Integration of soil moisture measurements into the observation network of the German Meteorological Service – the project IsaBoM

As many other European countries, Germany has been affected by an increasing number of both drought and flood events in the last couple of years that had considerable negative impacts on the agricultural and forestry sector. These events led to an increasing information demand of stakeholders, practitioners and the general public on critical variables such as soil moisture.  Area-wide information on soil moisture is most often derived indirectly from hydrological model simulations, one of them being DWD’s soil moisture viewer which is based on the soil-vegetation-atmosphere-model AMBAV. Besides model-based soil moisture information, which is strongly influenced by model assumptions and parameterisation, a number of institutions started to build-up local soil moisture observation networks, such as the TERENO network, that also provide in-situ observations of soil moisture states. However, a nationwide observation network for (standardised) soil moisture observations is still lacking in Germany.

The project IsaBoM (“Integration of standardised and automatized soil moisture measurements in the DWD observation network”), an internal project of the German Meteorological Service (DWD), strives to establish the technical and scientific basis for introducing standardised soil moisture observations in DWD’s operational meteorological observation network. This includes e.g. the choice of suitable sensors and measurement protocols, calibration procedures for selected sensors, quality-control measures and establishing data flow and automated data provisioning. The final goal is to equip about 25 stations throughout Germany with cosmic-ray neutron sensing (CRNS)-devices and in-situ profile measurements of soil moisture where the chosen locations should provide a representative subset in terms of soil properties and climatic conditions. Here we present the overall network design as well as first comparisons between soil moisture data obtained by different CRNS-sensors at two sites that have a broad range of complementary agrometeorological measurements in place that facilitate a thorough interpretation of the results.