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 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 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 Simulation of solar radiation during a total solar eclipse: a challenge for radiative transfer

2007 ◽  
Vol 7 (1) ◽  
pp. 499-535
Author(s):  
C. Emde ◽  
B. Mayer
Keyword(s):  
Solar Radiation ◽  
Radiative Transfer ◽  
Solar Eclipse ◽  
Monte Carlo Model ◽  
Three Dimensional ◽  
Diffuse Radiation ◽  
Radiative Transfer Model ◽  
Natural Phenomenon ◽  
Transfer Model ◽  
Diffuse Solar Radiation

Abstract. A solar eclipse is a rare but spectacular natural phenomenon and furthermore it is a challenge for radiative transfer modeling. Whereas a simple one-dimensional radiative transfer model with reduced solar irradiance at the top of the atmosphere can be used to calculate the brightness during partial eclipses a much more sophisticated model is required to calculate the brightness (i.e. the diffuse radiation) during the total eclipse. The reason is that radiation reaching a detector in the shadow gets there exclusively by horizontal (three-dimensional) transport of photons in a spherical shell atmosphere. In this study the first accurate simulations are presented examplified by the solar eclipse at 29 March 2006. Using a backward Monte Carlo model we calculated the diffuse radiation in the umbra and simulated the changing colors of the sky. Radiance and irradiance are decreased by 3 to 4 orders of magnitude, depending on wavelength. We found that aerosol has a comparatively small impact on the radiation in the umbra. We also estimated the contribution of the solar corona to the radiation under the umbra and found that it is negligible compared to the diffuse solar radiation in most parts of the spectrum. Spectrally resolved measurements in the umbra are not yet available. They are challenging due to the low intensity and therefore need careful planning. The new model may be used to support measurements during future solar eclipses.

scholarly journals Simulation of solar radiation during a total eclipse: a challenge for radiative transfer

2007 ◽  
Vol 7 (9) ◽  
pp. 2259-2270 ◽  
Author(s):  
C. Emde ◽  
B. Mayer
Keyword(s):  
Solar Radiation ◽  
Radiative Transfer ◽  
Solar Eclipse ◽  
Monte Carlo Model ◽  
Three Dimensional ◽  
Diffuse Radiation ◽  
Radiative Transfer Model ◽  
Natural Phenomenon ◽  
Transfer Model ◽  
Total Eclipse

Abstract. A solar eclipse is a rare but spectacular natural phenomenon and furthermore it is a challenge for radiative transfer modelling. Whereas a simple one-dimensional radiative transfer model with reduced solar irradiance at the top of the atmosphere can be used to calculate the brightness during partial eclipses a much more sophisticated model is required to calculate the brightness (i.e. the diffuse radiation) during the total eclipse. The reason is that radiation reaching a detector in the shadow gets there exclusively by horizontal transport of photons in a spherical shell atmosphere, which requires a three-dimensional radiative transfer model. In this study the first fully three-dimensional simulations for a solar eclipse are presented exemplified by the solar eclipse at 29 March 2006. Using a backward Monte Carlo model we calculated the diffuse radiation in the umbra and simulated the changing colours of the sky. Radiance and irradiance are decreased by 3 to 4 orders of magnitude, depending on wavelength. We found that aerosol has a comparatively small impact on the radiation in the umbra. We also estimated the contribution of the solar corona to the radiation under the umbra and found that it is negligible compared to the diffuse solar radiation in the wavelength region from 310 to 500 nm.

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 Study of the effect of different type of aerosols on UV-B radiation from measurements during EARLINET

2003 ◽  
Vol 3 (5) ◽  
pp. 4671-4700
Author(s):  
D. S. Balis ◽  
V. Amiridis ◽  
C. Zerefos ◽  
A. Kazantzidis ◽  
S. Kazadzis ◽  
...  
Keyword(s):  
Total Ozone ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Combined Use ◽  
Lidar Measurements ◽  
The Vertical Distribution ◽  
Aerosol Type

Abstract. Routine lidar measurements of the vertical distribution of the aerosol extinction coefficient and the extinction-to-backscatter ratio have been performed at Thessaloniki, Greece using a Raman lidar system in the frame of the EARLINET project since 2000. Spectral and broadband UV-B irradiance measurements, as well as total ozone observations, were available whenever lidar measurements were obtained. From the available measurements several cases could be identified that allowed the study of the effect of different types of aerosol on the levels of the UV-B solar irradiance at the Earth's surface. The TUV radiative transfer model has been used to simulate the irradiance measurements, using total ozone and the lidar aerosol data as input. From the comparison of the model results with the measured spectra the effective single scattering albedo was determined using an iterative procedure, which has been verified against results from the 1998 Lindenberg Aerosol Characterization Experiment. It is shown that the same aerosol optical depth and same total ozone values can show differences up to 10% in the UV-B irradiance at the Earth's surface, which can be attributed to differences in the aerosol type. It is shown that the combined use of the estimated single scattering albedo and the measured extinction-to-backscatter ratio leads to a better characterization of the aerosol type probed.

scholarly journals Description of the Baseline Surface Radiation Network (BSRN) station at the Izaña Observatory (2009–2017): measurements and quality control/assurance procedures

2019 ◽  
Vol 8 (1) ◽  
pp. 77-96 ◽  
Author(s):  
Rosa Delia García ◽  
Emilio Cuevas ◽  
Ramón Ramos ◽  
Victoria Eugenia Cachorro ◽  
Alberto Redondas ◽  
...  
Keyword(s):  
Quality Control ◽  
Research Programme ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
High Mountain ◽  
Total Column Ozone ◽  
The World ◽  
Instantaneous Values

Abstract. The Baseline Surface Radiation Network (BSRN) was implemented by the World Climate Research Programme (WCRP) starting observations with nine stations in 1992, under the auspices of the World Meteorological Organization (WMO). Currently, 59 BSRN stations submit their data to the WCRP. One of these stations is the Izaña station (station IZA, no. 61) that enrolled in this network in 2009. This is a high-mountain station located in Tenerife (Canary Islands, Spain, at 28.3∘ N, 16.5∘ W; 2373 m a.s.l.) and is a representative site of the subtropical North Atlantic free troposphere. It contributes with basic-BSRN radiation measurements, such as global shortwave radiation (SWD), direct radiation (DIR), diffuse radiation (DIF) and longwave downward radiation (LWD), and extended-BSRN measurements, including ultraviolet ranges (UV-A and UV-B), shortwave upward radiation (SWU) and longwave upward radiation (LWU), and other ancillary measurements, such as vertical profiles of temperature, humidity and wind obtained from radiosonde profiles (WMO station no. 60018) and total column ozone from the Brewer spectrophotometer. The IZA measurements present high-quality standards since more than 98 % of the data are within the limits recommended by the BSRN. There is an excellent agreement in the comparison between SWD, DIR and DIF (instantaneous and daily) measurements with simulations obtained with the LibRadtran radiative transfer model. The root mean square error (RMSE) for SWD is 2.28 % for instantaneous values and 1.58 % for daily values, while the RMSE for DIR is 2.00 % for instantaneous values and 2.07 % for daily values. IZA is a unique station that provides very accurate solar radiation data in very contrasting scenarios: most of the time under pristine sky conditions and periodically under the effects of the Saharan air layer characterized by a high content of mineral dust. A detailed description of the BSRN program at IZA, including quality control and quality assurance activities, is given in this work.

scholarly journals Aerosol trends as a potential driver of regional climate in the central United States: evidence from observations

2017 ◽  
Vol 17 (22) ◽  
pp. 13559-13572 ◽  
Author(s):  
Daniel H. Cusworth ◽  
Loretta J. Mickley ◽  
Eric M. Leibensperger ◽  
Michael J. Iacono
Keyword(s):  
United States ◽  
Radiative Transfer ◽  
Southeastern United States ◽  
Radiant Energy ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Clear Sky

Abstract. In situ surface observations show that downward surface solar radiation (SWdn) over the central and southeastern United States (US) has increased by 0.58–1.0 Wm−2 a−1 over the 2000–2014 time frame, simultaneously with reductions in US aerosol optical depth (AOD) of 3.3–5.0  ×  10−3 a−1. Establishing a link between these two trends, however, is challenging due to complex interactions between aerosols, clouds, and radiation. Here we investigate the clear-sky aerosol–radiation effects of decreasing US aerosols on SWdn and other surface variables by applying a one-dimensional radiative transfer to 2000–2014 measurements of AOD at two Surface Radiation Budget Network (SURFRAD) sites in the central and southeastern United States. Observations characterized as clear-sky may in fact include the effects of thin cirrus clouds, and we consider these effects by imposing satellite data from the Clouds and Earth's Radiant Energy System (CERES) into the radiative transfer model. The model predicts that 2000–2014 trends in aerosols may have driven clear-sky SWdn trends of +1.35 Wm−2 a−1 at Goodwin Creek, MS, and +0.93 Wm−2 a−1 at Bondville, IL. While these results are consistent in sign with observed trends, a cross-validated multivariate regression analysis shows that AOD reproduces 20–26 % of the seasonal (June–September, JJAS) variability in clear-sky direct and diffuse SWdn at Bondville, IL, but none of the JJAS variability at Goodwin Creek, MS. Using in situ soil and surface flux measurements from the Ameriflux network and Illinois Climate Network (ICN) together with assimilated meteorology from the North American Land Data Assimilation System (NLDAS), we find that sunnier summers tend to coincide with increased surface air temperature and soil moisture deficits in the central US. The 1990–2015 trends in the NLDAS SWdn over the central US are also of a similar magnitude to our modeled 2000–2014 clear-sky trends. Taken together, these results suggest that climate and regional hydrology in the central US are sensitive to the recent reductions in aerosol concentrations. Our work has implications for severely polluted regions outside the US, where improvements in air quality due to reductions in the aerosol burden could inadvertently pose an enhanced climate risk.

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