Man-made climate change has made extreme events such as heatwaves, drought and heavy rainfall more frequent, a trend that experts expect to continue. In CRC 1502, which was set up by the German Research Foundation (DFG) and is being led by the University of Bonn, a research team is studying the impact on the regional climate of human-induced changes in land use and more intensive water management. ESA’s NGGM will allow the team to improve their simulations with the aid of more precise data and thus gain a better understanding of what causes droughts and floods.
More precise data for modeling drought and flooding
The researchers in CRC 1502 are investigating the extent to which human-induced changes in land use and more intensive water management are influencing the regional climate and thus unintentionally affecting the natural water and energy cycles in that region. “In the four years the CRC has been up and running, we’ve devised a linked model system that, besides the dynamics of the individual components of the Earth system, also maps how these interact with one another,” explains the CRC’s speaker, Professor Jürgen Kusche from the Institute of Geodesy and Geoinformation at the University of Bonn. In particular, the models are intended to measure humanity’s influence on the natural water cycle in a particular region, which is already being assessed using data from the GRACE and GRACE-FO satellite missions. This has enabled the team to establish, for instance, that the total volume of water in Germany is falling by around 760 million metric tons a year (see the press release (in German) at https://www.uni-bonn.de/de/neues/deutschland-verliert-durchschnittlich-760-millionen-tonnen-wasser-pro-jahr). As things stand, however, the satellites effectively lack the temporal and spatial resolution required to narrow these findings down any further to a smaller space, such as an individual federal state.
“The ESA is developing the Next Generation Gravity Mission (NGGM), which will enable mass changes to be monitored with greater temporal and spatial resolution, shorter latency times, and greater accuracy”, Dr. Ilias Daras, ESA’s Mission Scientist for NGGM, explains. “Furthermore, ESA cooperates with NASA in the framework of the „Mass Change and Geosciences International Constellation“ (MAGIC). The MAGIC satellite constellation will consist of NGGM and the NASA-DLR GRACE-C mission, where both satellite pairs will be flown with a few years of temporal overlap. NGGM and MAGIC will thus allow the CRC team to refine their models once these data become available. “NGGM’s satellites are giving us the opportunity to chart the Earth’s ever-changing water resources with an unprecedented degree of resolution and precision,” says Kusche, who is also a member of three Transdisciplinary Research Areas (TRAs) at the University of Bonn: Modelling, Matter and Sustainable Futures, and who advises ESA and NASA in the framework of the MAGIC cooperation. “This will give us an improved understanding of the causes of droughts and floods as well as the patterns of wet and dry periods that can already be observed in various climate zones.”
The interdisciplinary team, with members from fields as diverse as hydrology, meteorology, geodesy, Earth system modeling, remote sensing and agricultural economics, will use this data to validate and calibrate the climate models developed over the past four years and to examine the various scenarios for wet and dry periods. Researchers from CRC 1502 are also involved in SING (Studying the Impact of the NGGM and MAGIC Gravity missions), an ESA consortium that is already busy formulating and testing the algorithms needed for evaluating the NGGM data.
“This is a once-in-a-lifetime opportunity for us and is invaluable for our project,” says Annika Nitschke, a doctoral student at the Institute of Geodesy and Geoinformation whose post is being half-funded by ESA. She is working on the links between water and carbon cycles and on integrating the NGGM data into models.
SFB 1502 already uses various types of Earth observation data. For example, it is used to record changes in land use or vegetation parameters and to measure water levels in rivers, lakes and wetlands. From 2032 onwards, researchers expect to be able to integrate NGGM data into their models.