Drought index
The drought index is a standardized measure of the severity and spatial extent of drought in climatic regions such as Europe. The index is an important tool for identifying, monitoring and evaluating droughts.
The availability of water in the form of precipitation is the key variable when assessing drought, on which the first generation of drought indices is based. They are known as Meteorological Drought Indices . Their calculation is based on the current and historical precipitation data and determines the deviation from an average value.
The water storage capacity of the soil can compensate for precipitation deficits, which is why this parameter is also included in the calculations of the further developed hydrometeorological drought indices . These include hydrological parameters such as the runoff, evaporation, soil moisture and the amount of snow.
Different indices are used to indicate the degree of drought.
Drought indices SPI and GPCC-DI
The “Standardized Precipitation Index” (SPI) is a measure of the drought that is based on precipitation data and thus only records the meteorological influence. The index was developed by the Colorado Climate Center , USA.
Another factor that determines drought is soil moisture and the associated evaporation. The hydrological drought can last longer because the soil can remain dry after a period of little rain has ended. The drought index was expanded accordingly to include evaporation and changed to a standardized precipitation evaporation index ("Standardized Precipitation Evaporation Index"). The new index is called "Global Precipitation Climatology Center Drought Index" - GPCC-DI and is used for European drought monitoring.
The German Meteorological Service - Regional Climate Monitoring has published bi-monthly maps for Europe about the strength and spatial extent of drought according to the GPCC-DI since January 2016.
Drought Monitor Germany
The Drought Monitor Germany of the Helmholtz Center for Environmental Research - UFZ provides daily information on the state of soil moisture. The maps show the drought status of the total soil and the topsoil, which reacts more quickly to short-term precipitation events, as well as the plant-available water in the soil.
- Drought monitor total floor , approx. 1.8 m
- Drought monitor topsoil, up to 25 cm
- Plant-available water, up to 25 cm
Data from about 2500 weather stations of the German Weather Service are used and transferred to the 4 km grid of the Germany maps. The soil moisture in Germany is usually higher in winter than in summer. This is due to the very low level of evaporation in winter and the higher intensity of precipitation in summer. (This can be taken from the annual course of soil moisture in 2018 in the adjacent picture.)
Palmer Drought Index
Another Hydrometeorological drought index is developed by Wayne C. Palmer in 1965 in the US Palmer Drought Index (Palmer Drought Index - PDSI), which in addition to the meteorological parameters and elements taken into account the water cycle. It is the most common drought index in the United States.
Since 2005 is the UCL Department Space and Climate Physics Palmer Drought Index and monthly for the entire world in the form of Global Drought Monitor published ( "Global Drought Monitor").
Web links
- Global Drought Information System , UCL Department Space and Climate Physics
Individual proof
- ^ Dürre-Index , Climate Service Center Germany, Helmholtz-Zentrum Geesthacht.
- ↑ Description Page Standardized Precipitation Index (SPI) for Global Land Surface , additional text.
- ↑ Climate maps of the drought index , German Weather Service - Regional Climate Monitoring.
- ↑ RCC Node-CM Product Description , Version 3.1 (May 2016, last update: January 12, 2018).
- ↑ UFZ Drought Monitor Germany , Helmholtz Center for Environmental Research - UFZ.
- ↑ Wayne C. Palmer: Meteorological drought , Ed .: US Department of Commerce & Office of Climatology, Weather Bureau. Research paper no.45, February 1965.
- ↑ Mark Saunders: Global Drought Monitor and European Wind Damage Forecasts Launched , UCL Department Space and Climate Physics, January 4, 2006.