Quality control and gap‐filling methods applied to hourly temperature observations over central Italy
Paolina Bongioannini Cerlini, Lorenzo Silvestri, Miriam Saraceni
Abstract
Abstract Given the regional surface network of the Umbria region, a mountainous area located in central Italy, the observed hourly temperature time series from 2010 to 2017 were analysed by applying basic and extended quality control procedures following World Meteorological Organization (WMO) standards. The validation procedure consisted of automatic quality control, producing validated data with metadata subsequently recorded in the NetCDF format. After these controls, data were checked manually and an extended procedure was applied to reconstruct the temperature time series for missing data. The spatiotemporal method used to reconstruct the data was a linear interpolation for 1 hr gaps and the empirical orthogonal function (EOF) algorithm for gaps ≥ 2 hr. The introduction of a complete and homogeneous data set of hourly reanalysis ERA5 (from the European Center for Medium‐Range Weather Forecasts—ECMWF) allowed for the reconstruction of the longest gaps with statistical and physical consistency. The final product of the study is a continuous station time series of hourly temperatures that will be available to the public by the end of 2020; a daily version of the original time series is already available on the regional website.