Examining the spatio-temporal evolution and characteristics of large-scale European droughts

Historical records of major droughts at continental scales are useful in contributing to improved water resources management and better understanding of hydrological processes. Droughts exhibit complex spatial and temporal variability, so an objective classification is preferable to allow comparisons to be made between different regions and seasons. This study investigates the use of threshold-based regional indices of hydrological and meteorological deficiency to characterise regional drought across Europe, and to examine the spatio-temporal evolution of large-scale droughts. Major droughts over the second half of the twentieth century have been identified using these approaches, and the 1962-64 and 1995-97 events are explored in more detail, with particular focus on the UK, through comparisons between their differing spatio-temporal evolution, temperature and pressure anomalies and the synoptic climatic conditions. It is concluded that the European droughts of 1962-64 and 1995-97 have distinctive 'signatures', and a variety of drought characteristics and developmental stages that reflect the complexity of drought evolution. Whilst the former event featured a straightforward succession of dry winters that were generally coherent in the UK and Europe, the latter was a more complicated amalgam of summer and winter deficiencies containing alternating periods when the UK was 'in phase' or 'out of phase' with Europe. These complexities potentially preclude the development of forecasting tools pending further research on the intricacies of the spatio-temporal variability of droughts.