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Precipitation-evapotranspiration index SPEI-12
Source: unofficial: test dataUpdated: 18.10.2026 · form of 01.09.2026
I.29
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Unofficial data only
Precipitation-evapotranspiration index SPEI-12
Name in the form: Standardized precipitation evapotranspiration index (SPEI)
Period
- Form 1-IK
- Unofficial
Data
Values by year
| Year | Valueindex | Source and note |
|---|---|---|
| 2021 | −1.35 | Test |
| 2022 | −0.42 | Test |
| 2023 | −0.61 | Test |
| 2024 | 0.55 | Test |
| 2025 | −0.38 | Test |
Source data
Value in Form No. 1-IK
Not filled in.
Quality
Data remarks
No remarks.
Methodology
Indicator metadata
- Definition
- A modern multi-criteria drought index used to identify the onset, duration and intensity of hydrometeorological droughts. Unlike classical indices, it takes into account not only the amount of precipitation (moisture input) but also potential evapotranspiration (moisture loss), which makes it highly sensitive to the manifestations of global warming. It is recommended by the World Meteorological Organization (WMO) as the main indicator for monitoring agricultural and hydrological drought under a changing climate.
- Calculation method
- The calculation is based on the climatic water balance for a given time step (moving intervals of one, three, six or twelve months are usually used). First, for each month the difference between total precipitation and potential evapotranspiration is calculated, the latter being computed by the Thornthwaite or Penman–Monteith method on the basis of air temperature. The resulting difference values are mathematically smoothed and transformed using a three-parameter log-logistic probability distribution to bring them to a normal distribution with a mean equal to zero. Resulting values around zero correspond to the norm, positive values indicate excess moisture, and a drop of the index below minus one signifies the onset of drought (values below minus two signal extreme drought). The indicator is calculated monthly
- Institution responsible for calculation
- Agency for Hydrometeorology of the Committee for Environmental Protection under the Government of the Republic of Tajikistan; Committee for Environmental Protection under the Government of the Republic of Tajikistan; Pyrenean Institute of Ecology (IPE-CSIC, Spain), custodian of the global SPEIbase database