Reduction of solar UV by clouds: A comparison between satellite‐derived cloud effects and ground‐based radiation measurements

Matthijsen, J.; Slaper, H.; Reinen, H. A. J. M.; Velders, G. J. M.

doi:10.1029/1999jd900937

Cited by 57 publications

(44 citation statements)

References 27 publications

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“…However, in some recent studies the groundbased/satellite measurements and model simulations have been used to identify changes in the surface UV and processes responsible for the UV radiation changes (e.g. McElroy, 1993, Borderwijk et al, 1995;Zerefos et al, 1995;Krzyścin, 1996;Weatherhead et al, 1997;Udelhofen et al, 1999;den Outer et al, 2000;Kaurola et al, 2000;Matthijsen et al, 2000;Eerme et al, 2002). These studies confirm that the UV changes are driven by various factors: ozone, cloudiness, aerosols, and surface albedo.…”

Section: Introductionmentioning

confidence: 84%

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

2004

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Abstract. The daily doses of the erythemally weighted UV radiation are reconstructed for three sites in Central Europe: Belsk-Poland (1966-2001, Hradec Kralove-Czech Republic (1964-2001, and Tõravere-Estonia (1967-2001 to discuss the UV climatology and the long-term changes of the UV-B radiation since the mid 1960s. Various reconstruction models are examined: a purely statistical model based on the Multivariate Adaptive Regression Splines (MARS) methodology, and a hybrid model combining radiative transfer model calculations with empirical estimates of the cloud effects on the UV radiation. Modeled long-term variations of the surface UV doses appear to be in a reasonable agreement with the observed ones. A simple quality control procedure is proposed to check the homogeneity of the biometer and pyranometer data. The models are verified using the results of UV observations carried out at Belsk since 1976. MARS provides the best estimates of the UV doses, giving a mean difference between the modeled and observed monthly means equal to 0.6±2.5%. The basic findings are: similar climatological forcing by clouds for all considered stations (∼30% reduction in the surface UV), long-term variations in UV monthly doses having the same temporal pattern for all stations with extreme low monthly values (∼5% below overall mean level) at the end of the 1970s and extreme high monthly values (∼5% above overall mean level) in the mid 1990s, regional peculiarities in the cloud long-term forcing sometimes leading to extended periods with elevated UV doses, recent stabilization of the ozone induced UV long-term changes being a response to a trendless tendency of total ozone since the mid 1990s. In the case of the slowdown of the total ozone trend over Northern Hemisphere mid-latitudes it seems that clouds will appear as the most important modulator of the UV radiation both in long-and short-time scales over next decades.

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Section: Introductionmentioning

confidence: 84%

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

2004

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“…Stratospheric ozone is especially important because it is the major atmospheric absorber of solar UV-B radiation (e.g. UNEP, 1998;Matthijsen et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2008

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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.

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“…Cloud effects for summer periods derived from the International Satellite Cloud Climatology Project (IS-CCP) data -cloud fraction and optical depth -perform a little worse than derived from the reflectivity (Matthijsen et al, 2000;Williams et al, 2004). Daily sums of UV irradiance using ISCCP data indicate a similarly good performance with respect to the standard deviations .…”

Section: Introductionmentioning

confidence: 98%

“…Many studies have demonstrated the ability (and limitations) of spaceborne measurements to assess the groundlevel UV radiation (Eck et al, 1995;Herman et al, 1999;Kalliskota et al, 2000;Matthijsen et al, 2000;Krotkov et al, 2001;Kazantzidis et al, 2006;Arola et al, 2009;Kazadzis et al, 2009). Cloud effects for summer periods derived from the International Satellite Cloud Climatology Project (IS-CCP) data -cloud fraction and optical depth -perform a little worse than derived from the reflectivity (Matthijsen et al, 2000;Williams et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…Building on the work of Matthijsen et al (2000) and Williams et al (2004), we make an assessment of the readily available reflectivity data from three consecutive operating instruments: N7-TOMS (TOMS flown on Nimbus 7), EP-TOMS, and OMI (flown on EOS Aura). We investigate how well daily sums of ground-level UV irradiance can be modelled by applying the reflectivity product, and focus on the differences between the three instruments in the determined cloud effects for UV irradiance.…”

Section: Introductionmentioning

confidence: 99%

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Applying spaceborne reflectivity measurements for calculation of the solar ultraviolet radiation at ground level

et al. 2012

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Abstract. Long-term analysis of cloud effects on ultraviolet (UV) radiation on the ground using spaceborne observations requires the use of instruments that have operated consecutively. The longest data record can be built from the reflectivity measurements produced by the instruments Total Ozone Mapping Spectrometers (TOMS) flown on Nimbus 7 from 1979 to 1992, TOMS on Earth Probe from 1996 to 2005, and the Ozone Monitoring Instrument (OMI) flown on EOS Aura since 2004. The reflectivity data produced by TOMS on Earth Probe is only included until 2002. A comparison is made with cloud effects inferred from ground-based pyranometer measurements at over 83 World Radiation Data Centre stations. Modelled UV irradiances utilizing the standard reflectivity are compared with measurements of UV irradiances at eight European low-elevation stations. The reflectivity data of the two TOMS instruments shows a consistent agreement, and the required corrections are of low percentage, i.e. 2-3 %. In contrast, the reflectivity product of OMI requires correction of 7-10 %, and a solar angle dependency therein is more pronounced. These corrections were inferred from a comparison with pyranometer data, and tested using the UV measurements. The average reduction of UV radiation due to clouds for all sites together indicates a small trend: a diminishing cloudiness, in line with ground-based UV observations. Uncorrected implementation of the reflectivity data would have indicated the opposite.An optimal area was established for reflectivity data for the calculation of daily sums of UV radiation. It measures approximately 1.25 • in latitudinal direction for square-shaped areas overhead the ground-based UV stations. Such an area can be traversed within 5 to 7 h at the average wind speeds found for the West European continent.

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Reduction of solar UV by clouds: A comparison between satellite‐derived cloud effects and ground‐based radiation measurements

Cited by 57 publications

References 27 publications

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

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

Applying spaceborne reflectivity measurements for calculation of the solar ultraviolet radiation at ground level

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