Linking streamflow drought to the occurrence of atmospheric circulation patterns

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Abstract
The growing use of surface water resources calls for more intense research on low flow causes and characteristics. This paper presents an investigation linking regional streamflow drought to the occurrence of atmospheric circulation patterns (CPs). Streamflow drought events of 74 basins in southern Germany were determined using the threshold level approach. The regional classification of the basins through a cluster analysis of the drought series provided the basis for the definition of a regional drought index and the following investigation of the influence of CP occurrence on drought. Frequency cross-tabulation showed several high-pressure and anticyclonic CP types to be strongly associated with streamflow drought in southern Germany. The influence of these CPs on streamflow drought was quantified using a logistic regression model. The model results revealed important regional differences concerning the time lag of the drought response and the relevant CPs.