Dynamic procedure for daily PM56 ETo mapping conducive to site-specific irrigation recommendations in areas covered by agricultural weather networks

Abstract

Modern agriculture is underpinned by actual meteorological data registered using automated meteorological stations forming networks specifically created for advising purposes. In many cases, those data used to be accessible online by means of APIs (Application Programming Interface). One of the most common cases is the irrigation-advice weather network implemented with the aim of obtaining ETo values to be used in irrigation recommendations. However, those punctual values of ETo scattered throughout the territory do not allow to produce specific irrigation recommendations for each farm. The only way of disposing site-specific values of ETo is by compiling maps that describe its spatial variation. With this objective, a new dynamic procedure based on an existing regression-based technique of interpolation was proposed. Using the meteorological data registered at the end of each day, maximum and minimum temperature, maximum and minimum relative humidity, wind velocity, and radiation maps were interpolated and then, an ETo map was derived. The proposed procedure demonstrated a special adaptation capacity to the synoptic pattern of each day using some geographical features or others, as appropriate to explain the spatial variability of the interpolated meteorological variable. In those months where radiation plays a key role in the ETo value (growing season), ETo maps obtained were especially fine-grained in areas with significant relief. This procedure improved other contrasted methodologies they were compared with. The impact of using the nearest-weather-station ETo vs interpolated value on a daily water needs was investigated and near 10% average value of error was encountered in the case study.

Keywords

• Reference Evapotranspiration
• Regression-based Interpolation Procedures
• ETo mapping
• Agricultural weather networks