Do the meteorological precipitation-based drought indices have the same trend and result?

Drought can be considered as a period of water deficit for an extended period of time as a result of a deficiency in its water supply. For Drought Monitor, we would quantify it. To measure and quantify drought events we use drought indices. Many subjective indices have been proposed to quantify, monitor and analyze drought for the past twentieth century due to the difficulties in objectively identifying drought characteristics according to the intensity, duration and spatiotemporal patterns. Various operational drought indices have been formulated to provide quantitative measures of when, how long, or how severe droughts are (White, 2006).These indices are normally continuous functions of some hydrometeorological variables, including rainfall, temperature, and potential evaporation.But rain-based drought indices just use precipitation data as input.

As you know we have eight precipitation-based drought indices, namely precipitation-based drought indices (SPI (Standardized Precipitation Index), PNI (Percent of Normal Index), DI (Deciles index), EDI (Effective drought index), CZI (China-Z index), MCZI (Modified CZI), RAI (Rainfall Anomaly Index), and ZSI (Z-Score Index). Every of them has special equations and they have differences on the basis of their calculations. However, Salehnia et al., (2017) showed that they have a similar trend but the severity of these drought indices are not the same.

Also, by checking all the eight indices over different regions with a various climate we can achieve the performances of the indices. Some of the indices have similar results such as SPI, DI, and PN (Quiring, 2009).

Quiring,S.(2009). Developing Objective Operational Definitions for Monitoring Drought. Journal of Applied Meteorology and Climatology 48(6), DOI: 10.1175/2009JAMC2088.1

Salehnia, N., Alizadeh, A., Sanaeinejad, H., Bannayan, M., et al. J. Journal of Arid Land (2017) 9: 797.

White D. (2006). The Utility of Seasonal Indices for Monitoring and Assessing Agricultural Drought. Report to the Australia Bureau of Rural Sciences, 778.

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