<p>This data is drought index (AI) and evapotranspiration data extracted based on Global-AI_PET_v3 for Xinjiang in China and five Central Asian countries. Geospatial data sets are provided online in GeoTIFF (.tif) format, using geographical coordinates; the datum and ellipsoid are WGS84; and the spatial unit is decimal degrees. The spatial resolution is 30 arcseconds or 0.008333 degrees (approximately 1 kilometer at the equator). The Drought Index (Global-AI) geographical dataset has been multiplied by a factor of 10,000 to export and distribute data in integer form (retaining 4 decimal places precision). AI values in GeoTIFF (.tif) files need to be multiplied by 0.0001 to obtain the correct unit value. Potential evapotranspiration was calculated using the Penman-Monteith method, and annual average precipitation (MA_Prec) data were obtained from WorldClim v 2.1 58, which is an average for the period 1970-2000. </p>
The Global Drought Index and Potential Evapotranspiration Database-Version 3 (Global-AI_PET_v3) provides high-resolution (30 arc-seconds) global hydroclimatic data based on the FAO Penman-Monteith Reference Evapotranspiration (ET0) equation, averaged monthly and annual (1970-2000). The document outlines methods for implementing the Penman-Monteith equation geospatial and provides a technical evaluation of the results. For technical verification, the results were compared with weather station data from the FAO "CLIMWAT 2.0 for CROPWAT"(ET0: r2 = 0.85;AI: r2 = 0.90) and weather station data from the UK "Climate Research Unit: Time Series v4.04"(ET0: r2 = 0.89;AI: r2 = 0.83), but there were significant differences with earlier versions of the database. The current version of Global-AI_PET_v3 replaces the previous version and is more correlated with real-world weather station data. Developed using the universally recognized standard method of reference ET0 estimation, the database, together with the accompanying source code, provides a reliable tool for various scientific applications in rapidly changing climate conditions.
The drought index classification scheme provided by the United Nations Environment Program: The climate types corresponding to an Aidity Index Value of 0.03 - 0.2 drought, 0.2 - 0.5 semi-arid, 0.5 - 0.65 dry and sub-humid, and 0.65 humid. Data file names: XJ-Xinjiang, KAZ-Kazakhstan, KGZ-Kyrgyzstan, TJK-Tajikistan, UZB-Uzbekistan, TKM-Turkmenistan, Global-Global. Explanation of key abbreviations: AI-Aidity Index Value, PET-Potential Evapotranspiration
According to the data author's description in the data paper: After technical evaluation and confirmation, the standardized FAO-56 Penman-Monteith method was used to estimate the reference evapotranspiration (ET), and the Global-AI_PET_v3 dataset generated based on geospatial algorithms provided estimates of potential evapotranspiration (PET) and drought index (AI) covering the world (resolution of 30 arcseconds). This dataset is suitable for non-critical mission applications at multiple scales at local, national, regional and even global. Although it is known that local topography, landscape heterogeneity, and interpolation processes in sparse weather station network areas increase uncertainty at the plot/field scale level, the evaluation results show that the current version has significantly improved performance compared to previous versions, and has a strong correlation with measured weather station data. According to the comprehensive technical assessment conclusion, the Global-AI_PET_v3 dataset (including source code) has been assessed as a valuable global public scientific resource. It has comparative advantages as a reference benchmark on a global scale and is a reliable tool for scientific research in the context of rapid climate change.
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10.1038/s41597-022-01493-1
