Abstract
Abstract. The data flow involved in a long-term continuous solar spectral UV irradiance monitoring program is investigated and structured to provide an overall view on the multiphase process from data acquisition to the final products. The program employing Brewer spectrophotometers as measuring instruments is maintained by the Finnish Meteorological Institute (FMI) ever since the 1990s at two sites in Finland: Sodankylä (67° N) and Jokioinen (61° N). It is built upon rigorous operation routines, processing procedures, and tools for quality control (QC) and quality analysis (QA) under continuous development and evaluation. Three distinct levels of data emerge, each after certain phase in the data flow: Level 0 denoting raw data, Level 1 meaning calibrated data processed in near-real time, and Level 2 comprising of postprocessed data corrected for all distinguishable errors and known inaccuracies. The final products disseminated to the users are demonstrated to result from a process with a multitude of separate steps, each required in the production of high-quality data on solar UV radiation at the Earth's surface.
Highlights
The Brewer spectrophotometer (Brewer) was initially designed to measure total column ozone with the differential absorption method (Bais et al, 1996; Brewer, 1973) using the direct sun port
In another companion paper (Heikkilä et al, 2016) we describe how the quality indicators provided by the European UV database (EUVDB) may be used for quality assurance of Level 2 data
To demonstrate the different phases in the data flow and the way the data are transformed as they go through the whole chain from the raw counts to final products, we use one selected case spectrum measured by Brewer no. 107 in Jokioinen on 20 May 2007
Summary
The Brewer spectrophotometer (Brewer) was initially designed to measure total column ozone with the differential absorption method (Bais et al, 1996; Brewer, 1973) using the direct sun port. The first Brewer spectrophotometers in Finland were set up in 1990 and 1995, in Sodankylä and Jokioinen, respectively, to respond to the need to monitor total ozone and UV radiation after the discovery of the Arctic ozone loss These time series of solar spectral UV irradiance of over 20 years are unique and among the longest measured in the Arctic. In a companion paper (Mäkelä et al, 2016) we describe in detail how the final time series of the responsivity of a Brewer spectrophotometer is derived In another companion paper (Heikkilä et al, 2016) we describe how the quality indicators provided by the European UV database (EUVDB) may be used for quality assurance of Level 2 data
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