A meta-analytic review on the spatial and climatic distribution of meteorological drought indices

Abnormalities in climate in recent years have been attributed to climate change. In particular, an increase in the frequency of droughts has started to influence the way we live. There is an urgent need to study and monitor droughts to prevent severe damage. Drought monitoring research is conducted using the meteorological drought index, a compilation of weather data. Although weather data are highly dependent on climatic zones, existing studies have not considered the drought index by climatic zones. This study aims to identify the spatial and climatic distribution of meteorological drought index studies and provide a well-matched combination of the drought index and climatic classification through a meta-analytic review. Data were used in the form of research papers covering the Palmer Drought Severity Index (PDSI), Standardized Precipitation Index (SPI), and Standardized Precipitation Evapotranspiration Index (SPEI) published from 2011 to 2021. The trends showed that SPEI has become a leading index for the study of drought monitoring among the three drought indices since 2015. Additionally, Asia was the focus of much of this drought research due to climate events in China. Each continent and climate classification was assigned to a different dominant drought index. For example, PDSI was commonly used in North America and continental climates, SPI in Africa, Europe, South America, and tropical and dry climates, and SPEI in Asia and temperate climates. This evaluates countries, in which drought monitoring studies are rare, using a meteorological index based on the same climatic zones. Monitoring and predicting drought patterns would improve the basic needs of humankind.