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ABSTRACT - Analysing the homogeneity of air temperature, relative air humidity, precipitation and wind data series using 'Climatol' and meteorological metadata. Errors are inherent in all measurement activity, and meteorology is no exception. Homogenization of climatological series to eliminate disturbances often contained in them, due to changes in the conditions of observations, is a mandatory process to increase the reliability of studies of climate variability derived from their analysis. The "Climatol" R package is devoted to the problem of homogenizing climatological data series in order to remove the perturbations produced e.g. by changes in the conditions of observation or in the nearby environment, to allow the series to reflect the climatic variations. As it is known, changes in the location of meteorological observatories, changes in instrumentation (from classic equipment to automated sensors) or in shelters intended to protect sensors from solar radiation, or even changes in the environment (land uses, new constructions, etc.) are alterations that can not be attributed to changes in the climate. Such information regarding this changes are known as "metadata". In this paper the "Climatol" method was used for air temperature, relative air humidity, precipitation and wind daily data homogenization for the period since 1961 till 2015 at Cluj-Napoca, Oradea, Satu Mare and Vlădeasa 1800 meteorological stations. With the help of metadata, the results were validated and changes in statistical parameters of meteorological data string were identified, for the analysed meteorological parameters, due to the relocation of the meteorological platforms, changes of the meteorological equipment and changes of the measuring methodology.
Keywords: homogenization, Climatol method, meteorological metadata, station history
1. INTRODUCTION
The homogenization process of climatological data series is a practice that should not be overlooked and necessary to ensure the quality of the meteorological data used in various studies and analyzes. The "Climatol" Package developed especially for R statistical software helps in the process for climatological data series homogenization by reducing disturbances caused by various changes in measurement conditions (eg meteorological platform relocation, installing of Automatic Weather Station (A.W.S.), changes of measuring equipment). Implemented functionalities include the comparison of each original series with a reference one (computed as a weighted average of normalized values of the other series), and the visual inspection of graphs of the data and their...