Global Aridity Index 1970-2000 (CGIAR, 2019)

Version 2. Aridity is usually expressed as a generalized function of precipitation, temperature and reference evapo-transpiration (ET0). An Aridity Index (UNEP, 1997) can be used to quantify precipitation availability over atmospheric water demand. This dataset shows moisture availability for potential growth of reference vegetation excluding the impact of soil mediating water runoff events. Aridity Index values increase for more humid conditions, and decrease with more arid conditions. Global-Aridity_ET0 is available as one grid layer representing the annual average over the 1970-2000 period. The Aridity Index values reported within the Global Aridity Index_ET0 geodataset have been multiplied by a factor of 10,000 to derive and distribute the data as integers (with 4 decimal accuracy). Generalized climate classification scheme for Aridity Index values (UNEP 1997).

Aridity Index Value | Climate Class < 0.03 | Hyper Arid 0.03 – 0.2 | Arid 0.2 – 0.5 | Semi-Arid 0.5 – 0.65 | Dry sub-humid

0.65 | Humid The Global Aridity Index (Global-Aridity_ET0) dataset provide high-resolution (30 arc-seconds) global raster climate data for the 1970-2000 period, related to evapo-transpiration processes and rainfall deficit for potential vegetative growth, based upon implementation of a Penman Montieth Reference Evapotranspiration (ET0) equation. The geo-spatial datasets has been produced by Antonio Trabucco and Robert Zomer, with the support of the CGIAR-CSI (funding from IFPRI Project No. 203008.000.002 515-01-01). These datasets have been downloaded and are available from the CGIAR-CSI GeoPortal [https://cgiarcsi.community]. The Consortium for Spatial Information (CGIAR-CSI) is an initiative of the Consultative Group for International Agriculture Research (CGIAR), linking the international science, research and development communities, with CGIAR scientists, national and international partners, and others working to apply and advance geospatial science for sustainable development, conservation, and poverty alleviation in developing countries. The Global-Aridity_ET0 and Global-ET0 datasets are provided for non-commercial use in standard GeoTiff format, at 30 arc seconds or ~ 1km at the equator, to support studies contributing to sustainable development, biodiversity and environmental conservation, poverty alleviation, and adaption to climate change globally, and in particular in developing countries. Comments, feedback, suggestions or bug reports regarding downloading of the Global-ET0 and Global-Aridity datasets should be sent to: csi@cgiar.org. Technical questions regarding the Global-ET0 and Global-Aridity_ET0 datasets can be directed to Antonio Trabucco: antoniotrabucco@cmcc.it . Trabucco, A., and Zomer, R.J. 2018. Global Aridity Index and Potential Evapo-Transpiration (ET0) Climate Database v2. CGIAR Consortium for Spatial Information (CGIAR-CSI). Published online, available from the CGIAR-CSI GeoPortal at https://cgiarcsi.community [https://cgiarcsi.community]