Space‐Time Patterns of Meteorological Drought Events in the European Greater Alpine Region Over the Past 210 Years

Abstract

Droughts may have tremendous impacts on humans. However, the space‐time characteristics of droughts are not very well understood, as case studies usually focus on individual drought events. Here we investigate the spatiotemporal drought characteristics of a large sample of events over the past 210 years in the Greater Alpine Region of Central Europe. We use monthly precipitation data, and flag, for each grid point, time steps with precipitation below a 20% percentile. We then propose a new method that detects drought events by connecting the flagged elements to space‐time drought regions. In contrast to the traditional drought indices that are based on a fixed, prescribed time window, this method is able to identify droughts of different durations in an objective way. The data show multidecadal variations of drought frequency, duration, intensity, and severity, but no consistent trends over the 210 year period. The top 5% of events in terms of their severity show a shift in seasonality from winter/spring events in the late nineteenth century toward autumn events during the last decades of the twentieth century. The most severe events center either in the Northwest or in the Southeast of the region analyzed. We found no significant correlations of drought frequency, duration, intensity, and severity with the temperature increases in the past three decades. Dry springs significantly enhance temperatures during summer droughts, suggesting a soil moisture‐temperature feedback.

Contrasting biosphere responses to hydrometeorological extremes: revisiting the 2010 western Russian heatwave

“…Buermann et al (2013) showed that warmer springs going hand in hand with earlier vegetation activity negatively affect soil moisture in summer, and thereby vegetation activity. It is a general observation that warm and dry springs enhance summer temperatures during droughts, which suggests the presence of soil-moisture temperature feedbacks across seasons (Haslinger and Blöschl, 2017). In the case of the Russian heatwave 2010, soil moisture was one of the main drivers (Hauser et al, 2016), hand in hand with persistent atmospheric pressure patterns (Miralles et al, 2014).…”

Disentangling Drivers of Meteorological Droughts in the European Greater Alpine Region During the Last Two Centuries

“…The gridded precipitation data set that they are based on (Efthymiadis et al, 2006) is using station data, which is of course sparse from the beginning of the Note. Mean drought intensity and drought severity are dimensionless measures of space-time precipitation anomalies (see Haslinger & Blöschl, 2017), where drought severity is mean drought intensity times the duration; average precipitation is the observed precipitation averaged over the Greater Alpine Region divided by the duration in days, average precipitation deficit is the average precipitation divided by the climatological mean for the months under consideration; accumulated deficit is the average precipitation deficit times the duration in days.…”

“…As pointed out by Mishra and Singh (2010), it is very important to understand historical droughts on regional scales to be able to better assess future drought processes in the wake of global climate change, since drought projections are associated with considerable uncertainty (see Haslinger et al, 2016 for the GAR). Over the last two centuries no trends in meteorological droughts (precipitation deficits) have been observed in the GAR (Haslinger & Blöschl, 2017), although soil moisture droughts have increased due to enhanced potential evapotranspiration associated with increasing temperatures, solar radiation, and vegetation activity (Duethmann & Blöschl, 2018;van der Schrier et al, 2007). The results of this paper suggest that the 1860s are not likely to occur in the near future, as they were closely related to the cool climate at the end of the Little Ice Age around 1850 (Matthews & Briffa, 2005) resulting in strong anomalies of the atmospheric circulation, particularly in MAM.…”

Large‐scale heavy precipitation over central Europe and the role of atmospheric cyclone track types

“…Besides regional differences in precipitation characteristics, seasonal patterns exist (Zveryaev, , ) which are typically caused by annual variations of air temperatures, solar insolation, dominant atmospheric weather patterns and vegetation dynamics. On top of that, internal climate variability induces large variations of dry or wet conditions at decadal and inter‐annual timescales (Rimbu et al ., ; Schmidli et al ., ; Casty et al ., ; Pauling et al ., ; Masson and Frei, ; Haslinger and Blöschl, ). Hydro‐meteorological extremes are of particular relevance.…”