Version 3 of the Global Aridity Index and Potential Evapotranspiration Database

TLDR

The Global‑AI_PET_v3 delivers 30‑arcsecond resolution global hydro‑climatic data (1970‑2000) derived from the FAO Penman‑Monteith reference evapotranspiration equation. The database was constructed by geospatially applying the Penman‑Monteith equation and includes a technical evaluation of the results. Validation against FAO CLIMWAT 2.0 and UK CM4.04 weather station data shows strong correlations (r²≈0.85–0.90) and higher agreement than earlier database versions, confirming the improved accuracy of Global‑AI_PET_v3 as a robust tool for scientific applications.

Abstract

Abstract The “Global Aridity Index and Potential Evapotranspiration Database - Version 3” (Global-AI_PET_v3) provides high-resolution (30 arc-seconds) global hydro-climatic data averaged (1970–2000) monthly and yearly, based upon the FAO Penman-Monteith Reference Evapotranspiration (ET 0 ) equation. An overview of the methods used to implement the Penman-Monteith equation geospatially and a technical evaluation of the results is provided. Results were compared for technical validation with weather station data from the FAO “CLIMWAT 2.0 for CROPWAT” ( ET 0 : r 2 = 0 .85; AI: r 2 = 0.90 ) and the U.K. “Climate Research Unit: Time Series v 4.04” ( ET 0 : r 2 = 0 .89; AI: r 2 = 0 .83 ), while showing significant differences to an earlier version of the database. The current version of the Global-AI_PET_v3 supersedes previous versions, showing a higher correlation to real world weather station data. Developed using the generally agreed upon standard methodology for estimation of reference ET 0 , this database and notably, the accompanying source code, provide a robust tool for a variety of scientific applications in an era of rapidly changing climatic conditions.