Partner: Universi\u00e4t Freiberg und sglux GmbH
\nperiod: 2017 – 2018<\/p>\n
Abstract<\/em> \u00b9Egli et al. Quality assessment of solar UV irradiance measured with array spectroradiometers, Atmos. Meas. Tech., 9, 1553\u20131567, 2016<\/p>\n","protected":false},"excerpt":{"rendered":" Partner: Universi\u00e4t Freiberg und sglux GmbH Abstract<\/em> \n\u00b9Egli et al. Quality assessment of solar UV irradiance measured with array spectroradiometers, Atmos. Meas. Tech., 9, 1553\u20131567, 2016<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[523,188],"tags":[],"class_list":{"0":"post-10842","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-abgeschlossene-arbeiten","7":"category-recherche-fr","8":"entry"},"acf":[],"yoast_head":"\n
\nThe UV-Index according to ISO 17166 is a measure of the risk of sunburn (erythema solare) at a given solar irradiance. Governmental meteorological institutes measure the UV-Index with spectroradiometers. Due to high investment and maintenance costs of these spectroradiometers, the use of small, rugged and low maintenance UV-Index-Radiometers should be a matter of evaluation, in particular when meteorological networks are planned to be extended.
\nTo evaluate the performance these UV-Index-Radiometers, basically the measurement uncertainty needs to be investigated and compared with the measurement uncertainty obtained by spectroradiometers. Egli et al.\u00b9 report the typical UV-Index-spectrometer measurement uncertainty with \u00b1 5 %. To investigate the measurement uncertainty of UV- Index-Radiometers, a bundle of 2073 different sun spectra with a range from UVI 0.5 until UVI 13.5 was used. They were traceably obtained at different places at the earth where the solar situation was influenced by latitude, altitude, season and daytime. Using the formula reported by ISO 17166 the UV-Index was calculated for each of the different sun spectra. Subsequently spectral responsivity curve of seven different UV-Index-Radiometers (manufactured by sglux GmbH) was integrated with the 2073 different sun spectra (according to ISO 17166) and in total 14,511 different UV-Indices were calculated. The differences of spectral responsivity of the seven candidates result from inevitable production tolerances of the UV-Index-Radiometers. These 14,511 different UV-Indices obtained by the UV-Index- Radiometer were compared with the related UV-Indices calculated by the formula stated in ISO 17166.
\nAs a result we could demonstrate that the spectral responsivity variance of the seven different UV-Index-Radiometers did not result a measurable influence on the measurement uncertainty. However, we saw an influence caused by the different sun spectra. In particular at extremely low UV-Indices of below 0.5 the measurement uncertainty increased. We saw that this measurement uncertainty follows a definable rule which allowed us to develop a gain matrix programmable into the radiometer\u2019s firmware. After applying of this matrix the measurement uncertainty could be reduced down to \u00b1 5 %, also for extremely low UV-Index values.
\nAccordingly, the study shows that the measurement uncertainty of the sglux UV-Index- radiometers is at the same level as reported from UV-Index-spectroradiometers. This result encourages to expand the investigation into the area of the UV-Index-Radiometers field of view (FOV). The ISO 17166 standard claims a FOV close to the cosine curve. If this FOV investigation would also result good results compared with UV-Index-Spectrometers one may regard the UV-Index-Radiometers as a reliable completion or even substitution of the spectroradiometers. This would create new opportunities to measure the UV-Index in regions where skilled personnel needed to maintain the spectroradiometers is not available.<\/p>\n
\nperiod: 2017 – 2018<\/p>\n
\nThe UV-Index according to ISO 17166 is a measure of the risk of sunburn (erythema solare) at a given solar irradiance. Governmental meteorological institutes measure the UV-Index with spectroradiometers. Due to high investment and maintenance costs of these spectroradiometers, the use of small, rugged and low maintenance UV-Index-Radiometers should be a matter of evaluation, in particular when meteorological networks are planned to be extended.
\nTo evaluate the performance these UV-Index-Radiometers, basically the measurement uncertainty needs to be investigated and compared with the measurement uncertainty obtained by spectroradiometers. Egli et al.\u00b9 report the typical UV-Index-spectrometer measurement uncertainty with \u00b1 5 %. To investigate the measurement uncertainty of UV- Index-Radiometers, a bundle of 2073 different sun spectra with a range from UVI 0.5 until UVI 13.5 was used. They were traceably obtained at different places at the earth where the solar situation was influenced by latitude, altitude, season and daytime. Using the formula reported by ISO 17166 the UV-Index was calculated for each of the different sun spectra. Subsequently spectral responsivity curve of seven different UV-Index-Radiometers (manufactured by sglux GmbH) was integrated with the 2073 different sun spectra (according to ISO 17166) and in total 14,511 different UV-Indices were calculated. The differences of spectral responsivity of the seven candidates result from inevitable production tolerances of the UV-Index-Radiometers. These 14,511 different UV-Indices obtained by the UV-Index- Radiometer were compared with the related UV-Indices calculated by the formula stated in ISO 17166.
\nAs a result we could demonstrate that the spectral responsivity variance of the seven different UV-Index-Radiometers did not result a measurable influence on the measurement uncertainty. However, we saw an influence caused by the different sun spectra. In particular at extremely low UV-Indices of below 0.5 the measurement uncertainty increased. We saw that this measurement uncertainty follows a definable rule which allowed us to develop a gain matrix programmable into the radiometer\u2019s firmware. After applying of this matrix the measurement uncertainty could be reduced down to \u00b1 5 %, also for extremely low UV-Index values.
\nAccordingly, the study shows that the measurement uncertainty of the sglux UV-Index- radiometers is at the same level as reported from UV-Index-spectroradiometers. This result encourages to expand the investigation into the area of the UV-Index-Radiometers field of view (FOV). The ISO 17166 standard claims a FOV close to the cosine curve. If this FOV investigation would also result good results compared with UV-Index-Spectrometers one may regard the UV-Index-Radiometers as a reliable completion or even substitution of the spectroradiometers. This would create new opportunities to measure the UV-Index in regions where skilled personnel needed to maintain the spectroradiometers is not available.<\/p>\n