Global Aridity Index and Potential Evapotranspiration (ET0) Climate Database v3

The Global Aridity Index (Global-AI) and Global Reference Evapo-Transpiration (Global-ET0) datasets provided in Version 3 of the Global Aridity Index and Potential Evapo-Transpiration (ET0) Database (Global-AI_PET_v3) provide high-resolution (30 arc-seconds) global raster data for the 1970-2000 period, related to evapotranspiration processes and rainfall deficit for potential vegetative growth, based upon implementation of the FAO-56 Penman-Monteith Reference Evapotranspiration (ET₀) equation. Aridity Index represent the ratio between precipitation and ET₀, thus rainfall over vegetation water demand (aggregated on annual basis). Under this formulation, Aridity Index values increase for more humid conditions, and decrease with more arid conditions. The Aridity Index values reported within the <i>Global-AI</i> geodataset have been multiplied by a factor of 10,000 to derive and distribute the data as integers (with 4 decimal accuracy). This multiplier has been used to increase the precision of the variable values without using decimals. The Readme File is provided with a detailed description of the dataset files, and the following article for a description of the methodology and a technical validation.The Global-AI_PET_v3 datasets are provided for non-commercial use in standard GeoTiff format, at 30 arc seconds or ~ 1km at the equator.<br>

《全球干旱指数与潜在蒸散(ET₀)数据库v3版》（Global-AI_PET_v3）所提供的全球干旱指数（Global Aridity Index, Global-AI）与全球参考蒸散（Global Reference Evapo-Transpiration, Global-ET0）数据集，包含1970-2000年时段的高分辨率（30角秒）全球栅格数据，数据关联潜在植被生长相关的蒸散过程与降水亏缺，基于FAO-56彭曼-蒙特思参考蒸散（ET0）方程的计算实现。干旱指数为降水量与ET₀的比值，即年尺度汇总后的降雨量与植被需水量之比。按照该计算公式，干旱指数值在更湿润的环境中升高，在更干旱的环境中降低。<i>Global-AI</i>地理数据集所记录的干旱指数值已乘以10000倍，以整数形式分发（保留4位小数精度），该乘数可在不使用小数格式的前提下提升变量值的精度。数据集文件的详细说明见配套自述文件，方法学细节与技术验证内容可参考相关学术文章。Global-AI_PET_v3数据集以标准GeoTiff格式提供，仅可用于非商业用途，分辨率为30角秒，在赤道处约合1公里。<br>