GDO Standardized Precipitation Index ERA5, 9-month accumulation period (SPI-9) (version 1.0.0)

Description

The 9-month Standardized Precipitation Index (SPI-9) is a meteorological drought indicator to monitor precipitation anomalies over 9-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, 9-month accumulation period (SPI-9) (version 1.0.0). European Commission, Joint Research Centre (JRC) [Dataset] PID: http://data.europa.eu/89h/3e0368e9-e55a-4d6e-bcbf-296de8e43578

Keywords

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

Data access

Data Download Service URL

Use conditions: European Commission reuse notice
Access conditions: No limitations

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

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/3e0368e9-e55a-4d6e-bcbf-296de8e43578
Popularity