Comparison of meteorological data, related to reference evapotranspiration, from conventional and automatic stations in the Sertão and Agreste regions of Pernambuco, Brazil

The objective was to perform a comparative study of the meteorological elements data that most cause changes in reference Evapotranspiration (ETo, mm) and its own value, automatic weather stations AWS conventional CWS Sertão Agreste regions Pernambuco State. ETo calculated on daily scale using standard method proposed by Food Agriculture Organization (FAO), Penman-Monteith (FAO-56). information obtained from can be used update database stations, since there is good relationship between AWS, statistically determined Willmott's concordance index (d > 0.7). observed variations elements: air temperature, relative humidity, wind speed, global solar radiation have not caused significant calculation.