Scientific background

Hydro-meteorological details and scientific objectives

Within the framework of the Swabian MOSES measurement campaign, scientists are investigating in particular local-scale thunderstorms associated with heavy rain and hail, large-scale heat waves and the associated droughts. Although these two types of extremes are triggered on very different temporal and spatial scales, they share several common characteristics: They are often associated with similar large-scale synoptic flow patterns such as atmospheric blocking. This flow pattern is characterized by large-scale weather patterns that hardly change over a longer period of time, sometimes even several weeks, and thus suppress the flow regime typical for the mid-latitudes (westerly wind drift). Affected regions can thus experience weather that differs significantly from the expected conditions for a longer period of time.

As a result, precipitation may be absent for weeks, and instead dry and warm air may be continuously transported the affected regions. Often, such heat waves are ended by the widespread occurrence of severe thunderstorms. These thunderstorms have a high potential to bring associated phenomena, such as extremely heavy rain and flash flooding, large hail, or convective strong wind gusts that can reach hurricane force. The frequency and intensity of both heat waves and severe thunderstorms have increased considerably in recent years due to climate change. In the study region in Baden-Württemberg, they represent the natural hazards with highest negative impacts: Thunderstorms cause the highest share of financial damage, heat waves claim the most lives.

With the highly industrialized Neckar valley and the open landscape of the Swabian Alb, the study area represents a unique landscape and settlement area that is ideally suited for the implementation of a combined and coordinated field experiment. The terrain has a large altitudinal gradient, the soil types change significantly over short distances, and the river catchments are rather small. The study area is one of the regions with the highest exposure to severe thunderstorms in Germany, but is also frequently affected by severe heat waves, the effects of which vary due to spatial differences in terrain characteristics and vegetation.

The approach of MOSES to reproduce and analyse the event chains of hydro-meteorological extremes aims on one hand at a better understanding of the mechanisms and processes decisive for the triggering and intensification of the events, on the other hand at a detailed investigation of their impacts and interactions with all their facets.

Information on the measurement systems used at Swabian MOSES can be found here.

i André Künzelmann (UFZ)
i Prof. Dr. Claudia Schütze (UFZ)
i Dr. Jannik Wilhelm (IMK-TRO)
i Dr. Susanna Mohr (IMK-TRO)