Hotspots for warm and dry summers in Romania

In: Natural hazards and earth system sciences: NHESS, Band 22, Heft 4, S. 1347-1369

Open Access

Abstract

Abstract. The combined effect of hot and dry extremes can have disastrous consequences
for society, the economy, and the environment. While a significant number of
studies have been conducted regarding the variability of the individual hot
or dry extremes in Romania, the evaluation of the combined effect of these
extremes (e.g., compound effect) is still lacking for this region. Thus, in
this study, we have assessed the spatiotemporal variability and trends of
hot and dry summers in Romania, between 1950 and 2020, and we have analyzed
the relationship between the frequency of hot summers and the prevailing
large-scale atmospheric circulation. The length, spatial extent, and
frequency of heat waves (HWs) in Romania present decadal variations, with the
rate of increase being accelerated after the 1990s. The smallest number of
HWs was observed between 1970 and 1985, while the highest number of HWs has
been recorded over the last 2 decades (i.e., 2001–2020). The hottest
years, in terms of heat wave duration and frequency, were 2007, 2012, 2015,
and 2019. One of the key drivers of hot summers, over our analyzed region,
is the prevailing large-scale circulation, featuring an anticyclonic
circulation over the central and eastern parts of Europe and enhanced
atmospheric blocking activity associated with positive temperature anomalies
underneath. The results from this study can help improve our understanding
of the spatiotemporal variability of hot and dry summers over Romania, as
well as their driving mechanisms, which might lead to a better predictability
of these extreme events in the region.