scholarly journals Sensitivity of UV Erythemal Radiation to Total Ozone Changes under Different Sky Conditions: Results for Granada, Spain

2015 ◽  
Vol 92 (1) ◽  
pp. 215-219 ◽  
Author(s):  
Manuel Antón ◽  
Alberto Cazorla ◽  
David Mateos ◽  
Maria J. Costa ◽  
Francisco J. Olmo ◽  
...  
Keyword(s):  
Total Ozone ◽  
Sky Conditions

scholarly journals Typical distribution of the solar erythemal UV radiation over Slovakia

2008 ◽  
Vol 8 (17) ◽  
pp. 5393-5401 ◽  
Author(s):  
A. Pribullová ◽  
M. Chmelík
Keyword(s):  
Snow Cover ◽  
Total Ozone ◽  
Horizontal Resolution ◽  
Clear Sky ◽  
Global Irradiance ◽  
Daily Dose ◽  
Monthly Total ◽  
Modification Factor ◽  
Typical Distribution ◽  
Sky Conditions

Abstract. Maps of solar erythemal ultraviolet (EUV) irradiance daily doses were created for every month with a horizontal resolution of 500 m at the geographical domain 47.15 N–49.86 N×16.94 E–22.81 E covering the territory of Slovakia. The cloud modification factor for the EUV radiation (cmfUV) was modeled utilizing the relation between the cloud modification factor of global and EUV radiation. The maps of the cmfUV factor were created by utilizing measurements of global irradiance performed at nine observatories during the period 1995–2004 and modeling of the cmfUV dependence on altitude. Maps of the EUV irradiance daily dose corresponded to clear-sky conditions and EUV irradiance daily dose affected by average cloudiness were constructed for mean monthly total ozone, its upper and lower monthly limits, for two probability levels of snow cover occurrence as criteria for the snow effect incorporation in the model and for one day representing typical values for every month. The map-set can be regarded as an atlas of solar EUV radiation over Slovakia.

scholarly journals Short- and long-term variability of spectral solar UV irradiance at Thessaloniki, Greece: effects of changes in aerosols, total ozone and clouds

2016 ◽  
Vol 16 (4) ◽  
pp. 2493-2505 ◽  
Author(s):  
Ilias Fountoulakis ◽  
Alkiviadis F. Bais ◽  
Konstantinos Fragkos ◽  
Charickleia Meleti ◽  
Kleareti Tourpali ◽  
...  
Keyword(s):  
Total Ozone ◽  
Single Scattering ◽  
Data Set ◽  
Uv Irradiance ◽  
Long Term Changes ◽  
Solar Uv ◽  
Short And Long Term ◽  
Solar Uv Irradiance ◽  
Sky Conditions

Abstract. In this study, we discuss the short- and the long-term variability of spectral UV irradiance at Thessaloniki, Greece, using a long, quality-controlled data set from two Brewer spectrophotometers. Long-term changes in spectral UV irradiance at 307.5, 324 and 350 nm for the period 1994–2014 are presented for different solar zenith angles and discussed in association with changes in total ozone column (TOC), aerosol optical depth (AOD) and cloudiness observed in the same period. Positive changes in annual mean anomalies of UV irradiance, ranging from 2 to 6 % per decade, have been detected both for clear- and all-sky conditions. The changes are generally greater for larger solar zenith angles and for shorter wavelengths. For clear-skies, these changes are, in most cases, statistically significant at the 95 % confidence limit. Decreases in the aerosol load and weakening of the attenuation by clouds lead to increases in UV irradiance in the summer, of 7–9 % per decade for 64° solar zenith angle. The increasing TOC in winter counteracts the effect of decreasing AOD for this particular season, leading to small, statistically insignificant, negative long-term changes in irradiance at 307.5 nm. Annual mean UV irradiance levels are increasing from 1994 to 2006 and remain relatively stable thereafter, possibly due to the combined changes in the amount and optical properties of aerosols. However, no statistically significant corresponding turning point has been detected in the long-term changes of AOD. The absence of signatures of changes in AOD in the short-term variability of irradiance in the UV-A may have been caused by changes in the single scattering albedo of aerosols, which may counteract the effects of changes in AOD on irradiance. The anti-correlation between the year-to-year variability of the irradiance at 307.5 nm and TOC is clear and becomes clearer as the AOD decreases.

scholarly journals Short- and long-term variability of spectral solar UV irradiance at Thessaloniki, Greece: effects of changes in aerosols, total ozone and clouds

2015 ◽  
Vol 15 (24) ◽  
pp. 35753-35785
Author(s):  
I. Fountoulakis ◽  
A. F. Bais ◽  
K. Fragkos ◽  
C. Meleti ◽  
K. Tourpali ◽  
...  
Keyword(s):  
Total Ozone ◽  
Single Scattering ◽  
Data Set ◽  
Uv Irradiance ◽  
Long Term Changes ◽  
Solar Uv ◽  
Short And Long Term ◽  
Solar Uv Irradiance ◽  
Sky Conditions

Abstract. In this study, we discuss the short- and the long-term variability of spectral UV irradiance at Thessaloniki, Greece using a long, quality-controlled data set from two Brewer spectrophotometers. Long-term changes in spectral UV irradiance at 307.5, 324 and 350 nm for the period 1994–2014 are presented for different solar zenith angles and discussed in association to changes in total ozone column (TOC), aerosol optical depth (AOD) and cloudiness observed in the same period. Positive changes in annual mean anomalies of UV irradiance, ranging from 2 to 6 % per decade, have been detected both for clear- and all-sky conditions. The changes are generally greater for larger solar zenith angles and for shorter wavelengths. For clear skies, these changes are, in most cases, statistically significant at the 95 % confidence limit. Decreases in the aerosol load and weakening of the attenuation by clouds lead to increases in UV irradiance in the summer, of 7–9 % per decade for 64° solar zenith angle. The increasing TOC in winter counteracts the effect of decreasing AOD for this particular season, leading to small, statistically insignificant, negative long-term changes in irradiance at 307.5 nm. Annual mean UV irradiance levels are increasing from 1994 to 2006 and remain relatively stable thereafter, possibly due to the combined changes in the amount and optical properties of aerosols. However, no statistically significant corresponding turning point has been detected in the long-term changes of AOD. Trends in irradiance during the two sub-periods are not discussed, because the length of the two datasets is too short for deriving statistically significant estimates. The absence of signatures of changes in AOD in the short-term variability of irradiance in the UV-A may have been caused by changes in the single scattering albedo of aerosols, which may counteract the effects of changes in AOD on irradiance. The anti-correlation between the year-to-year variability of the irradiance at 307.5 nm and TOC is clear and becomes clearer as the AOD decreases.

scholarly journals Comparison of OMI ozone and UV irradiance data with ground-based measurements at two French sites

2008 ◽  
Vol 8 (16) ◽  
pp. 4517-4528 ◽  
Author(s):  
V. Buchard ◽  
C. Brogniez ◽  
F. Auriol ◽  
B. Bonnel ◽  
J. Lenoble ◽  
...  
Keyword(s):  
Total Ozone ◽  
Relative Difference ◽  
Ozone Monitoring Instrument ◽  
Dose Rates ◽  
Clear Sky ◽  
The North ◽  
Uv Irradiance ◽  
Relative Differences ◽  
Sky Conditions ◽  
Better Than

Abstract. Ozone Monitoring Instrument (OMI), launched in July 2004, is dedicated to the monitoring of the Earth's ozone, air quality and climate. OMI is the successor of the Total Ozone Mapping Spectrometer (TOMS) instruments and provides among other atmospheric and radiometric quantities the total column of ozone (TOC), the surface ultraviolet (UV) irradiance at several wavelengths, the erythemal dose rates and the erythemal daily doses. The main objective of this work is to compare OMI data with data from ground-based instruments in order to use OMI products (collection 2) for scientific studies. The Laboratoire d'Optique Atmosphérique (LOA) located in Villeneuve d'Ascq (VdA) in the north of France performs solar UV measurements using a spectroradiometer. The site of Briançon in the French Southern Alps is also equipped with a spectroradiometer operated by Interaction Rayonnement Solaire Atmosphère (IRSA). The OMI total ozone column data is obtained from the OMI-TOMS and OMI-DOAS algorithms. The comparison between the TOC retrieved with ground-based measurements and OMI-TOMS data shows good agreement at both sites for all sky conditions with a relative difference for most of points better than 5%. For OMI-DOAS data, the agreement is generally better than 7% and these data show a significant dependence on solar zenith angle. Comparisons of spectral UV on clear sky conditions are also satisfying with relative differences smaller than 10% except at solar zenith angles larger than 65°. On the contrary, results of comparisons of the erythemal dose rates and erythemal daily doses for clear sky show that OMI overestimates surface UV doses at VdA by about 15% and that on cloudy skies, the bias increases. At Briançon, such a bias is observed if data corresponding to snow-covered surface are excluded.

scholarly journals Increased UV radiation due to polar ozone chemical depletion and vortex occurrences at southern sub-polar latitudes in the period (1997–2005)

2008 ◽  
Vol 8 (2) ◽  
pp. 6501-6537
Author(s):  
A. F. Pazmino ◽  
S. Godin-Beekmann ◽  
E. A. Luccini ◽  
R. D. Piacentini ◽  
E. J. Quel ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Total Ozone ◽  
Cloud Cover ◽  
Transport Model ◽  
Austral Spring ◽  
Latitude Band ◽  
Ozone Loss ◽  
Clear Sky ◽  
Sky Conditions ◽  
The Impact

Abstract. The variability of total ozone and UV radiation from Total Ozone Mapping Spectrometer (TOMS) measurements is analyzed as a function of polar vortex occurrences over the southern subpolar regions during the 1997–2005 period. The analysis of vortex occurrences showed high interannual variability in the 40° S–60° S latitude band with a longitudinal asymmetry showing the largest frequencies over the 90° W–90° E region. The impact of vortex occurrences on UV radiation and ozone in clear sky conditions was determined from the comparison between the measurements inside the vortex and a climatology obtained from data outside the vortex over the studied period. Clear sky conditions were determined from TOMS reflectivity data. For measurements outside the vortex, clear sky conditions were selected for reflectivity values lower than 7.5%, while for measurements inside the vortex, a relaxed threshold was determined from statistically similar UV values as a function of reflectivity. UV changes and ozone differences from the climatology were analyzed in the 40° S–50° S and 50° S–60° S latitude bands during the spring period (September to November). The largest UV increases and ozone decreases, reaching 200% and 65%, respectively, were found in the 50° S–60° S latitude band in September and October. The heterogeneous ozone loss during vortex occurrences was estimated using a chemical transport model. The largest impact of vortex occurrences was found in October with mean UV increase, total ozone decrease and accumulated ozone loss in the 350 K–650 K range of respectively 47%, 32% and 63%. The region close to South America is the most affected by the Antarctic ozone depletion due to the combined effect of large number of vortex occurrences, lower cloud cover and large ozone decrease. This region would be the most vulnerable in case of cloud cover decrease linked to climate change, due to more frequent occurrence of ozone poor air masses during austral spring.

scholarly journals Increased UV radiation due to polar ozone chemical depletion and vortex occurrences at Southern Sub-polar Latitudes in the period [1997–2005]

2008 ◽  
Vol 8 (17) ◽  
pp. 5339-5352 ◽  
Author(s):  
A. F. Pazmiño ◽  
S. Godin-Beekmann ◽  
E. A. Luccini ◽  
R. D. Piacentini ◽  
E. J. Quel ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Total Ozone ◽  
Cloud Cover ◽  
Transport Model ◽  
Austral Spring ◽  
Latitude Band ◽  
Ozone Loss ◽  
Clear Sky ◽  
Sky Conditions ◽  
The Impact

Abstract. The variability of total ozone and UV radiation from Total Ozone Mapping Spectrometer (TOMS) measurements is analyzed as a function of polar vortex occurrences over the southern subpolar regions during the 1997–2005 period. The analysis of vortex occurrences showed high interannual variability in the 40° S–60° S latitude band with a longitudinal asymmetry showing the largest frequencies over the 90° W–90° E region. The impact of vortex occurrences on UV radiation and ozone in clear sky conditions was determined from the comparison between the measurements inside the vortex and a climatology obtained from data outside the vortex over the studied period. Clear sky conditions were determined from TOMS reflectivity data. For measurements outside the vortex, clear sky conditions were selected for reflectivity values lower than 7.5%, while for measurements inside the vortex, a relaxed threshold was determined from statistically similar UV values as a function of reflectivity. UV changes and ozone differences from the climatology were analyzed in the 40° S–50° S and 50° S–60° S latitude bands during the spring period (September to November). The largest UV increases and ozone decreases, reaching ~200% and ~65%, respectively, were found in the 50° S–60° S latitude band in September and October. The heterogeneous ozone loss during vortex occurrences was estimated using a chemical transport model. The largest impact of vortex occurrences was found in October with mean UV increase, total ozone decrease and accumulated ozone loss in the 350–650 K range of, respectively, 47%, 30% and 57%. The region close to South America is the most affected by the Antarctic ozone depletion due to the combined effect of large number of vortex occurrences, lower cloud cover and large ozone decrease. This region would be the most vulnerable in case of cloud cover decrease, due to more frequent occurrence of ozone poor air masses during austral spring.

scholarly journals UV Sensitivity to Changes in Ozone, Aerosols, and Clouds in Seoul, South Korea

2014 ◽  
Vol 53 (2) ◽  
pp. 310-322 ◽  
Author(s):  
Woogyung Kim ◽  
Jhoon Kim ◽  
Sang Seo Park ◽  
Hi-Ku Cho
Keyword(s):  
South Korea ◽  
Total Ozone ◽  
Ground Level ◽  
Global Solar Radiation ◽  
Regression Analyses ◽  
Uv Sensitivity ◽  
Clear Sky ◽  
Uv Irradiance ◽  
Sky Conditions

AbstractThe total ozone (O3) and aerosol optical depth (AOD) at 320 nm have been observed from the ultraviolet (UV) measurements made at Yonsei University in Seoul, South Korea, with Dobson and Brewer spectrophotometers, respectively, during 2004–10. The daily datasets are analyzed to show the sensitivities of UV radiation to changes in O3, AOD, and cloud cover (CC) together with global solar radiation (GS), including the long-term characteristics of surface UV irradiance in Seoul. The UV sensitivities show that 1% increases of O3 and AOD relative to their reference values under all- and clear-sky conditions similarly manifest as 1–1.2% and 0.2% decreases of both daily erythemal UV (EUV) and total UV (TUV) irradiance at the ground level except for TUV sensitivity to O3 (~0.3%). Those UV sensitivities to CC and GS changes are associated with a 0.12% decrease and 0.7% increase, respectively, in fractional UV changes. The trends show that the positive trends of O3 (+7.2% decade−1), AOD (+22.4% decade−1), and CC (+52.4% decade−1) induce negative trends in EUV (−8.4% decade−1) and TUV (−2.5% decade−1), in both UV (−4.7% decade−1), and in EUV (−6.3% decade−1) and TUV (−6.8% decade−1), respectively. On the basis of the multiple linear regression analyses, it is found that UV sensitivity to O3 is relatively high in the forcing factors, but the contributions of the UV forcing factors to the daily variability and the range of UV disturbances due to the variability of the forcing factors are affected more by AOD than by O3 and CC in both UV fractional changes.

scholarly journals Reconstruction of erythemal UV-doses for two stations in Austria: a comparison between alpine and urban regions

2008 ◽  
Vol 8 (20) ◽  
pp. 6309-6323 ◽  
Author(s):  
H. E. Rieder ◽  
F. Holawe ◽  
S. Simic ◽  
M. Blumthaler ◽  
J. W. Krzyścin ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Total Ozone ◽  
Input Data ◽  
Model Performance ◽  
Transfer Model ◽  
Clear Sky ◽  
Different Seasons ◽  
Input Variables ◽  
Uv Dose ◽  
Sky Conditions

Abstract. The aim of this study is the reconstruction of past UV-doses for two stations in Austria, Hoher Sonnblick and Vienna, using a physical radiation transfer model. The method uses the modeled UV-dose under clear-sky conditions, cloud modification factors and a correction factor as input variables. To identify the influence of temporal resolution of input data and modification factors, an ensemble of four different modelling approaches was calculated, each with hourly or daily resolution. This is especially important because we found no other study describing the influence of the temporal resolution of input data on model performance. Following the results of the statistical analysis of the evaluation period the model with the highest temporal resolution (HMC) was chosen for the reconstruction of UV-doses. A good agreement between modelled and measured values of erythemally effective UV-doses was found at both stations. In relation to the reference period 1976–1985 an increase in the erythemal UV-dose in Vienna of 11% is visible in the period 1986–1995 and an increase of 17% in the period 1996–2005 can be seen. At Hoher Sonnblick the corresponding increase is 2% and 9%. For the different seasons the strongest increase in erythemal UV-dose has been found for winter and spring season at both stations. Further the influences of total ozone and cloudiness on changes in erythemal UV-doses were analyzed. This analysis showed for both stations, that changes in total ozone had a larger influence on erythemal UV-doses than changes in cloudiness.

scholarly journals Ultraviolet radiation levels over Bulgarian high mountains

2021 ◽  
Vol 33 ◽  
pp. 31-39
Author(s):  
Rolf Werner ◽  
Veneta Guineva ◽  
Atanas Atanassov ◽  
Dimitar Valev ◽  
Dimitar Danov ◽  
...  
Keyword(s):  
Total Ozone ◽  
Polar Vortex ◽  
High Mountains ◽  
Satellite Measurements ◽  
High Radiation ◽  
Uv Index ◽  
Clear Sky ◽  
The Earth ◽  
Sky Conditions ◽  
Very High

The UV-index (UVI) is a measure of the erythemally effective solar radiation reaching the Earth surface and it was introduced to alert people about the need of Sun protection. The present study applies a model that estimates the UVI over the high Bulgarian mountains for clear sky conditions considering the Total Ozone Content (TOC), which was taken from satellite measurements. The results show that during the periods from May to August at altitudes above 2 000 m a.s.l. very high UVI's (greater than 8) were observed for more than 18 days per month. The UVI values were very high practically for every day of July at altitudes higher than 1 500 m. Extremely high UVI result from episodes with TOC lower than 290 DU during June and July at the highest mountain parts with elevations greater than 2 500 m. High radiation risks were observed during April, especially when the preceding polar vortex was strong and the mountains were snow covered.

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