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

2008 ◽  
Vol 8 (2) ◽  
pp. 4309-4351 ◽  
Author(s):  
V. Buchard ◽  
C. Brogniez ◽  
F. Auriol ◽  
B. Bonnel ◽  
J. Lenoble ◽  
...  
Keyword(s):  
Ozone Monitoring Instrument ◽  
Dose Rates ◽  
Clear Sky ◽  
The North ◽  
Uv Irradiance ◽  
Irradiance Data ◽  
Solar Uv ◽  
Sky Conditions ◽  
Rayonnement Solaire ◽  
Good Agreement

Abstract. Ozone Monitoring Instrument (OMI), launched in July 2004, is dedicated to the monitoring of the Earth's ozone, air quality and climate. OMI provides among other things the total column of ozone (TOC), the surface ultraviolet (UV) irradiance at several wavelengths, the erythemal dose rate and the erythemal daily dose. The main objective of this work is to validate OMI data with 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 in the north of France performs solar UV measurements using a spectroradiometer and a broadband radiometer. The site of Briançon in the French Southern Alps is also equipped with a spectroradiometer operated by Interaction Rayonnement Solaire Atmosphère (IRSA). The instrument belongs to the Centre Européen Médical et Bioclimatologique de Recherche et d'Enseignement Supérieur. The comparison between the TOC retrieved with ground-based measurements and OMI TOC shows good agreement at both sites for all sky conditions. Comparisons of spectral UV on clear sky conditions are also satisfying whereas results of comparisons of the erythemal daily doses and erythemal dose rates for all sky conditions and for clear sky show that OMI overestimates significantly surface UV doses at both sites.

scholarly journals Measurements of UV irradiance within the area of one satellite pixel

2008 ◽  
Vol 8 (18) ◽  
pp. 5615-5626 ◽  
Author(s):  
P. Weihs ◽  
M. Blumthaler ◽  
H. E. Rieder ◽  
A. Kreuter ◽  
S. Simic ◽  
...  
Keyword(s):  
Ozone Monitoring Instrument ◽  
Short Term ◽  
Uv Index ◽  
Clear Sky ◽  
Uv Irradiance ◽  
Instantaneous Values ◽  
The Mean ◽  
The Difference ◽  
Sky Conditions ◽  
Better Than

Abstract. A measurement campaign was performed in the region of Vienna and its surroundings from May to July 2007. Within the scope of this campaign erythemal UV was measured at six ground stations within a radius of 30 km. First, the homogeneity of the UV levels within the area of one satellite pixel was studied. Second, the ground UV was compared to ground UV retrieved by the ozone monitoring instrument (OMI) onboard the NASA EOS Aura Spacecraft. During clear-sky conditions the mean bias between erythemal UV measured by the different stations was within the measurement uncertainty of ±5%. Short term fluctuations of UV between the stations were below 3% within a radius of 20 km. For partly cloudy conditions and overcast conditions the discrepancy of instantaneous values between the stations is up to 200% or even higher. If averages of the UV index over longer time periods are compared the difference between the stations decreases strongly. The agreement is better than 20% within a distance of 10 km between the stations for 3 h averages. The comparison with OMI UV showed for clear-sky conditions higher satellite retrieved UV values by, on the average, approximately 15%. The ratio of OMI to ground measured UV lies between 0.9 and 1.5. and strongly depends on the aerosol optical depth. For partly cloudy and overcast conditions the OMI derived surface UV estimates show larger deviation from the ground-based reference data, and even bigger systematic positive bias. Here the ratio OMI to ground data lies between 0.5 and 4.5. The average difference between OMI and ground measurements is +24 to +37% for partly cloudy conditions and more than +50% for overcast conditions.

scholarly journals Measurements of UV irradiance within the area of one satellite pixel

2008 ◽  
Vol 8 (1) ◽  
pp. 3693-3720 ◽  
Author(s):  
P. Weihs ◽  
M. Blumthaler ◽  
H. E. Rieder ◽  
A. Kreuter ◽  
S. Simic ◽  
...  
Keyword(s):  
Reference Data ◽  
Ozone Monitoring Instrument ◽  
Uv Index ◽  
Clear Sky ◽  
Uv Irradiance ◽  
Ozone Monitoring ◽  
Time Periods ◽  
The Difference ◽  
Sky Conditions ◽  
Better Than

Abstract. A measurement campaign was performed in the region of Vienna and its surroundings from May to July 2007. Within the scope of this campaign erythemal UV was measured at six ground stations within a radius of 30 km. First, the homogeneity of the UV levels within the area of one satellite pixel was studied. Second, the ground UV was compared to ground UV retrieved by the ozone monitoring instrument (OMI) onboard the NASA EOS Aura Spacecraft. During clear sky conditions the difference in erythemal UV measured by the different stations was within the measurement uncertainty of 8%. For partly cloudy conditions and total overcast conditions the discrepancy of momentary values between the stations is up to 200% or even higher. If averages of the UV index over longer time periods are compared the difference between the stations decreases strongly. The agreement is better than 20% within a distance of 10 km between the stations for 3 h averages. The comparison with OMI UV showed for clear sky conditions higher satellite retrieved UV values by on the average approximately 15%. For partly cloudy and overcast conditions the OMI derived surface UV estimates show larger deviation from the ground-based reference data, and even bigger systematic positive bias.

scholarly journals Comparison of OMI NO<sub>2</sub> observations and their seasonal and weekly cycles with ground-based measurements in Helsinki

2016 ◽  
Author(s):  
Iolanda Ialongo ◽  
Jay Herman ◽  
Nick Krotkov ◽  
Lok Lamsal ◽  
Folkert Boersma ◽  
...  
Keyword(s):  
Air Quality ◽  
Relative Difference ◽  
Urban Site ◽  
High Latitudes ◽  
Ozone Monitoring Instrument ◽  
Weekly Cycle ◽  
Clear Sky ◽  
Standard Product ◽  
Weekly Cycles ◽  
Sky Conditions

Abstract. We present the comparison of satellite-based OMI (Ozone Monitoring Instrument) NO2 products with ground-based observations in Helsinki. OMI NO2 total columns, available from standard product (SP) and DOMINO algorithm, are compared with the measurements performed by the Pandora spectrometer in Helsinki in 2012. The relative difference between Pandora #21 and OMI SP retrievals is 4 % and −6 % for clear sky and all sky conditions, respectively. DOMINO NO2 retrievals showed slightly lower total columns with median differences about −5 % and −14 % for clear sky and all sky conditions, respectively. Large differences often correspond to cloudy autumn-winter days with solar zenith angles above 65°. Nevertheless, the differences remain within the retrieval uncertainties. Furthermore, the weekly and seasonal cycles from OMI, Pandora and NO2 surface concentrations are compared. Both satellite- and ground-based data show a similar weekly cycle, with lower NO2 levels during the weekend compared to the weekdays as result of reduced emissions from traffic and industrial activities. Also the seasonal cycle shows a similar behaviour, even though the results are affected by the fact that most of the data are available during spring-summer because of cloud cover in other seasons. This is one of few works in which OMI NO2 retrievals are evaluated in a urban site at high latitudes (60° N). Despite the city of Helsinki having relatively small pollution sources, OMI retrievals have proved to be able to describe air quality features and variability similar to surface observations. This adds confidence in using satellite observations for air quality monitoring also at high latitudes.

scholarly journals Validation of Satellite Estimated Solar Ultraviolet Radiation Data with Ground Based data in Kathmandu, Nepal

2016 ◽  
Vol 11 (1) ◽  
pp. 101-107
Author(s):  
Niranjan Prasad Sharma
Keyword(s):  
Ultraviolet Radiation ◽  
Scattered Light ◽  
Visible Spectrum ◽  
Relative Difference ◽  
Ozone Monitoring Instrument ◽  
Solar Ultraviolet Radiation ◽  
Radiation Data ◽  
Uv Irradiance ◽  
Relative Differences ◽  
Solar Ultraviolet

The main objective of this study is to validate the satellite estimated solar Ultraviolet radiation data with ground based data in  Kathmandu (27.72 N, 85.32 E), located at an elevation of 1350m,  from the sea level. The ground based measurement and the satellite estimation were performed by NILU-UV irradiance meter and EOS Aura OMI satellite respectively. The NILU-UV irradiance meter is a six channel 0 0 radiometer designed to measure hemispherical irradiances on a fat surface. Meanwhile the Ozone Monitoring Instrument (OMI) on board, the NASA EOS Aura space craft is a nadir viewing spectrometer that measures solar refected and back scattered light in ultraviolet and visible spectrum. The study is based on OMI and ground based (GB), Ultraviolet Radiation (UVR) data. Considering these data the relative differences between predicted OMI and ground based Ultraviolet Index (UVI) assuming normal distribution ±1σ was found to be 24.8±13.7% in July. Further study showed that the ratio of predicted OMI, UVI to that determined from ground based measurement is 1.14. Also the relative difference in UVI in corrected condition in summer season was found to be 5.8%. The correlation between predicted UVI and ground based UVI was found to be signifcant. Journal of the Institute of Engineering, 2015, 11(1): 101-107

scholarly journals Comparison of total ozone and erythemal UV data from OMI with ground-based measurements at Rome station

2008 ◽  
Vol 8 (12) ◽  
pp. 3283-3289 ◽  
Author(s):  
I. Ialongo ◽  
G. R. Casale ◽  
A. M. Siani
Keyword(s):  
Total Ozone ◽  
Broad Band ◽  
Atmospheric Conditions ◽  
Ozone Monitoring Instrument ◽  
Dose Rates ◽  
Large Correlation ◽  
Uv Irradiance ◽  
The Difference ◽  
Band Radiometer ◽  
Local Noon

Abstract. Ground-based total ozone and surface UV irradiance measurements have been collected since 1992 using Brewer spectrophotometer at Rome station. Erythemal Dose Rates (EDRs) have been also determined by a broad-band radiometer (model YES UVB-1) operational since 2000. The methodology to retrieve the EDR and the Erythemal Daily Dose (EDD) from the radiometer observations is described. Ground-based measurements were compared with satellite-derived total ozone and UV data from the Ozone Monitoring Instrument (OMI). OMI, onboard the NASA EOS Aura spacecraft, is a nadir viewing spectrometer that provides total ozone and surface UV retrievals. The results of the validation exercise showed satisfactory agreement between OMI and Brewer total ozone data, for both OMI-TOMS and OMI-DOAS ozone algorithms (biases of −1.8% and −0.7%, respectively). Regarding UV data, OMI data overestimate ground based erythemally weighted UV irradiances retrieved from both Brewer and YES Radiometer (biases about 20%). The effect of aerosols on UV comparisons was investigated in terms of Aerosol Optical Depth (AOD), showing medium-large correlation at SZA larger than 55°. Further sources of uncertainty, such as the difference in the atmospheric conditions between local noon and OMI overpass time and the OMI spatial resolution, were also discussed.

scholarly journals Comparison of OMI NO<sub>2</sub> observations and their seasonal and weekly cycles with ground-based measurements in Helsinki

2016 ◽  
Vol 9 (10) ◽  
pp. 5203-5212 ◽  
Author(s):  
Iolanda Ialongo ◽  
Jay Herman ◽  
Nick Krotkov ◽  
Lok Lamsal ◽  
K. Folkert Boersma ◽  
...  
Keyword(s):  
Air Quality ◽  
Relative Difference ◽  
Urban Site ◽  
High Latitudes ◽  
Ozone Monitoring Instrument ◽  
Weekly Cycle ◽  
Clear Sky ◽  
Fitting Procedure ◽  
Standard Product ◽  
Sky Conditions

Abstract. We present the comparison of satellite-based OMI (Ozone Monitoring Instrument) NO2 products with ground-based observations in Helsinki. OMI NO2 total columns, available from NASA's standard product (SP) and KNMI DOMINO product, are compared with the measurements performed by the Pandora spectrometer in Helsinki in 2012. The relative difference between Pandora no. 21 and OMI SP total columns is 4 and −6 % for clear-sky and all-sky conditions, respectively. DOMINO NO2 retrievals showed slightly lower total columns with median differences about −5 and −14 % for clear-sky and all-sky conditions, respectively. Large differences often correspond to cloudy fall–winter days with solar zenith angles above 65°. Nevertheless, the differences remain within the retrieval uncertainties. The average difference values are likely the result of different factors partly canceling each other: the overestimation of the stratospheric columns causes a positive bias partly compensated by the limited spatial representativeness of the relatively coarse OMI pixel for sharp NO2 gradients. The comparison between Pandora and the new version (V3) of OMI NO2 retrievals shows a larger negative difference (about −30 %) than the current version (V2.1) because the revised spectral fitting procedure reduces the overestimation of the stratospheric column. The weekly and seasonal cycles from OMI, Pandora and NO2 surface concentrations are also compared. Both satellite- and ground-based data show a similar weekly cycle, with lower NO2 levels during the weekend compared to the weekdays as a result of reduced emissions from traffic and industrial activities. The seasonal cycle also shows a similar behavior, even though the results are affected by the fact that most of the data are available during spring–summer because of cloud cover in other seasons. This is one of few works in which OMI NO2 retrievals are evaluated in a urban site at high latitudes (60° N). Despite the city of Helsinki having relatively small pollution sources, OMI retrievals have proved to be able to describe air quality features and variability similar to surface observations. This adds confidence in using satellite observations for air quality monitoring also at high latitudes.

scholarly journals Comparison of total ozone and erythemal UV data from OMI with ground-based measurements at Rome station

2008 ◽  
Vol 8 (1) ◽  
pp. 2381-2401 ◽  
Author(s):  
I. Ialongo ◽  
G. R. Casale ◽  
A. M. Siani
Keyword(s):  
Total Ozone ◽  
Broad Band ◽  
Urban Site ◽  
Ozone Monitoring Instrument ◽  
Dose Rates ◽  
Uv Irradiance ◽  
Daily Dose ◽  
Weighted Data ◽  
Absorbing Aerosols ◽  
Band Radiometer

Abstract. Ground-based total ozone and surface UV irradiance measurements have been collected since 1992 using Brewer spectrophotometer and Erythemal Dose Rates (EDRs) have been determined by a broad-band radiometer (model YES UVB-1) operational since 2000 at Rome station. The methodology to retrieve the EDR and the Erythemal Daily Dose (EDD) from the radiometer observations is described. Ground-based measurements were compared with satellite-derived total ozone and UV data from the Ozone Monitoring Instrument (OMI). OMI, onboard the NASA EOS Aura spacecraft, is a nadir viewing spectrometer that provides total ozone and surface UV retrievals. The results of the validation exercise showed satisfactory agreement between OMI and Brewer total ozone data, for both OMI-TOMS and OMI-DOAS ozone alghorithms (biases of −1.8% and −0.7%, respectively). Regarding UV data, OMI data overestimate ground-based erythemally weighted data retrieved from both Brewer and YES Radiometer (biases about 20%), probably because of the effect of absorbing aerosols in an urban site such as Rome.

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 Monitoring Solar Radiation UV Exposure in the Comoros

2021 ◽  
Vol 18 (19) ◽  
pp. 10475
Author(s):  
Kévin Lamy ◽  
Marion Ranaivombola ◽  
Hassan Bencherif ◽  
Thierry Portafaix ◽  
Mohamed Abdoulwahab Toihir ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Cloud Cover ◽  
Relative Difference ◽  
Ozone Monitoring Instrument ◽  
Uv Index ◽  
Measurement Campaign ◽  
Monitoring Instrument ◽  
Ozone Monitoring ◽  
Sky Conditions ◽  
Very High

As part of the UV-Indien project, a station for measuring ultraviolet radiation and the cloud fraction was installed in December 2019 in Moroni, the capital of the Comoros, situated on the west coast of the island of Ngazidja. A ground measurement campaign was also carried out on 12 January 2020 during the ascent of Mount Karthala, located in the center of the island of Ngazidja. In addition, satellite estimates (Ozone Monitoring Instrument and TROPOspheric Monitoring Instrument) and model outputs (Copernicus Atmospheric Monitoring Service and Tropospheric Ultraviolet Model) were combined for this same region. On the one hand, these different measurements and estimates make it possible to quantify, evaluate, and monitor the health risk linked to exposure to ultraviolet radiation in this region and, on the other, they help to understand how cloud cover influences the variability of UV-radiation on the ground. The measurements of the Ozone Monitoring Instrument onboard the EOS-AURA satellite, being the longest timeseries of ultraviolet measurements available in this region, make it possible to quantify the meteorological conditions in Moroni and to show that more than 80% of the ultraviolet indices are classified as high, and that 60% of these are classified as extreme. The cloud cover measured in Moroni by an All Sky Camera was used to distinguish between the cases of UV index measurements taken under clear or cloudy sky conditions. The ground-based measurements thus made it possible to describe the variability of the diurnal cycle of the UV index and the influence of cloud cover on this parameter. They also permitted the satellite measurements and the results of the simulations to be validated. In clear sky conditions, a relative difference of between 6 and 11% was obtained between satellite or model estimates and ground measurements. The ultraviolet index measurement campaign on Mount Karthala showed maximum one-minute standard erythemal doses at 0.3 J·m−2 and very high daily cumulative erythemal doses, at more than 80 J·m−2. These very high levels are also observed throughout the year and all skin phototypes can exceed the daily erythemal dose threshold, at more than 20 J·m−2.

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