Frequência de registros de variáveis meteorológicas para o cálculo da evapotranspiração de referência

Abstract

Agriculture faces the challenge of ensuring global food security amidst continued population growth and the occurrence of abiotic stresses, such as water deficit. The installation of irrigation systems and proper management, via estimation of reference evapotranspiration with a minimum and accurate set of meteorological data, is essential in agricultural systems. Thus, this study aimed to characterize the database of meteorological variables under different recording frequencies and climate classifications and to determine the minimum recording frequency of the measured meteorological variables, aiming at calculating reference evapotranspiration. Meteorological data (air temperature and relative humidity, incident global solar radiation and wind speed) were obtained at 15-minute intervals from three meteorological stations located in locations with different Köppen climate classifications (Aw, Cfa and Cwa), from the date of foundation until 2022. From the original database, nine other recording frequencies for each meteorological variable were simulated and the reference evapotranspiration was estimated using the Penman-Monteith method. Descriptive analyses and cluster analysis were performed using the Hierarchical Agglomerative Method of the furthest neighbor, defining the largest Euclidean distance between two elements to determine the frequency with the largest recording interval, which was grouped in the cluster where the frequency of the original data was present. To form the groups, the 70% similarity limit was used and the results were represented by dendrograms. Statistical analyses were performed using R software and Microsoft Excel, with a significance level of 0.05 error probability. The Cwa climate presented the highest average air temperature, while the Cfa climate presented the lowest averages, with greater variability. For relative humidity, the Cfa climate recorded the highest averages with the lowest variability. The incident global solar radiation was higher in the Aw climate, and the wind speed was higher in the Cfa and Aw climates. The average reference evapotranspiration was also higher in the Aw climate. The minimum frequency of recording meteorological variables obtained through meteorological stations in order to calculate the reference evapotranspiration was 2-hour intervals, which is recommended for the different climate classifications.