Showing papers on "Solar eclipse published in 2010"

Total solar eclipse observations of hot prominence shrouds

Abstract: Using observations of the corona taken during the total solar eclipses of 2006 March 29 and 2008 August 1 in broadband white light and in narrow bandpass filters centered at Fe X 637.4 nm, Fe XI 789.2 nm, Fe XIII 1074.7 nm, and Fe XIV 530.3 nm, we show that prominences observed off the solar limb are enshrouded in hot plasmas within twisted magnetic structures. These shrouds, which are commonly referred to as cavities in the literature, are clearly distinct from the overlying arch-like structures that form the base of streamers. The existence of these hot shrouds had been predicted by model studies dating back to the early 1970s, with more recent studies implying their association with twisted magnetic flux ropes. The eclipse observations presented here, which cover a temperature range of 0.9 to 2 ×106 K, are the first to resolve the long-standing ambiguity associated with the temperature and magnetic structure of prominence cavities.

Mapping the Distribution of Electron Temperature and Fe Charge States in the Corona with Total Solar Eclipse Observations

Abstract: The inference of electron temperature from the ratio of the intensities of emission lines in the solar corona is valid only when the plasma is collisional. Once collisionless, thermodynamic ionization equilibrium no longer holds, and the inference of an electron temperature and its gradient from such measurements is no longer valid. At the heliocentric distance where the transition from a collision-dominated to a collisionless plasma occurs, the charge states of different elements are established, or frozen-in. These are the charge states which are subsequently measured in interplanetary space. We show in this study how the 2006 March 29 and 2008 August 1 eclipse observations of a number of Fe emission lines yield an empirical value for a distance, which we call Rt , where the emission changes from being collisionally to radiatively dominated. Rt ranges from 1.1 to 2.0 R ☉, depending on the charge state and the underlying coronal density structures. Beyond that distance, the intensity of the emission reflects the distribution of the corresponding Fe ion charge states. These observations thus yield the two-dimensional distribution of electron temperature and charge state measurements in the corona for the first time. The presence of the Fe X 637.4 nm and Fe XI 789.2 nm emission in open magnetic field regions below Rt , such as in coronal holes and the boundaries of streamers, and the absence of Fe XIII 1074.7 nm and Fe XIV 530.3 nm emission there indicate that the sources of the solar wind lie in regions where the electron temperature is less than 1.2 × 106 K. Beyond Rt , the extent of the Fe X [Fe9+] and Fe XI emission [Fe10+], in comparison with Fe XIII [Fe12+] and Fe XIV [Fe13+], matches the dominance of the Fe10+ charge states measured by the Solar Wind Ion Composition Spectrometer, SWICS, on Ulysses, at –43° latitude at 4 AU, in March-April 2006, and Fe9+ and Fe10+ charge states measured by SWICS on the Advanced Composition Explorer, ACE, in the ecliptic plane at 1 AU, at the time of both eclipses. The remarkable correspondence between these two measurements establishes the first direct link between the distribution of charge states in the corona and in interplanetary space.

GPS TEC response to the 22 July 2009 total solar eclipse in East Asia

Abstract: [1] The longest total solar eclipse of this century occurred in East and South Asia on 22 July 2009. The eclipse was accompanied with a medium magnetic storm, whose main phase onset occurred ∼27 min after the passage of the Moon's umbral shadow. Using TEC data from 60 GPS stations, we construct differential TEC maps to investigate the ionosphere response to the solar eclipse in central China in the range of 26°N–36°N, 108°E–118°E (i.e., the magnetic latitude 15°N–25°N). During the eclipse's totality, a “shadow” in the ionosphere shown as TEC depletion area was formed ∼100 km south of the Moon's umbral path with a maximum decrease of 5 TECU. The TEC depletion area moved eastward, following the movement of the totality area with a time lag of ∼10 min. Enhancements of TEC due to the storm are observed after the main phase onset. The relative drop of TEC due to the solar eclipse is evidently larger at lower latitudes than that at higher ones and around noontime than that in the morning. By modeling work, we find that the latitudinal dependence of the TEC response may result from latitudinal variation of magnetic inclination, which influences the diffusion of ionization among different layers. Besides, the local time dependence of TEC response is closely related to the local time variation of background atmosphere density, which affects the electron loss efficiency in the ionosphere.

Response of the equatorial lower ionosphere to the total solar eclipse of 22 July 2009 during sunrise transition period studied using VLF signal

Abstract: [1] Changes in equatorial D-region electron density are studied using subionospherically propagating VLF signal at 18.2 kHz over a distance of 2200 km during the total solar eclipse of 22 July 2009. There are very few studies about the eclipse's effects on the equatorial lower ionosphere in the scientific literature. In the light of that, the objective of the present work is to study the effects of the eclipse on the dynamics of the equatorial lower ionosphere during ionospheric sunrise transition period. In the present case, great circle path between VLF transmitter and receiver falls totally in partial eclipse zone, having a maximum solar obscuration of 90% and an average obscuration of 74%. Results show an average decrease of 3.2 dB in signal strength compared to control days during peak solar obscuration over the path. A comparison with previous studies shows an increase both in lower ionosphere virtual reflection height (H′) and Wait inverse scale height parameter (β); the values estimated are 74.5 km and 0.46 km−1 compared to unperturbed ionosphere values of 71 km and 0.43 km−1, respectively. During maximum eclipse over the path, the model profile shows an average 80% drop in electron density at a height of 71 km at equatorial lower ionosphere. A nonlinear variation of lower ionosphere electron density with solar radiation is found as opposed to the model study proposed by previous workers.

Enhancement and HF Doppler observations of sporadic‐E during the solar eclipse of 22 July 2009

Abstract: [1] The sporadic E (Es) frequently emerging in midlatitude during summer is a very special layer in the ionosphere, and its formation mechanism is different to from that of other layers. The total solar eclipse of 22 July 2009 provided a very unique opportunity to study the relationship of Es and solar radiation. During the solar eclipse day and the days before and after, the vertical incidence ionosonde was located in Wuhan to record the ionograms for this event. Two oblique incidence high-frequency radio systems were used to record the waves from Wuhan to Suzhou and from Wuhan to Huaian. The enhancement of Es during the eclipse period was observed in the vertical and oblique incidence ionograms. The quasi-periodic fluctuations in the critical frequency and Doppler frequency shift curves indicated the possible existence of the gravity waves, which may be responsible for the Es enhancement. However, we find that the enhancement occurred earlier than the appearance of gravity waves and consider that there may be other mechanisms which contribute to the observed enhancement in the ionosphere. A hypothesis is put forward that the cooling effect of the lunar shadow induced powerful airflow from the northern and southern limits of the shadow toward its center, which accelerated the irregularities in Es to produce the large-scale Doppler shift in the reflected waves and form the meridional windshear. Both the windshear and the gravity waves may affect the Es layer and increase the electron concentration. Many observed phenomena are in accordance with this.

Effects of the solar eclipse on 15 January 2010 on the surface O3, NO, NO2, NH3, CO mixing ratio and the meteorological parameters at Thiruvanathapuram, India

Abstract: . In this paper, we present the effect of total solar eclipse on surface O3, NO, NO2, NH3, CO mixing ratio and the meteorological parameters on 15 January 2010 at Thiruvanathapuram, India. On the day of total solar eclipse (i.e., 15 January 2010), the decrease in mixing ratio of surface O3 and NO2 is observed after the beginning of the solar eclipse events (11:15 to 15:30). Decrease in surface O3 may be due to decreased efficiency of the photochemical ozone formation, whereas, mixing ratio of NO and NH3 have been changed following the night time chemistry. Surface O3 reduced to 20.3 ppb after 22 min of full phase of the eclipse. During the solar eclipse period, the ambient temperature and wind speed have decreased, whereas, relative humidity has increased as expected.

Ionospheric and geomagnetic response to the total solar eclipse on 1 August 2008 over Northern Hemisphere

Abstract: [1] The ionospheric and geomagnetic response to the total eclipse of the Sun on 1 August 2008 over Northern Hemisphere has been examined using 14 GPS, three ISR radar, and three magnetometer ground-based stations. Three different approaches were employed to examine the TEC depletion occurrence at the GPS stations: determination of the TEC depletion parameters during the solar eclipse with respect the quiet day TEC variations, comparison of the total TEC (ΣTEC) during the solar eclipse period with respect to quiet day TEC measurements for the same period of time, and determination of the average daily TEC obtained from eight GPS stations and compares the values with the average quiet day TEC at these stations. The GPS observations indicate obvious TEC depression occurrence at all stations with the values was varying between 11% and 40%. The observations show that TEC depression at most GPS stations started on the neck of the first contact of the eclipse followed by deeper negative deviation while the area of optical disk obscured getting larger. Periods of TEC depletion were also observed before the first contact time of solar eclipse and after the fourth contact of solar eclipse due to earlier and later obscuration of the solar corona before and after the eclipse observation time. The incoherent scatter radar observations at Svalbard, Tromso, and Sondrestrom also show clear depletion occurrence in electron density, electron temperature, ion velocity, and plasma cutoff frequency during the solar eclipse passage at these stations. Radar measurements show obvious difference in the ionospheric response between the E and F layers of ionosphere and between ion and electron temperature in the F layer. The geomagnetic field response to the solar eclipse at CBB, RESO, and NUR stations was examined by using two different techniques, first by comparing the daily variations of geomagnetic field during the eclipse period with the variations on the day before and day after the eclipse, and second by determination the Δ magnetic field with respect to the average quiet geomagnetic field. The results show obvious decrease in the total field, X and Z components of geomagnetic field and obvious increase in the Y component at both CBB and RESO stations. The depletion in X, Z, and total field was in the range between 15 and 28 nT while the increase in the Y component was 18–22 nT.

Variations in the amplitude and phase of VLF radiowaves in the ionosphere during the August 1, 2008, solar eclipse

Abstract: Time variations in the amplitude and phase of signals of the Russian telecommunication station (the frequency is 25 kHz) on the Arkhangelsk—Kharkov path with a length of about 1600 km on the day of the August 1, 2008 solar eclipse (SE) and on the adjacent days are analyzed. Two types of effects are detected. An increase of the signal amplitude by approximately 32% in comparison with the background days and the 2.1 μs time shift of the signal during 2—2.5 h is referred to the first type. Changes in the spectral composition of the quasiperiodic disturbances in the ionosphere presented the second type of the effects. For spectral analysis of the quasiperiodic variations in the amplitude and phase of the radio signal, the window Fourier transform, adaptive Fourier transform, and wavelet transformation were applied simultaneously. In the period of SE and after it, oscillations with periods of 10—15 min (according to the amplitude data) and also about 10 and 18 min (according to the phase data) were intensified. Based on radio signal characteristics, the parameters of ionospheric disturbances are estimated.

Wave response of the ionosphere to the partial solar eclipse of August 1, 2008

Abstract: Quasi-periodic variations in the Doppler shift of the HF range frequency at a vertical path and critical frequency of the F 2 layer caused by wave disturbances in the ionosphere on the day of the partial (the magnitude was about 0.42) solar eclipse and on background days are analyzed. For the spectral analysis, the window Fourier transform, adaptive Fourier transform, and wavelet analysis were jointly used. It is shown that on the day of the eclipse and the background day, spectral characteristics of wave disturbances within the 150–200 km height range differed substantially. The changes in the spectral composition began approximately 30–35 min after the solar eclipse beginning and lasted more than 1.5 h.

Solar eclipse effects of 22 July 2009 on Sporadic-E

Abstract: . The total solar eclipse of 22 July 2009, was visible from some regions of China and the intense sporadic-E (Es) that broke out during the solar eclipse period over the eastern China provided a unique chance to study solar eclipse effects on the Es-layer. The ground based high-frequency (HF) vertical-incidence and oblique-incidence backscatter radio systems in Wuhan and an HF oblique receivers located in Suzhou were operated to detect the Es-layer. The vertical, oblique and backscatter ionograms of 22 and 23 July were recorded, processed and analyzed. The analyzing results show that the critical frequency of Es, the hop number and power of the rays transmitted from Wuhan to Suzhou as well as the Doppler frequency shift of the one-hop oblique-incidence waves reflected by the Es-layer all increased during the solar eclipse period. These variations are displayed in the paper and explained to be induced by the wind-field, which is produced by the powerful meridional air flows from the sunshine region to the moon's shadow.

Observations and modeling of the ionospheric behaviors over the east Asia zone during the 22 July 2009 solar eclipse

Abstract: [1] The longest total solar eclipse during the 21st century with a maximum duration of 6 min and 39 s occurred in South and East Asia on 22 July 2009. The TEC data from four GPS stations in the total eclipse region (around 30°N) from 105°E to 135°E are used to study the variation in TEC. Height profiles of electron density from Formosa3/Cosmic satellites are used to study the height dependence of the electron density response. We also modeled the eclipse effects on the ionosphere by an ionospheric model. Both the observations from F3/C and the modeled results show that there is an overall decrease in the electron density below F2 region, with the largest relative decrease occurring at F1 region. The TEC observations show the delay time of the largest TEC decrease at the total eclipse region with regard to the maximum obscuration is less than five minutes and smaller than what is estimated from the time constant of the plasma loss rate at the F2 peak altitude although main contribution to TEC comes from the plasma density in the F2 region. The modeling study shows that, due to the large plasma flux from topside ionosphere to F2 layer, the TEC response around 30°N is mainly due to the electron density response at low altitudes (E and F1 region, 200 km below) where the time delay of electron density response is very short (less than 4 min). Thus the time delay of TEC response would also be short as observed by GPS TEC.

Profiles of temperature responses to the 22 July 2009 total solar eclipse from FORMOSAT‐3/COSMIC constellation

Abstract: [1] Due to the difficulty in making reliable and timely four-dimensional observations of atmospheric temperature in the vicinity of the path of the total solar eclipse, direct measurements of temperature changes from the troposphere to the stratosphere during a total solar eclipse still haven't been reported before. In this work we use profiles of temperature measurements from a constellation of the FORMOSAT-3/COSMIC (FS3/C) LEO satellites to estimate temperature changes during the 22 July 2009 total solar eclipse. The FS3/C data reveals a very important temperature response structure in the vertical. The cooling in the troposphere can be attributed to the reduction in solar heating, which is thermally driven. The warming in the stratosphere, especially for those that occurred between 13 and 23 km altitudes could be dynamically driven, which can be induced by the thermal contraction of the troposphere.

Ionosphere variations at 700 km altitude observed by the DEMETER satellite during the 29 March 2006 solar eclipse

Abstract: We present an experimental and modeling study of the effects of the 29 March 2006 solar eclipse in the topside ionosphere. Measurements of the densities and temperatures of the thermal electrons and ions were provided by instruments aboard the Centre National d'Etudes Spatiales microsatellite DEMETER, which flew over Europe and Africa near the time of maximum solar obscuration. Data from several orbits, either on the same day or on days encompassing the eclipse day, were available to determine a reference state of the ionosphere along the orbit in absence of eclipse. The comparison between this latter and the actual observations along the eclipse orbit reveal a clear thermal effect with a fast drop of about 200 K of the electron and ion temperatures that follows the variations of the solar UV flux in the F region of the ionosphere conjugate to the satellite position. The plasma density decreases by about 30% but with a significant delay and is better correlated with the solar UV flux averaged over the previous 1 to 2 h in the conjugate F region. This delayed and prolonged decrease of density induces an increase of the electron temperature to be higher than the reference ionosphere. We have also performed a modeling of the ionosphere using the SAMI2 code, after having introduced adequate modifications to reproduce fairly realistic eclipse conditions. Applied to the DEMETER conditions of observation, the model reproduces the observations very well. This work shows that the plasma temperature responds very quickly along the magnetic field lines to the variations of the energy available from the photoelectrons while the plasma density variations are controlled by more complex and slower transport processes.

A Comparison of the Red and Green Coronal Line Intensities at the 29 March 2006 and the 1 August 2008 Total Solar Eclipses: Considerations of the Temperature of the Solar Corona

Abstract: During the total solar eclipse at Akademgorodok, Siberia, Russia, on 1 August 2008, we imaged the flash spectrum with a slitless spectrograph. We have spectroscopically determined the duration of totality, the epoch of the second and third contacts and the duration of the flash spectrum. Here we compare the 2008 flash spectra with those that we similarly obtained from the total solar eclipse of 29 March 2006, at Kastellorizo, Greece. Any changes of the intensity of the coronal emission lines, in particularly those of Fe x and Fe xiv, could give us valuable information about the temperature of the corona. The results show that the ionization state of the corona, as manifested especially by the Fe xiv emission line, was much weaker during the 2008 eclipse, indicating that following the long, inactive period during the solar minimum, there was a drop in the overall temperature of the solar corona.

Search for Rapid Changes in the Visible-Light Corona during the 21 June 2001 Total Solar Eclipse

Abstract: Some 8000 images obtained with the Solar Eclipse Coronal Imaging System (SECIS) fast-frame CCD camera instrument located at Lusaka, Zambia, during the total eclipse of 21 June 2001 have been analysed to search for short-period oscillations in intensity that could be a signature of solar coronal heating mechanisms by MHD wave dissipation. Images were taken in white-light and Fe xiv green-line (5303 A) channels over 205 seconds (frame rate 39 s−1), approximately the length of eclipse totality at this location, with a pixel size of four arcseconds square. The data are of considerably better quality than those that we obtained during the 11 August 1999 total eclipse (Rudawy et al.: Astron. Astrophys. 416, 1179, 2004), in that the images are much better exposed and enhancements in the drive system of the heliostat used gave a much improved image stability. Classical Fourier and wavelet techniques have been used to analyse the emission at 29 518 locations, of which 10 714 had emission at reasonably high levels, searching for periodic fluctuations with periods in the range 0.1 – 17 seconds (frequencies 0.06 – 10 Hz). While a number of possible periodicities were apparent in the wavelet analysis, none of the spatially and time-limited periodicities in the local brightness curves was found to be physically important. This implies that the pervasive Alfven wave-like phenomena (Tomczyk et al.: Science317, 1192, 2007) using polarimetric observations with the Coronal Multi-Channel Polarimeter (CoMP) instrument do not give rise to significant oscillatory intensity fluctuations.

Results of VLF campaigns in Summer, Winter and during Solar Eclipse in Indian Subcontinent and Beyond

Abstract: VLF propagation effects are generally understood in terms of the earth‐ionosphere waveguide. However, details of the theory are still incomplete. Particularly important are the newly emerging fields of VLF Astronomy where the ionosphere is treated as a giant detector for extraterrestrial energetic phenomena and the subject of lithosphere‐ionosphere coupling where the the disturbances of this giant detector is influenced by terrestrial events, especially earthquakes and other seismic activities. We review the activities of our group in these fields. In particular, we concentrate on the results of the VLF campaigns we conducted using over a dozen receiving stations in Summer, in Winter and during the Total Solar eclipse in July, 2009. We also discuss briefly the results we obtained in Antarctica and their implications.

Correlated anomalous effects observed during the August 1st 2008 solar eclipse

Abstract: During the solar eclipse of 1 August 2008 three programs of physics observations were independently conducted by teams in Kiev, Ukraine, and Suceava, Romania, separated by about 440 km. The Ukraine team operated five independent miniature torsion balances, one Romania team operated two independent short ball-borne pendulums, and the other Romania team operated a long Foucault-type pendulum. All three teams detected unexplained disturbances, and these disturbances were mutually correlated. The overall pattern of the observations exhibits certain perplexing features.

Nighttime-like quasi periodic echoes induced by a partial solar eclipse

Abstract: [1] The first observations of solar eclipse induced mid-latitude plasma irregularities using the middle and upper atmosphere radar (MU radar) at Shigaraki (34.85°N,136.1°E, 25.0°N geomagnetic) are presented. The observations were done during the partial solar eclipse on 22 July, 2009. The observations show that the sudden withdrawal of solar radiation could deplete the background E-region densities, thereby unmasking the long-lived metallic ions within the strong and patchy Sporadic E-layers. As a result of this, Quasi-Periodic (QP) echoes were generated, which were detected by the MU radar. These echoes resemble the normal post-sunset QP echoes observed over mid-latitudes as revealed by the multi-channel interfereometry imaging. This example shows that over mid-latitudes E-region plasma irregularities can be generated during a partial solar eclipse, revealing a hitherto unobserved aspect of mid-latitude ionospheric responses to eclipses.

Cosmic ray intensity and surface parameters during solar eclipse on 22 July 2009 at Kalyani in West Bengal

Abstract: Cosmic ray (CR) intensity and surface meteorological parameters are measured during solar eclipse (maximum phase 90.2%) on 22 July 2009 at Kalyani in West Bengal. A sudden drop in counts is noted after 51 min 12 sec of the occurrence of the first contact. The counts recover at the termination of the eclipse with a delay time of 2 h. Variation in temperature, relative humidity, tropopause height and tropopause temperature has been examined. Solar geomagnetic parameters revealed peak activity on eclipse day. The reduction in CR intensity caused by local climate change is interpreted though no apparent relation is exhibited between CR intensity and geomagnetic disturbances.

The solar eclipse and associated atmospheric variations observed in South Korea on 22 July 2009

Abstract: A partial solar eclipse occurred in South Korea on 22 July 2009. It started at 09:30 a.m. and lasted until 12:14 LST with coverage of between 76.8% and 93.1% of the sun. The observed atmospheric effects of the eclipse are presented. It was found that from the onset of the eclipse, solar radiation was reduced by as much as 88.1 ∼ 89.9% at the present research centre. Also, during the eclipse, air temperature decreased slightly or remained almost unchanged. After the eclipse, however, it rose by 2.5 to 4.5°C at observed stations. Meanwhile, relative humidity increased and wind speeds were lowered by the eclipse. Ground-level ozone was observed to decrease during the event.

The Effects of Solar Eclipse of August 1, 2008 on Earth’s Atmospheric Parameters

Abstract: Several experiments were undertaken at Kolkata (latitude: 22°34′N, longitude: 88°30′E) on the solar eclipse day of August 1, 2008 to observe the effects of the solar eclipse on Fair Weather Field (FWF) and VLF amplitude and phase. The experimental results presented here show significant deviations of the observed parameters from their normal values, as they are determined by the average of the records obtained on 5 days adjacent to the day of the solar eclipse.

Ozone and NO2 variations measured during the 1 August 2008 solar eclipse above Eureka, Canada with a UV‐visible spectrometer

Abstract: [1] On 1 August 2008, a solar eclipse of 98% totality passed over the Polar Environment Atmospheric Research Laboratory at Eureka, Canada (80.05°N, 86.42°W), which is run by the Canadian Network for the Detection of Atmospheric Change. During the eclipse, a zenith-sky UV-visible spectrometer measured slant column densities (SCDs) and vertical column densities (VCDs) of ozone up to 82% occultation and NO2 up to 96% occultation, beyond which low light intensities and changes in the solar spectrum due to limb darkening compromised data quality. Ozone VCDs during the eclipse remained within natural variability, and this study is inconclusive regarding ozone oscillations due to limited temporal resolution and measurement errors toward eclipse maximum. Measured NO2 SCDs increased and decreased symmetrically around the eclipse maximum. NO2 SCDs were also calculated using a photochemical box model and a one-dimensional radiative transfer model. The modeled ratio of eclipse day SCDs to the previous day's SCDs was compared to the measurements. They agreed within error bars leading up to maximum occultation, but the model ratio was systematically larger than the measured ratio for the second half of the eclipse, perhaps due to changing cloud conditions throughout the eclipse. The measured NO2 SCD ratio of 1.84−0.43+0.12 at 96% totality is larger than observed in past studies and agrees with modeled ratio of 1.91. Therefore our current understanding of stratospheric photochemistry is sufficient to predict the evolution of NOx chemistry through a solar eclipse.

Measurements of atmospheric electrical conductivities during the total solar eclipse of 22 July, 2009

Abstract: The effect of total solar eclipse on atmospheric conductivities has been studied. Continuous measurements of both types of positive and negative electrical conductivities and some meteorological parameters in conjunction with the total solar eclipse of 22 July, 2009 were made from 21 to 23 July, 2009 at Roorkee (29°52′ N, 77°53′ E, 275 m above sea level). Roorkee observed 90% maximum obscurity of eclipse since it was close to the path of totality. The event started from 05:28 AM IST and ended at 07:42 AM IST with the total eclipse at 06:30 AM IST. Considerable increase of both positive and negative conductivities were recorded during the eclipse with respect to those made on any other day. Increase in relative humidity and decrease in temperature were also observed during the period of eclipse.

Effects of the solar eclipse of August 1, 2008, on the earth’s lower atmosphere

Abstract: The paper presents results of optical observations and analysis of dynamics of effects on the earth’s lower atmosphere of the partial solar eclipse (of magnitude 42%) of August 1, 2008, near Kharkov This is compared with the effects induced by the partial solar eclipses on August 11, 1999, and October 3, 2005 All three eclipses occurred around midday The standard deviation of the solar-limb displacement σ S during the eclipses on October 3, 2005, August 1, 2008, and August 11, 1999, was established to decrease by 013, 030, and 068″ at the maximum of the solar obscuration function 013, 031, and 073, respectively, so that the temperature drop in the earth’s lower atmosphere t a was 13, 20, and 73 K The time lags of decreases of σ S and t a was found to be 15 and 5 minutes

A solar eclipse seen from the High Arctic during the period of midnight sun: effects on the local meteorology

Abstract: The solar eclipse on 1 August 2008 was studied on Svalbard (93% totality), an archipelago in the High Arctic, where midnight sun had been present for several months. Simultaneous observations over land and over a large fjord showed that the eclipse triggered downslope winds in the valleys surrounding the fjord, thereby creating low-level clouds over the water. These clouds were later advected in over land and created a fog that lasted for 3 days, grounding all air traffic to and from Svalbard. The atmospheric response was otherwise much slower and weaker over water than over land. Over land, the wind speed decreased, the atmospheric stability changed from unstable to stable and the air temperature sank by 0.3–1.5°C, while over the fjord no clear minima in these parameters could be found.