In search of traceability : two decades of calibrated Brewer UV measurements in Sodankyla and Jokioinen

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Heikkilä , A , Makelä , J S , Lakkala , K , Meinander , O , Kaurola , J , Koskela , T , Karhu , J M , Karppinen , T , Kyro , E & De Leeuw , G 2016 , ' In search of traceability : two decades of calibrated Brewer UV measurements in Sodankyla and Jokioinen ' Geoscientific Instrumentation, Methods and Data Systems , vol. 5 , no. 2 , pp. 531-540 . DOI: 10.5194/gi-5-531-2016

Title: In search of traceability : two decades of calibrated Brewer UV measurements in Sodankyla and Jokioinen
Author: Heikkilä, Anu; Makelä, Jakke Sakari; Lakkala, Kaisa; Meinander, Outi; Kaurola, Jussi; Koskela, Tapani; Karhu, Juha Matti; Karppinen, Tomi; Kyro, Esko; De Leeuw, Gerrit
Contributor: University of Helsinki, Department
Date: 2016-11-22
Language: eng
Number of pages: 10
Belongs to series: Geoscientific Instrumentation, Methods and Data Systems
ISSN: 2193-0856
URI: http://hdl.handle.net/10138/172452
Abstract: The two Brewer spectrophotometers of the Finnish Meteorological Institute at Jokioinen and Sodankyla have been operated according to the highest levels of the WMO/GAW (World Meteorological Organization/Global Atmosphere Watch) recommendations with rigorous quality control and quality assurance. The calibration of the instruments is based on annual recalibrations of primary standard lamps in the VTT MIKES Metrology National Standards Laboratory in Finland and an exhaustive measurement program with measurements of standard and working lamps in the on-site optical laboratories. Over the years, the maintenance of the calibration has produced data sets of approximately 2000 lamp scans for both instruments. An extensive re-examination of the lamp measurements and the response of the spectrophotometers was carried out. The primary standard lamps were found to age on an average rate of 0.3% per burn. The responsivity at wavelength 311 nm was found to exhibit both long-term and short-term changes. The overall long-term change was declining. In addition, abrupt changes of as large as 25% were detected. The short-term changes were found to fluctuate on time frames shorter than the interval between the measurements of the primary standard lamps. This underlines the importance of the use of more frequently measured working standard lamps.
Subject: SPECTRAL IRRADIANCE MEASUREMENTS
GROUND-BASED MEASUREMENTS
QUALITY-ASSURANCE
TOTAL OZONE
SPECTRORADIOMETER
EUROPE
OMI
114 Physical sciences
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