Spatiotemporal variability of meteorological drought in Romania using the standardized precipitation index (SPI)

摘要

This study addresses the spatial and temporal variability of meteorological drought in Romania based on a standardized precipitation index (SPI) analysis over the period 1961-2010. The 1- and 3 mo SPI values from 124 meteorological stations were used to examine the duration, magnitude, intensity, and frequency of the drought spells. Empirical orthogonal function analysis supported the investigations on the variability of the SPI values both in time and space, and this was framed in relation to mesoscale patterns of meteorological variables like air pressure, humidity and temperature. The role of?the North Atlantic Oscillation in the winter precipitation deficit, and the possible influence of the Atlantic Multidecadal Oscillation on summer droughts are revealed. The study indicates that large-scale atmospheric circulation is the major drought driver in Romania in winter, while thermodynamic factors (such as air temperature and humidity) are the major drivers in summer. The Carpathian mountain chain is the secondary regional factor influencing SPI spatial variability, triggering differences between the intra-Carpathian and extra-Carpathian regions in winter time.