. The correlation disappears at heights of more than 1500 km. The chromosphere above active regions and spots is lower. It is supposed that such behavior is caused by large-scale magnetic fields of the Sun and by structural elements, such as spicules and fibrils.

Paraconical pendulum as a detector of gravitational effects during solar eclipses (processing data and results)

A statistical analysis of data collected during observation of a total solar eclipse of July 11, 1991 at Mexico City is presented. The variation of the velocity of the azimuth of the major axis of the pendulum's oscillation ellipse during the eclipse is determined and the sudden deviation of the azimuth of the plane of swinging at the start of the eclipse is calculated.

The Structure of the White-Light Corona at the 1991 Eclipse

The total solar eclipse of July 11, 1991 was observed from “La Matanza”, Baja California Sur, México, only 5 km south of the center line of totality, with several small instruments intended to obtain images of the corona during totality, and using a range of exposure times which allowed us to detect both the inner and outer corona. Relations between large and fine scale structures of the corona, the photospheric and chromospheric activity, and the presence of coronal holes are presented.

Air temperature and wind changes in Costa Rica during the total solar eclipse of July 11, 1991

Air temperature and wind measurements on the surface and in the free atmosphere taken during the total solar eclipse of July 11, 1991, are analyzed. Surface air temperature decreased significantly, 2 to 5 °C in general, with the lowest values occurring 10 to 30 minutes after totality. In some places, surface wind speed decreased gradually during the eclipse, as a result of the decrease of air temperature and temperature gradients. In other places, it increased due to local atmospheric conditions. A radiosonde launched at 13:26 LT (local time) appeared to have been affected by the moon's shadow at about 13 km height. At this altitude temperature was relatively lower than usual and the balloon carrying the radiosonde experienced an upward acceleration. Also at this altitude wind direction changed and wind speed decreased

Variation of the geomagnetic field in Costa Rica during the total solar eclipse of July 11, 1991

Ground measurements of the geomagnetic field, during the total solar eclipse of July 11, 1991, were carried out at three sites in Costa Rica located within the eclipse's path of totality. Near totality, there was a significant change in the total intensity,F. Its normal decrease in the afternoon hours was interrupted during a period of about 45 min, in whichF varied very little. This was due mainly to a small variation in horizontal intensity,H, during such a period. The departure ofF from normal lasted about 100 min; its maximum departure was near 10 nT and occurred about 38 min after totality, The declination,D, also experienced a small change (about 2.3 min) during the total period of the eclipse. The vertical intensity,Z, and the inclination,I, did not show significant changes.

Changes in solar irradiance and atmospheric turbidity in Costa Rica during the total solar eclipse of July 11, 1991

Solar global radiation was measured in several places in Costa Rica during the total solar eclipse that occurred on July 11, 1991. In two of these places, Puntarenas and Santa Cruz, measurements in the ultraviolet range (295–385 nm) were also taken. In Santa Cruz, a normal incidence pyrheliometer with Schott filters OG530 and RG630 was used to measure direct solar radiation in its whole range, and in the 530–2800 nm and 630–2800 wavebands respectively. Global radiation, and consequently direct, diffuse and irradiance in any of the wavebands considered, decreased gradually as the sun was being eclipsed and reached zero during the totality, then increased to their normal values. Data registered in Santa Cruz were used to determine Angstrom's atmospheric turbidity parametersα andβ. Computations show that between 13:00 and 14:30 LT (local time),α decreased andβ increased significantly. This indicates that atmospheric turbidity was high and large particles were more abundant than small ones. The size of hygroscopic particles increased during the eclipse when temperature decreased and relative humidity increased in a comparatively short time.

Fluctuations in column ozone during the total solar eclipse of July 11, 1991

A statistical analysis of total column ozone observations during the total eclipse of July 11, 1991, disclosed a series of fluctuations in the ozonosphere following totality. The principle fluctuation, which began 700 seconds after third contact, has an unsmoothed, peak‐to‐peak amplitude of 5 m‐atm‐cm. This amounts to 1.7% of the total ozone column 2000 seconds after third contact. This fluctuation was preceded by one and followed by two fluctuations with reduced amplitude.

Solar chromospheric modeling based on submillimeter limb brightness profile

A method of modeling the solar chromosphere is developed, based on submillimeter continuum observations of the solar limb. Submillimeter radiation from the solar limb emanates from the chromosphere in local thermodynamic equilibrium, making it an important chromospheric diagnostic. Also, the use of high-resolution limb profiles allows for atmospheric modeling independent of gravitational hydrostatic equilibrium. The chromospheric model is constructed to match high-resolution solar limb profiles at 30, 50, 100, and 200 microns, determined by an occultation of the solar limb observed from the Kuiper Airborne Observatory during the total solar eclipse of July 31, 1981. This matching is achieved by 'stretching' the solar model atmosphere of Vernazza, Avrett, and Loesser (1981) vertically out of hydrostatic equilibrium, while maintainingn its vertical temperature-optical depth profile.