Homogenization of Monthly Rainfall Data Series in Lerma-Toluca Watershed with Climatol

The lack of availability of complete and reliable climatological data series often represents the main difficulty in carrying out hydrological studies. The causes can be diverse, such as human and instrumental errors, false and incomplete records, and the use of outdated equipment at some weather stations, which give rise to the appearance of inhomogeneities unrepresentative of the climatic reality. This study was carried out in the Lerma-Toluca Watershed, Mexico, using 145 weather stations with monthly 24-hour maximum precipitation data from 1990 to 2015. The homogenization and estimation of the missing data were conducted with the Climatol version 3.1.1 package for the statistical R application (Free software). The statistics considered were: Absolute maximum of autocorrelation of anomalies per station (ACmx), Standard normal homogeneity test (SNHT), Root mean square error (RMSE) and Percentage of original data (POD). The results obtained suggest considering an adequate percentage of original data greater than 60 % in the case of this study in order to reduce the RMSE values and keep the stations with the most complete data. The Climatol package was very versatile and practical in the homogenization and estimation of missing precipitation data.