Improved quality control protocols on solar radiation measurements

This article presents a proposed set of comprehensive quality control tests on solar radiation measurements (global horizontal, direct normal and diffuse horizontal components) that allow for the automated identification of incorrect measurements. The proposed set is a combination of existing tests from different sources, chosen, and some adapted, to identify most problems in the collected data at one-minute temporal resolution, and are applied here to values measured with high-precision stations at two different sites, to derive quality flags for each entry in order to assess whether these tests are able to identify problems in the measured data, i.e., to point out data of dubious quality. The results show that this set of tests is able to spot issues which may be otherwise unidentified by the widely used BSRN set of tests, impacting calculated yearly-averaged irradiances by sometimes small, but not negligible, amounts, of as much as 4% even in a well-maintained station.