High resolution global standardized drought indices

The dataset consists of the standardized precipitation (SPI) and the standardized precipitation evapotranspiration index (SPEI) index with a 30 arcsec (~1km) horizontal resolution. Data for precipitation rates (pr) and potential evapotranspiration (pet) are taken from CHELSA V2.1 (https://doi.org/10.16904/envidat.228.v2.1). Both data sets are monthly time series from 1980 to 2018 at 30 arcsec. and have the unit of kg m-2 month-1. SPEI is a more reliable measure of drought than SPI as it additionally considers the effect of potential evapotranspiration. Potential evapotranspiration (pet) is the amount of water per area per time that can evaporate at the soil surface or be transpired by plants in absence of water supply limitations. SPEI effectively estimates for a given location how the climatic water balance, i.e., the difference between precipitation rate (pr) and potential evapotranspiration (pet), relates to the long-term mean. Here, pet was calculated with the Penman-Montheith approach, assuming surface conductance of a reference crop of 12 cm height following the definition of the Food and Agriculture Organization of the United Nations (FAO), originating from CHELSA-BIOCLIM+ database (https://www.doi.org/10.16904/envidat.332). To obtain global time series of SPEI, in each pixel the frequency distribution of water balance estimates (pr-pet) is approximated with a log-logistic probability distribution function. We calculate monthly SPEI using a 12-month memory and approximate the parameters of the log-logistic probability distribution based on the time series from 1980-2018. Such a 12-month time window is suitable to capture long-term drought events that are long enough to impose substantial impacts on agriculture, hydrology, and ecosystems while ones at shorter time scales would be more appropriate to detect short-term drought. For each month, SPEI is calculated considering the respective water-balance value and the values of the eleven preceding months. Here we use SPEI-12 in December to represent the overall water-balance condition of the respective year. The resulting SPEI data has a horizontal resolution of 130 arcsec (~1km). The calculation of SPI and SPEI is done in R with the package SPEI (https://www.doi.org/10.32614/CRAN.package.SPEI).

Funding Information:

This work was supported by:
  • Swiss Federal Research Institute WSL - Extremes (link) (Grant/Award: EMERGE)

Related Datasets

https://doi.org/10.16904/envidat.228.v2.1 https://doi.org/10.16904/envidat.332

Related Publications

Chen, L., Brun, P., Buri, P., Fatichi, S., Gessler, A., McCarthy, M., Pelliciotti, F., Stocker, B., Karger, D.N. (2025) Global increase in the occurrence and impact of megadroughts. Science https://doi.org/10.1126/science.ado4245

Citation:

Chen, Liangzhi; Brun, Philipp; Buri, Pascal; Fatichi, Simone; Gessler, Arthur; McCarthy, Michael James; Pellicciotti, Francesca; Stocker, Benjamin; Karger, Dirk Nikolaus (2024). High resolution global standardized drought indices. EnviDat. doi:10.16904/envidat.530.

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Metadata

Field Values
DOI 10.16904/envidat.530
Publication State Published
Authors
  • Email: liangzhi.chenfoo(at)wsl.ch Given Name: Liangzhi Family Name: Chen Affiliation: Swiss Federal Institute for Forest, Snow and Landscape Research WSL; Birmensdorf, 8093, Switzerland
  • Email: philipp.brunfoo(at)wsl.ch ORCID: 0000-0002-2750-9793 Given Name: Philipp Family Name: Brun Affiliation: Swiss Federal Institute for Forest, Snow and Landscape Research WSL
  • Email: pascal.burifoo(at)wsl.ch Given Name: Pascal Family Name: Buri Affiliation: Swiss Federal Institute for Forest, Snow and Landscape Research WSL; Birmensdorf, 8093, Switzerland
  • Email: ceesimofoo(at)nus.edu.sg ORCID: 0000-0003-1361-6659 Given Name: Simone Family Name: Fatichi Affiliation: Department of Civil and Environmental Engineering, National University of Singapore; Singapore, 117576, Singapore
  • Email: arthur.gesslerfoo(at)wsl.ch ORCID: 0000-0002-1910-9589 Given Name: Arthur Family Name: Gessler Affiliation: Swiss Federal Institute for Forest Snow and Landscape Research WSL, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
  • Email: michael.mccarthyfoo(at)wsl.ch Given Name: Michael James Family Name: McCarthy Affiliation: Swiss Federal Institute for Forest, Snow and Landscape Research WSL; Birmensdorf, 8093, Switzerland
  • Email: francesca.pellicciottifoo(at)ist.ac.at ORCID: 0000-0002-5554-8087 Given Name: Francesca Family Name: Pellicciotti Affiliation: Institute of Science and Technology Austria, ISTA; Klosterneuburg, 3400, Austria
  • Email: benjamin.stockerfoo(at)unibe.ch ORCID: 0000-0003-2697-9096 Given Name: Benjamin Family Name: Stocker Affiliation: Institute of Geography, University of Bern; Bern 3012, Switzerland
  • Email: dirk.kargerfoo(at)wsl.ch ORCID: 0000-0001-7770-6229 Given Name: Dirk Nikolaus Family Name: Karger Affiliation: Swiss Federal Institute for Forest, Snow and Landscape Research WSL; Birmensdorf, 8093, Switzerland
Contact Person Given Name: Dirk Family Name: Karger Email: dirk.kargerfoo(at)wsl.ch
Subtitles
Publication Publisher: EnviDat Year: 2024
Dates
  • Type: Created Date: 2018-12-31 End Date: 2018-12-31
Version 1.0
Type dataset
General Type Dataset
Language English
Location Switzerland
Content License Creative Commons Attribution    [Open Data]
Last Updated January 28, 2025, 13:46 (UTC)
Created July 18, 2024, 11:01 (UTC)

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