European drought climatologies and trends based on a multi-indicator approach

• We present European meteorological drought climatologies for 1950–2012.
• We combined three drought indicators: the SPI, the SPEI, and the RDI.
• We obtained drought frequency, duration, and severity European trends.
• We identified drought hotspots for 1951–70, 1971–90, and 1991–2010.
• Drought variables show an increase in SW Europe, a decrease in NE Europe.

Drought is one of the most important weather-induced phenomena which may have severe impacts on different areas such as agriculture, economy, energy production, and society. From a meteorological point of view, drought can be induced and/or reinforced by lack of precipitation, hot temperatures and enhanced evapotranspiration. Starting from a multi-indicator approach, we present European-wide meteorological drought climatologies and trends for the period 1950–2012. As input data, we used precipitation and temperature data from the E-OBS (spatial resolution: 0.25° × 0.25°) gridded dataset of the European Climate Assessment and Dataset (ECA&D). Precipitation, temperature, and the derived potential evapotranspiration (PET) have been used to compute three drought indicators: the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), and the Reconnaissance Drought Index (RDI). SPI, SPEI, and RDI, calculated for 12-month accumulation period, have been rationally merged into a combined indicator and this quantity has been used to obtain drought frequency, duration, and severity for the entire Europe. We identified the following drought hotspots: Scandinavia, Eastern Europe, and Russia in 1951–1970, no particular hotspot in 1971–1990, the Mediterranean region and the Baltic Republics in 1991–2010. A linear trend analysis shows that drought variables increased in the period 1950–2012 in South-Western Europe, in particular in the Mediterranean and Carpathian regions, with precipitation decrease and PET increase as drivers. Drought variables show a decrease in Scandinavia, Belarus, Ukraine and Russia: precipitation increase is the main driver. In Central Europe and the Balkans, drought variables show a moderate increase, for the significant PET increase outbalances a not significant precipitation increase.