Spatial characterization of the air temperature (Tar) and the reference evapotranspiration (ETo) with the McGuinness - Bordne, Hargreaves - Samani and Thornthwaite methods in the bolivian territory

Abstract

The objective of this study was to analyze the spatial behavior of monthly air temperature (Tar) (mean (Tmed), maximum (Tmax), and minimum (Tmin)) and reference evapotranspiration (ETo) using the McGuinness-Bordne, Hargreaves-Samani, and Thornthwaite methods. A database of 235 weather stations in Bolivia and 41 stations from neighboring countries was used. Geostatistical models were applied to generate Tar isothermal maps and ETo isoline maps. The results revealed a significant influence of altitude on Tar and ETo, with higher values observed in the Plains (low areas) and lower values in the Andean zone (high areas). The McGuinness-Bordne method provided the best distribution of ETo estimates, ranging between 6.8 and 1.6 mm day^-1 throughout Bolivia. The Hargreaves-Samani method showed limitations at different altitudes, estimating narrow values of 5.2 to 3 mm day^-1. The Thornthwaite method estimated lower values of 4.8 to 1.4 mm day^-1 and proved to be more accurate for Tar above 20 °C.