New daily homogenized database for Catalonia using ACMANTv5 (1950-2021)

A new data set of quality-controlled and homogenized daily maximum (TX) and minimum (TN) temperature and precipitation (PPT) for Catalonia is presented. For temperature, the dataset includes 26 TX and TN long-term series, covering most of the period 1950–2021, while a subset of 7 additional series is also included as a support, but covering a shorter period. For precipitation, a set of 71 daily PPT series is considered, covering the period 1950-2021. Although the number of series is important enough for a geographical area such as Catalonia (32,000 square kilometres), the Pyrenean region is underrepresented. For this reason, the database incorporates two Andorran series.

First of all, a description of the quality control protocol implemented for the detection of erroneous daily observations is shown. It is based on a combination of both, semiautomatic filters and visual data inspection, and special attention is paid for correction of data displacement error.

Secondly, a short description of the methodology for creating long blended series is shown, based on completeness, continuity and location (both altitude and distance) criteria. Then, time series homogeneity is addressed by means of ACMANTv5, one of the best relative homogenization methods, and firstly used on a climate dataset in this work.

Finally, a description of the results of annual and seasonal trends for the whole dataset is provided. Trends are compared with the previous dataset used in Catalonia, that was homogenized using a combination of two approaches: HOMER (monthly time series) and Vincent (transfer of monthly adjustments to daily values). In addition, some climate extreme indicators based on daily time series are also calculated for Catalonia, as part of the Yearly Bulletin of Climate Indicators released by the Meteorological Service of Catalonia (SMC). The homogenized series will be regularly updated and are already available throughout the webpage of the SMC.