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Torrential Rain in Place of Sunshine

Measuring campaign investigating drought instead records heavy rain

Copyright: pixabay

Things never turn out quite the way you expect. On 20 May, a group of researchers began a measuring campaign in Upper Bavaria, Germany, within the scope of the MOSES Helmholtz initiative. Although they were prepared for extreme weather situations, what happened was rather different to what they were expecting. The researchers had planned to obtain insights into the effects of heatwaves and droughts, for example how exactly dryness affects soil, vegetation, and air quality. Such observational data help refine climate models and ensure better protection for the population. But instead of high temperatures and a lack of water, the low-pressure system Axel led to the exact opposite: lots and lots of rain. The study region received as much precipitation within a short time as it usually does over a month.

This unexpected weather situation demanded lots of spontaneity from the researchers on site. But the torrential rain also meant that the team, which includes scientists from Forschungszentrum Jülich, were able to prove the particular strengths of their approach. A flexible sensor and deployment concept, for example, permitted them to adapt the original setup at short notice. The measuring programme can thus be conducted as planned until mid-June. However, its focus now is no longer on the effects of drought but those of heavy rain, as well as the processes that occur before, during, and after such extreme events. For the measuring campaign, a series of new sensors are being deployed for the first time.

Mobile Messstation­
Copyright: KIT / Kevin Wolz

One such sensor is designed to determine soil moisture by measuring cosmic radiation: here, cosmic ray sensors are used to count the neutrons in the surrounding air. “Neutron intensity permits us to draw conclusions on soil moisture,” says Dr. Heye Bogena from Forschungszentrum Jülich’s Institute of Bio- and Geosciences (IBG-3). “In the event of severe drought, these data naturally play a large role for vegetation in particular. The information can be used by farmers to control irrigation, for example. In the event of too much rain, on the other hand, it makes it easier to recognize when the soil cannot absorb any more water,” Bogena explains. With this knowledge, potential dangers posed by floods can be more easily predicted and relevant warnings issued.

Another measuring module being used for the first time by IBG-3 during the MOSES test campaign in Upper Bavaria is MoLEAF (pictured above), a mobile land ecosystem atmosphere flux module which permits the isotope-specific detection of CO2 and water-vapour fluxes between the ecosystem and the atmosphere. The data recorded in this way allows the researchers to resolve these important gas fluxes into their individual components, i.e. to separately quantify their individual component fluxes (photosynthesis/respiration, evaporation/transpiration) and thus determine which of these reacts more strongly to extreme events. This information can be used to improve models predicting the impact of climate change on land ecosystems and their effects on the atmosphere.

While the cosmic ray rover, a mobile neutron detector, and the isotope MoLEAF module were impervious to the torrential rain, another measuring instrument needed to take a break at first, due to the weather: “We had to delay flying the drone by two days,” explains Prof. Nicolas Brüggemann (IBG-3). “However, the bigger problem was to obtain a flight permit for longer periods of time.” The drone, equipped with new sensors such as thermal-imaging and multispectral cameras, was another first for the measuring campaign.

Copyright: Zeeman

The MOSES measurements are part of the intensive measurement campaign ScaleX 2019. Headed by Campus Alpin at Karlsruhe Institute of Technology (KIT) in Garmisch-Partenkirchen, the campaign involves setting up a collection of instruments for a limited time in the Bavarian Prealps. It unites universities and scientific institutions – including Forschungszentrum Jülich – from all over Germany. The measuring campaign aims to investigate the effects of climate change, for example the increase in extreme weather events.

More information:

MOSES-Website (englisch)


Institute of Bio- and Geosciences (IBG-3)