Speaker
Description
CRNS estimate the soil moisture by measuring fast and epithermal neutrons generated by cosmic rays in the atmosphere. Since hydrogen in water mod- erates the neutrons, wetter soils reduce neutron counts. After calibration with local samples, the neutron signal is converted into soil water content, representing an area of several hundred meters and a depth of 10–30 cm. However, these measurements need to be corrected for the incoming neutron flux changes caused by the cosmic ray flux variations normally measured by the Jungfraujoch Neutron Monitor (NM).
Since mid 2024 a CRNS has been installed in Kiel close to the Kiel NM. The latter is a measure of the incoming cosmic ray induced neutron environ- ment and is used to correct the CRNS data in order to determine the soil moisture in the surrounding area of the system. The fact that the CRNS and the NM are at the same location allows a unique insight into the correlation of both measurements. Since both count rates are expected to decrease during Forbush Decreases (FDs) we can investigate their correlation during all FDs observed from mid 2024. In contrast, no correlation is expected during the occurrence of rain events. The analysis has been repeated utilizing NMs that are located at different locations (e.g. Jungfraujoch) in order to estimate the uncertainties of the above analysis.
