DATASET

GDO Standardized Precipitation Index ERA5, 6-month accumulation period (SPI-6) (version 1.0.0)

Collection: DROUGHT : Drought Observatories datasets 

Description

The 6-month Standardized Precipitation Index (SPI-6) is a meteorological drought indicator to monitor precipitation anomalies over 6-month accumulation periods and is a proxy indicator for medium-term impacts, for example reduced stream flow and reservoir storage. This indicator is calculated with one month total precipitation accumulation period (SPI-1), derived from the fifth generation ECMWF reanalysis for the global climate and weather ERA5 (https://confluence.ecmwf.int/display/CKB/The+family+of+ERA5+datasets) hourly precipitation data; using a reference period between the year 1991 and 2020. The SPI represents precipitation anomalies at a given location and time, as the deviation from the long-term mean in a standard-normal distribution, with more negative values representing a more severe drought. SPI is calculated by comparing the observed total precipitation amounts for an accumulation period of a number of months, indicated by a number following SPI-, with the long-term “climatological” rainfall distribution for that same period of the year, derived from historical rainfall records in a specific reference period. A given accumulation period corresponds to different potential impacts of a drought, with shorter accumulation periods generally representing fast-changing aspects of the water system such as surface soil moisture and flow in small rivers, and longer accumulation periods representing slower changing aspects of the water system such as groundwater and baseflow in larger rivers. However, the exact relationship between accumulation period and impacts depends on the natural environment (e.g. geology, soils) and human interference (e.g. irrigation). Details on the calculation of the SPI are given in the indicator factsheet.

Contact

Email
Alfred.DE-JAGER (at) ec.europa.eu

Contributors

  • European and Global Drought Observatories, EDO

How to cite

European Commission, Joint Research Centre (JRC) (2024): GDO Standardized Precipitation Index ERA5, 6-month accumulation period (SPI-6) (version 1.0.0). European Commission, Joint Research Centre (JRC) [Dataset] PID: http://data.europa.eu/89h/922267ae-6faf-475e-a97b-2974c6596277

Keywords

CEMS Copernicus Drought ECMWF ERA5 European Drought Observatory (EDO) Global Drought Observatory (GDO) Precipitation Precipitation Anomaly SPI

Data access

Data Download Service URL
URL 

Publications

Publication
The relationship of drought frequency and duration to time scale.
McKee, T.B., N.J. Doesken and J. Kleist. 1993. The relationship of drought frequency and duration to time scale. In: Proceedingsof the Eighth Conference on Applied Climatology, Anaheim, California, 17–22 January 1993. Boston, American Meteorological Society, 179–184
URL 

Geographic areas

World

Spatial coverage

Type Value
GML
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GML
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WKT
POLYGON ((-180 90, 180 90, 180 -90, -180 -90, -180 90))

Temporal coverage

From date To date
1982-01-01 N/A

Additional information

Published by
European Commission, Joint Research Centre
Created date
2024-03-25
Modified date
2024-03-26
Issued date
2024-03-25
Landing page
https://edo.jrc.ec.europa.eu/tumbo/gdo/map/ 
Language(s)
English
Data theme(s)
Environment
Update frequency
monthly
Identifier
http://data.europa.eu/89h/922267ae-6faf-475e-a97b-2974c6596277
Popularity