Isotopes & Cosmic-ray

Isotopes

The stable isotopes of water (oxygen-18 and deuterium) are used as tracers for quantifying fluxes across hydrological compartments, including flow in the vadose zone (WP3) and groundwater-surface water interactions (WP4 and WP5).

Danish Network of Isotopes in Precipitation (WP10)
A regional network of precipitation collectors has been established in 2012 with the objective of obtaining time series of stable isotopes in precipitation across the Skjern River Catchment. The network is supported by the International Atomic Energy Agency (IAEA) and is the Danish part of the Global Network of Isotopes in Precipitation (GNIP).

Cosmic-ray

Cosmic-ray neutrons can be used to measure water at and near the land surface, mainly soil water, snow and water in and on vegetation. The cosmic-ray method takes advantage of the inverse relation between the intensity of cosmogenic neutrons in air above land surface and soil moisture. With a unique horizontal footprint of hectometers and a vertical footprint of decimeters, cosmic-ray measurements average out small-scale variations in soil moisture and provide an area-average, representative measure of soil moisture. The cosmic-ray method has been adopted widely and many new applications are being developed. Examples include measuring snow water equivalent and vegetation water equivalent, determining infiltration rates and unsaturated hydraulic conductivity of soils, mapping soil moisture over large areas using mobile cosmic-ray probes, measuring rainfall rates, and measuring the amount of snow and liquid water on canopy.


HOBE has established close collaboration with leading international scientists within application of cosmic ray instrumentation for measuring soil moisture, forest interception and biomass. Data collected from the HOBE sites (Gludsted, Voulund, and Harrild Hede) as well as sites in TERENO and USA is currently being analyzed. We trust that HOBE can make significant contributions to the further development of the cosmic ray technology.