Vicente-Serrano, Sergio M. Lanjeri, S. López-Moreno, Juan I. 2007-02-01 This paper compares different procedures for mapping reference evapotranspiration (ET_o) by means of regression-based techniques and geographical information systems (GIS). ET_o is calculated following the method of Hargreaves (HG) from a dense database of meteorological stations in the northernmost semi-arid region of Europe, the Ebro valley. The HG method requires the calculation of estimates of extraterrestrial radiation (<i>R</i>_a). We calculated this parameter using two approaches: (1) the common approach that assumes a planar surface and determines the parameter as a function of latitude and (2) using a digital terrain model (DTM) and GIS modelling. The maps were made on a monthly basis using both approaches. We also compared possible propagations of errors in the map calculations for maps derived from modelled layers of maximum and minimum temperatures with those modelled using previously determined local ET_o calculations. We demonstrate that calculations of <i>R</i>_a from a DTM and GIS modelling provide a more realistic spatial distribution of ET_o than those derived by only considering latitude. It is also preferable to model in advance the variables involved in the calculation of ET_o (temperature and <i>R</i>_a) and to subsequently calculate ET_o by means of layer algebra in the GIS rather than directly model the local ET_o calculations. The obtained maps are useful for the purposes of agriculture and ecological and water resources management in the study area. application/pdf https://folia.unifr.ch/global/documents/300635 https://folia.unifr.ch/documents/300635/files/lopez_cdp.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1002/joc.1460 info:eu-repo/semantics/openAccess License undefined International Journal of Climatology. - 2007, vol. 27, no. 8, p. 1103 - 1118 reference evapotranspiration geographical information systems regression-based interpolation digital terrain models Hargreaves method Ebro valley Spain info:eu-repo/classification/udc/551 Comparison of different procedures to map reference evapotranspiration using geographical information systems and regression-based techniques http://purl.org/coar/resource_type/c_6501