Soil moisture drought in Europe: a compound event of precipitation and potential evapotranspiration on multiple timescales

AbstractCompound events are extreme impacts that depend on multiple variables that need not be extreme themselves. In this study, we analyse soil moisture drought as a compound event of precipitation and potential evapotranspiration (PET) on multiple timescales related to both meteorological drought and heat waves in wet, transitional and dry climates in Europe during summer. Drought indices that incorporate PET to account for the effect of temperature on drought conditions are sensitive to global warming. However, as evapotranspiration (ET) is moisture limited in dry climates, the use of such drought indices has often been criticised. We therefore assess the relevance of the contributions of both precipitation and PET to the estimation of soil moisture drought. Applying a statistical model based on pair copula constructions to data from Fluxnet sites in Europe, we find at all sites that precipitation exerts the main control over soil moisture drought. At wet sites PET is additionally required to explain ...