scholarly journals Attenuation of global ultraviolet and visible irradiance over Greece during the total solar eclipse of 29 March 2006

2007 ◽  
Vol 7 (23) ◽  
pp. 5959-5969 ◽  
Author(s):  
A. Kazantzidis ◽  
A. F. Bais ◽  
C. Emde ◽  
S. Kazadzis ◽  
C. S. Zerefos
Keyword(s):  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Model Calculations ◽  
Visible Part ◽  
Comparison Results ◽  
Close Proximity ◽  
Limb Darkening ◽  
First Time ◽  
D Model ◽  
Greek Island

Abstract. The variability of ultraviolet and photosynthetically active radiation (PAR) during the total solar eclipse of 29 March 2006 was examined in this study. The measurements from NILU-UV multichannel radiometers at 7 stations of the Greek UV Network were used, where the maximum eclipse percentage ranged from 73.1% to 94.8%. In addition, an extra instrument was established at a remote Greek island, Kastelorizo, which was within the Moon's umbral shadow. The reduction of irradiance at 305 and 312 nm relative to non-eclipse conditions at all sites was almost 1.5 times more than the corresponding decrease in the UVA and visible part of the spectrum and reached 98% for eclipse percentage equal to 94%. The availability of several instruments in close proximity to the path of the umbral shadow provided a challenging test for the models. The measured changes in UV and visible irradiance were compared with 1-D model calculations accounting for the limb darkening effect. The agreement between measurements and modeled values at all sites is within 3% for eclipse percentages of less than 30% and becomes worse as the eclipse progresses. The 1-D model reproduced the spectral effect of the eclipse in UVA and PAR wavelength regions within 3% for eclipse percentages up to 50%, but only the half of the observed change was captured as the eclipse progressed. At three sites, where the eclipse maximum was more than 94%, the measured irradiance at 305 nm for eclipse percentages of more than 85% decreased with slower rates than for longer wavelengths. As a result, the total ozone values, derived from the 305/320 nm ratios, apparently decreased significantly for high eclipse percentages. The effect is similar at all three sites, but the interpretation of this observation remains a challenge. Comparison results with 3-D model calculations shortly before, during and shortly after totality were performed for the first time and revealed an agreement with measurements within 20% in the UV-A region. However, the modeled estimates of irradiance at 312 nm are three times lower than measured values.

scholarly journals Attenuation of global ultraviolet and visible irradiance over Greece during the total solar eclipse of 29 March 2006

2007 ◽  
Vol 7 (5) ◽  
pp. 13475-13501 ◽  
Author(s):  
A. Kazantzidis ◽  
A. F. Bais ◽  
C. Emde ◽  
S. Kazadzis ◽  
C. S. Zerefos
Keyword(s):  
Solar Eclipse ◽  
Total Ozone ◽  
Total Solar Eclipse ◽  
Spectral Ratios ◽  
Model Calculations ◽  
Active Radiation ◽  
Comparison Results ◽  
Limb Darkening ◽  
D Model ◽  
Greek Island

Abstract. The variability of ultraviolet and photosynthetically active radiation during the total solar eclipse of 29 March 2006 was examined in this study. The measurements from NILU-UV multichannel actinometers at 7 stations of the Greek UV Network were used, where the maximum eclipse percentage ranged from 73.1% to 94.8%. In addition, an extra instrument was established at a remote Greek island, Kastelorizo, which was within the Moon's umbral shadow. The measured changes in UV and visible irradiance were compared with 1-D model calculations (accounting for the limb darkening effect) and differences up 30% were observed for the lower UV wavelengths at high eclipse percentages. The spectral ratios between wavelengths was generally reproduced by the 1-D model, expect for 305 nm, where the irradiance at eclipse percentages of more than 85% decreased with slower rates than for longer wavelengths. As a result, the total ozone, derived from the 305/320 nm ratio, apparently decreased significantly for high eclipse percentages. Comparison results with 3-D model calculations approaching and during totality revealed an agreement with measurements in the UV-A region.

scholarly journals Effects of total solar eclipse of 29 March 2006 on surface radiation

2007 ◽  
Vol 7 (3) ◽  
pp. 9235-9258 ◽  
Author(s):  
S. Kazadzis ◽  
A. Bais ◽  
M. Blumthaler ◽  
A. Webb ◽  
N. Kouremeti ◽  
...  
Keyword(s):  
Solar Eclipse ◽  
Total Ozone ◽  
Diffuse Radiation ◽  
Total Solar Eclipse ◽  
Surface Radiation ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Visible Part ◽  
Planck’S Law ◽  
Limb Darkening

Abstract. Solar irradiance spectral measurements were performed during a total solar eclipse. The spectral effect of the limb darkening to the global, direct irradiance and actinic flux measurements was investigated. This effect leads to wavelength dependent changes in the measured solar spectra showing a much more pronounced decrease in the radiation at the lower wavelengths. Radiative transfer model results were used for the computation of a correction for the total ozone measurements due to the limb darkening. This correction was found too small to explain the large decrease in total ozone column derived from the standard Brewer measurements, which is an artifact in the measured irradiance due to the increasing contribution of diffuse radiation against the decreasing direct irradiance caused by the eclipse. Calculations of the Extraterrestrial spectrum and the effective sun's temperatures, as measured from ground based direct irradiance measurements, showed an artificial change in the calculations of both quantities due to the fact that radiation coming from the visible part of the sun during the eclipse phases differs from the back body radiation described by the Planck's law.

scholarly journals The effects of a solar eclipse on photo-oxidants in different areas of China

2011 ◽  
Vol 11 (15) ◽  
pp. 8075-8085 ◽  
Author(s):  
J.-B. Wu ◽  
Z. F. Wang ◽  
W. Zhang ◽  
H. B. Dong ◽  
X. L. Pan ◽  
...  
Keyword(s):  
Solar Eclipse ◽  
Atmospheric Chemistry ◽  
Surface Ozone ◽  
Total Solar Eclipse ◽  
Atmospheric Pollutants ◽  
Chemical Parameters ◽  
Model Calculations ◽  
Meteorological Observations ◽  
Limb Darkening ◽  
The Impact

Abstract. This study investigates the effects of the total solar eclipse of 22 July 2009 on surface ozone and other photo-oxidants over China. A box model was used to study the sensitivity of ozone to the limb darkening effect during an eclipse event, and to show that the impact on ozone is small (less than 0.5 %). In addition, the regional model WRF-Chem was applied to study the effects of the eclipse on meteorological and chemical parameters, focusing on different regions in China. Chemical and meteorological observations were used to validate the model and to show that it can capture the effects of the total solar eclipse well. Model calculations show distinct differences in the spatial distributions of meteorological and chemical parameters with and without the eclipse. The maximum impacts of the eclipse occur over the area of totality, where there is a decrease in surface temperature of 1.5 °C and decrease in wind speed of 1 m s−1. The maximum impacts on atmospheric pollutants occur over parts of north and east China where emissions are greater, with an increase of 5 ppbv in NO2 and 25 ppbv in CO and a decrease of 10 ppbv in O3 and 4 ppbv in NO. This study also demonstrates the effects of the solar eclipse on surface photo-oxidants in different parts of China. Although the sun was obscured to a smaller extent in polluted areas than in clean areas, the impacts of the eclipse in polluted areas are greater and last longer than they do in clean areas. In contrast, the change in radical concentrations (OH, HO2 and NO3) in clean areas is much larger than in polluted areas mainly because of the limited source of radicals in these areas. The change in radical concentrations during the eclipse reveals that nighttime chemistry dominates in both clean and polluted areas. As solar eclipses provide a natural opportunity to test more thoroughly our understanding of atmospheric chemistry, especially that governed by photolysis, a comprehensive experimental campaign during a future solar eclipse is highly desirable.

scholarly journals Effects of total solar eclipse of 29 March 2006 on surface radiation

2007 ◽  
Vol 7 (22) ◽  
pp. 5775-5783 ◽  
Author(s):  
S. Kazadzis ◽  
A. Bais ◽  
M. Blumthaler ◽  
A. Webb ◽  
N. Kouremeti ◽  
...  
Keyword(s):  
Solar Eclipse ◽  
Total Ozone ◽  
Diffuse Radiation ◽  
Black Body ◽  
Black Body Radiation ◽  
Total Solar Eclipse ◽  
Surface Radiation ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Limb Darkening

Abstract. Solar irradiance spectral measurements were performed during a total solar eclipse. The spectral effect of the limb darkening to the global, direct irradiance and actinic flux measurements was investigated. This effect leads to wavelength dependent changes in the measured solar spectra showing a much more pronounced decrease in the radiation at the lower wavelengths. Radiative transfer model results were used for the computation of a correction for the total ozone measurements due to the limb darkening. This correction was found too small to explain the large decrease in total ozone column derived from the standard Brewer measurements, which is an artifact in the measured irradiance due to the increasing contribution of diffuse radiation against the decreasing direct irradiance caused by the eclipse. Calculations of the Extraterrestrial spectrum and the effective sun's temperatures, as measured from ground based direct irradiance measurements, showed an artificial change in the calculations of both quantities due to the fact that radiation coming from the visible part of the sun during the eclipse phases differs from the black body radiation described by the Planck's law.

scholarly journals Mapping prominence plasma parameters from eclipse observations

2013 ◽  
Vol 8 (S300) ◽  
pp. 420-421
Author(s):  
Sonja Jejčič ◽  
Petr Heinzel ◽  
Maciej Zapiór ◽  
Miloslav Druckmüller ◽  
Stanislav Gunár ◽  
...  
Keyword(s):  
Visible Light ◽  
Electron Density ◽  
Solar Eclipse ◽  
Light Emission ◽  
Total Solar Eclipse ◽  
Quiescent Prominence ◽  
Plasma Parameters ◽  
Eclipse Observations ◽  
First Time ◽  
Visible Light Emission

AbstractUsing the eclipse observations, we construct the maps of quiescent prominence temperatures, electron densities, pressures and geometrical thicknesses. For this we use the RGB signal of prominence visible-light emission detected during the total solar eclipse on August 1, 2008 in Mongolia, and quasi-simultaneous Hα spectra taken at Ondřejov observatory. The method of disentangling the electron density and effective geometrical thickness was described by Jejčič & Heinzel (2009) and is used here for the first time to analyse the spatial variations of various prominence parameters.

scholarly journals Surface Radiation during the Total Solar Eclipse over Ny-Ålesund, Svalbard, on 20 March 2015

2016 ◽  
Author(s):  
M. Maturilli ◽  
C. Ritter
Keyword(s):  
Solar Eclipse ◽  
Meteorological Data ◽  
High Arctic ◽  
Total Solar Eclipse ◽  
Surface Radiation ◽  
Test Case ◽  
Data Set ◽  
Radiation Data ◽  
Exchange Processes ◽  
First Time

Abstract. On 20 March 2015, a total solar eclipse occurred over Ny-Ålesund (78.9° N, 11.9° E), Svalbard, in the high Arctic. It has been the first time that the surface radiation components during the totality of a solar eclipse have been measured by a Baseline Surface Radiation Network (BSRN) station. With the Ny-Ålesund long term radiation data set as background (available at http://dx.doi.org/10.1594/PANGAEA.150000), we here present the peculiarities of the radiation components and basic meteorology observed during the eclipse event. The supplementary data set contains the basic BSRN radiation and surface meteorological data in 1-minute resolution for March 2015, and is available at http://dx.doi.org/10.1594/PANGAEA.854326. The eclipse radiation data will be a useful auxiliary data set for further studies on micro-meteorological surface-atmosphere exchange processes in the Svalbard environment, and may serve as a test case for radiative transfer studies.

scholarly journals A study of a solar eclipse using a photocell

2004 ◽  
Vol 26 (4) ◽  
pp. 395-399 ◽  
Author(s):  
J.A. Liendo ◽  
G.H. Chacín
Keyword(s):  
Solar Cell ◽  
Light Intensity ◽  
Solar Eclipse ◽  
Solar Disk ◽  
Mathematical Expression ◽  
Total Solar Eclipse ◽  
Detector Response ◽  
Measured Intensity ◽  
Limb Darkening ◽  
Corrected Intensity

In this work we measured light intensity as a function of time during a total solar eclipse using a solar cell. The measured intensity was corrected for the detector response and compared with a mathematical expression that represents the uncovered apparent area of the solar disk as a function of time. By no means, this corrected intensity is linearly related to the uncovered area, this being due to effects such as the solar corona luminosity, the limb darkening and light scattered in the atmosphere. Estimates of the fraction of light that causes this deviation from linearity are given.

scholarly journals Surface radiation during the total solar eclipse over Ny-Ålesund, Svalbard, on 20 March 2015

2016 ◽  
Vol 8 (1) ◽  
pp. 159-164 ◽  
Author(s):  
Marion Maturilli ◽  
Christoph Ritter
Keyword(s):  
Solar Eclipse ◽  
Meteorological Data ◽  
High Arctic ◽  
Total Solar Eclipse ◽  
Surface Radiation ◽  
Test Case ◽  
Data Set ◽  
Radiation Data ◽  
Exchange Processes ◽  
First Time

Abstract. On 20 March 2015, a total solar eclipse occurred over Ny-Ålesund (78.9° N, 11.9° E), Svalbard, in the high Arctic. It was the first time that the surface radiation components during the totality of a solar eclipse were measured by a Baseline Surface Radiation Network (BSRN) station. With the Ny-Ålesund long-term radiation data set as background (available at doi:10.1594/PANGAEA.150000), we present here the peculiarities of the radiation components and basic meteorology observed during the eclipse event. The supplementary data set contains the basic BSRN radiation and surface meteorological data in 1 min resolution for March 2015, and is available at doi:10.1594/PANGAEA.854326. The eclipse radiation data will be a useful auxiliary data set for further studies on micrometeorological surface–atmosphere exchange processes in the Svalbard environment, and may serve as a test case for radiative transfer studies.

scholarly journals Observation of the prominence cavity region using slitless eclipse flash spectra and space borne EUV filtergrams

2013 ◽  
Vol 8 (S300) ◽  
pp. 151-154
Author(s):  
Cyrille Bazin ◽  
Serge Koutchmy ◽  
Philippe Lamy ◽  
Ehsan Tavabi
Keyword(s):  
Electron Density ◽  
Plasma Density ◽  
Solar Eclipse ◽  
Intensity Ratio ◽  
Radial Direction ◽  
Hydrostatic Equilibrium ◽  
Total Solar Eclipse ◽  
First Time ◽  
The Continuum

AbstractWe used total solar eclipse free of parasitic light for studying the prominence to corona interface, and the corresponding cavity in the context of the coronal physics. We analysed the visible continuum between the prominences to directly look at the electron density. We demonstrate some enhanced heating in the cavity region. Some similarities with the interface regions are shown: the photosphere to the chromosphere and the prominence to the corona interface. The optically thin neutral Helium at 4713 Å and the singly ionized Helium 4686 Å Paschen α lines are considered. We summed 80 slitless visible eclipse flash spectra that we compare with simultaneously obtained EUV SWAP/Proba2 174 Å images of ESA and AIA/SDO 171Å 193 Å 304 Å and 131 Å filtergrams. Intensity profiles in a radial direction are studied. We deduce the variation of the intensity ratio I(He I 4713) / I(He II 4686). Discussion: the temperature rises at the edge of the prominences. We evaluate for the first time with spectrophotometric accuracy the continuum modulations in prominence spectra. W-L intensity deficits are observed near the prominence boundaries in both eclipse spectra and in EUV images, confirming that the prominence -cavity regions correspond to a relative depression of plasma density of the surrounding corona. Conclusion: we demonstrate some enhanced heating occurring in these regions assuming hydrostatic equilibrium.

scholarly journals Accurate 3D radiative transfer simulation of spectral solar irradiance during the total solar eclipse of August 21, 2017

2019 ◽  
Author(s):  
Paul Ockenfuß ◽  
Claudia Emde ◽  
Bernhard Mayer ◽  
Germar Bernhard
Keyword(s):  
Solar Eclipse ◽  
Solar Irradiance ◽  
Monte Carlo Model ◽  
Solar Limb ◽  
Relative Difference ◽  
Total Solar Eclipse ◽  
Ozone Profile ◽  
Increased Sensitivity ◽  
Limb Darkening ◽  
Spectral Solar Irradiance

Abstract. We calculate the variation of spectral solar irradiance in the umbral shadow of the total solar eclipse of August 21, 2017 and compare it to observations. Starting from the sun's and moon's positions, we derive a realistic profile of the lunar shadow at the top of the atmosphere, including the effect of solar limb darkening. Subsequently, the Monte-Carlo model MYSTIC is used to simulate the transfer of solar radiation through the earth's atmosphere. Among the effects taken into account are the atmospheric state (pressure, temperature), concentrations of major gas constituents and the curvature of the earth, as well as the reflectance and elevation of the surrounding area. We apply the model to the total solar eclipse on August 21, 2017 at a position located in Oregon, where irradiance observations were performed for wavelengths between 306 nm and 1020 nm. The influence of the surface reflectance, the ozone profile and mountains surrounding the observer is investigated. An increased sensitivity during totality is found for the reflectance and topography, compared to non-eclipse conditions. During the eclipse, the irradiance at the surface does not only depend on the total ozone column (TOC) but also the vertical ozone distribution, which in general complicates derivations of the TOC from spectral surface irradiance. The findings are related to an analysis of the prevailing photon path and its difference compared to non-eclipse conditions. Using the most realistic estimate for each parameter, the model is compared to the irradiance observations. During totality, the relative difference between model and observations is less than 10 % in the spectral range from 400 nm to 1020 nm. Slightly larger deviations occur in the ultraviolet range below 400 nm and at 665 nm.

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