Standardised Precipitation Evapotranspiration Index
The Standardized Precipitation Evapotranspiration Index (SPEI) is a multiscalar drought index based on climatic data. It was developed by Vicente-Serrano et al. (2010) at the Institute Pirenaico de Ecologia in Zaragoza, Spain.[1] It can be used for determining the onset, duration and magnitude of drought conditions with respect to normal conditions in a variety of natural and managed systems such as crops, ecosystems, rivers, water resources, etc.[2][3][4]
The SPEI accounts not only for precipitation deficit but also for the role of the increased atmospheric evaporative demand on drought severity.[5] Evaporative demand is particularly dominant during periods of precipitation deficit. The SPEI calculation requires long-term and high-quality precipitation and atmospheric evaporative demand datasets. These can be obtained from ground stations or gridded data based on reanalysis as well as satellite and multi-source datasets.[5]
Datasets
Globally, the SPEIbase and Global Precipitation Climatology Centre (GPCC) drought index datasets are available at a relatively coarse spatial resolution. The SPEIbase is available at 0.5° resolution calculated from the Climatic Research Unit precipitation and potential evapotranspiration datasets. The GPCC drought index provides SPEI datasets at a 1.0° spatial resolution for limited timescales (1, 3, 6, 9, 12, 24, and 48 months).[5]
Inputs to SPEI datasets can include high-resolution potential evapotranspiration (PET) from the Global Land Evaporation Amsterdam Model (GLEAM) and hourly Potential Evapotranspiration (hPET). GLEAM is a set of algorithms designed to calculate actual evaporation, PET, evaporative stress, and root-zone soil moisture.[5]
^Stagge, J. H.; Tallaksen, L. M.; Xu, C. Y.; Van Lanen, H. A. (2014). "Standardized precipitation-evapotranspiration index (SPEI): Sensitivity to potential evapotranspiration model and parameters". Hydrology in a changing world. IAHS-AISH Proceedings and Reports. Vol. 363. pp. 367–373. ISBN9781907161414.
^Tirivarombo, S.; Osupile, D.; Eliasson, P. (2018). "Drought monitoring and analysis: standardised precipitation evapotranspiration index (SPEI) and standardised precipitation index (SPI)". Physics and Chemistry of the Earth, Parts A/B/C. 106: 1–10. Bibcode:2018PCE...106....1T. doi:10.1016/j.pce.2018.07.001. S2CID134507763.
