Karlsruhe Institute of Technology: Research association starts measurement campaign on hydro-meteorological extremes in the Swabian Alb area
Extreme weather events such as strong thunderstorms, hail or heat waves have increased in Germany in recent years and in some cases cause major economic and infrastructural damage. The complex physical processes that take place when these weather events occur are being investigated by the Helmholtz initiative MOSES, in which the Karlsruhe Institute of Technology (KIT) is also involved. The aim of the measurement campaign “Swabian MOSES”, which is now starting and coordinated by KIT, is to holistically investigate the causes, effects and interactions of hydro-meteorological extremes. In the study area in Baden-Württemberg, both thunderstorms and periods of heat and drought occur frequently.
In order to investigate the effects of meteorological and hydrological extremes on the long-term development of earth and environmental systems, nine research centers of the Helmholtz Association are building the mobile and modular observation system MOSES (Modular Observation Solutions for Earth Systems), which should be fully operational by 2022 . Test campaigns are an important part of this development work, because the new measuring systems in mobile use must be tested, further developed and coordinated with one another. Two of these campaigns on different questions and in different study areas have so far been planned for the year 2021 – in the area of the Swabian Alb and on the Elbe.
The “Swabian MOSES”measurement campaign will start in May in the Swabian Alb and Neckar Valley in Baden-Württemberg, which is expected to run until mid-September and will be coordinated by KIT. The focus is on two hydro-meteorological extremes – drought and heavy precipitation. The accumulation of dry periods of several weeks in the years 2018 to 2020 meant that the groundwater level sank to a historic low last year and many rivers had pronounced low water – with considerable restrictions for shipping, irrigation and power plant cooling.
“Due to its complex topography and geographical location, the study region is particularly often affected by severe thunderstorms,”says Professor Michael Kunz from the Institute for Meteorology and Climate Research – Department of Tropospheric Research (IMK-TRO), one of the coordinators of the project. “A hailstorm in our study area in July 2013, for example, in which hailstones with a diameter of up to 10 centimeters were observed, caused damage of around one billion euros.”Cause areas that not only lead to considerable damage, but also to massive sediment and pollutant transport in bodies of water.
In addition to the lead Institute for Meteorology and Climate Research (IMK) of KIT, the Helmholtz Center for Environmental Research (UFZ) from Leipzig, Forschungszentrum Jülich (FZJ), the University of Hohenheim, the Eberhard Karls University of Tübingen and the Technical University are involved with various measurement systems Braunschweig, the Helmholtz Center Potsdam – German Research Center for Geosciences (GFZ), the German Aerospace Center (DLR) and the German Weather Service (DWD).
Effects of thunderstorms on the atmosphere, climate and ecosystems
KIT uses its mobile observatory KITcube. “The KITcube provides detailed information about the state of the atmosphere during the formation and development of thunderstorms, the first focus of the measurement campaign,”said Dr. Andreas Wieser, scientific director of KITcube. This is achieved through the combination of the most modern remote sensing devices and a large number of local measurement systems distributed in the measurement area.These include a state-of-the-art cloud radar, precipitation radar, a network of lidars that can be used to record atmospheric air currents with the help of lasers, weather balloons and weather stations. A new type of mobile cloud chamber at KIT measures the amount of ice-forming particles that are jointly responsible for the formation of precipitation and hail in thunderclouds.
During the campaign at the Land-Atmosphere Feedback Observatory (LAFO), the University of Hohenheim operates its network of soil moisture and energy balance stations for measuring energy, moisture and CO2 flows near the ground, as well as several modern lidar remote sensing devices that simultaneously distribute the Measure humidity, temperature and wind as well as their fluctuations in the atmosphere.
The scientists at Forschungszentrum Jülich let balloon probes rise to a height of 35 kilometers in order to determine, among other things, how thunderstorms will affect the climate in the long term. The DWD carries out additional balloon ascents at the Stuttgart-Schnarrenberg location, so that information about important weather parameters can be obtained in advance of thunderstorms. Two research aircraft from the Technical University of Braunschweig collect data in the vicinity of thunderstorms for three weeks in June and July. Measuring devices integrated on board allow the determination of energy and moisture fluxes within the atmosphere. A lidar developed by KIT is also installed, which records vertical wind profiles along the flight path, which enables conclusions to be drawn about the flow in the areas where thunderstorms arise.
Researchers from the University of Tübingen and the UFZ are investigating the influence of heavy rain and flooding on the substance loads of flowing waters. A special focus is on the dissolved and particle-bound pollutants that get into water bodies through heavy rain from various sources, and the resulting toxicity for the aquatic ecosystem. The aim of the investigations is to record the material input paths in hydrologically different catchment areas, which differ in land use and degree of urbanization, and to record the water quality. Some of the samples are examined at the UFZ for organic pollutants and their mixed toxicity. In cooperation with KIT, the researchers are also investigating the exchange of greenhouse gases between rivers and the atmosphere.
Development of periods of heat and drought in the region
In order to record the effects of heat and drought stress on agricultural areas in the Swabian Alb, KIT is setting up measuring stations at several locations that quantify the energy and material exchange between the affected ecosystems and the atmosphere. The GFZ supplements these measurements from the air using appropriate sensors attached to drones. In addition, the KIT installs several aerosol measuring devices in order to research connections between their distribution and periods of heat and drought.
The UFZ scientists investigate the dynamics of soil moisture as a central control variable for the runoff of rainwater and for the development of drought. For this purpose, the UFZ is installing mobile, wireless sensor networks during the measurement campaign, which measure the soil moisture and temperature at different depths. An all-terrain vehicle with specially developed neutron sensors (Cosmic Ray Rover) is also used to observe large-scale variations in soil moisture. DLR also records near-surface soil moisture with radar aircraft measurements. To do this, the researchers use innovative mapping methods and test new algorithms. To penetrate the ground, they use long wave electromagnetic waves, which show a characteristic signal depending on the soil moisture and the vegetation. The results are also used to compare the various measurement methods with regard to their accuracy.