A Cosmic-Ray Neutron Probe for Intermediate-Scale Estimates of Soil Moisture at the T.W. Daniel Experimental Forest
Location
ECC 201/203 & 205/207
Event Website
http://water.usu.edu/
Start Date
4-9-2013 6:05 PM
End Date
4-9-2013 6:15 PM
Description
The cosmic-ray neutron probe (CRNP) provides intermediate-scale (~700 m diameter circle, 35 ha) area-average soil moisture measurements. A CRNP, whose footprint covers the entire T.W. Daniel Experimental Forest instrumented site, was installed in August 2011 as part of the COsmic-ray Soil Moisture Observing System (COSMOS). Independent soil moisture measurements reveal CRNP is more sensitive to near surface soil moisture (0-10cm) than deeper layers. The CRNP response to summer-time soil moisture was compared with the TWDEF soil moisture measurement network containing 108 time-domain transmission (TDT) water content sensors. We also employed the Hydrus-1D model to numerically simulate soil moisture including the top 10 cm of the soil moisture profile. Comparison of these two estimates with CRNP revealed that the spatially averaged point measurements of soil moisture were less well correlated with cosmic-ray neutron counts during rainfall events that wetted the near-surface, not reaching the sensors at 10 cm. Simulations of near-surface soil moisture using Hydrus-1D showed improved correlation with CRNP response to precipitation events that trigger increased surface soil moisture. The sensitivity to near-surface soil moisture makes CRNP a powerful indicator of soil surface water status and could potentially be used to interpret soil water fluxes at this intermediate scale.
A Cosmic-Ray Neutron Probe for Intermediate-Scale Estimates of Soil Moisture at the T.W. Daniel Experimental Forest
ECC 201/203 & 205/207
The cosmic-ray neutron probe (CRNP) provides intermediate-scale (~700 m diameter circle, 35 ha) area-average soil moisture measurements. A CRNP, whose footprint covers the entire T.W. Daniel Experimental Forest instrumented site, was installed in August 2011 as part of the COsmic-ray Soil Moisture Observing System (COSMOS). Independent soil moisture measurements reveal CRNP is more sensitive to near surface soil moisture (0-10cm) than deeper layers. The CRNP response to summer-time soil moisture was compared with the TWDEF soil moisture measurement network containing 108 time-domain transmission (TDT) water content sensors. We also employed the Hydrus-1D model to numerically simulate soil moisture including the top 10 cm of the soil moisture profile. Comparison of these two estimates with CRNP revealed that the spatially averaged point measurements of soil moisture were less well correlated with cosmic-ray neutron counts during rainfall events that wetted the near-surface, not reaching the sensors at 10 cm. Simulations of near-surface soil moisture using Hydrus-1D showed improved correlation with CRNP response to precipitation events that trigger increased surface soil moisture. The sensitivity to near-surface soil moisture makes CRNP a powerful indicator of soil surface water status and could potentially be used to interpret soil water fluxes at this intermediate scale.
https://digitalcommons.usu.edu/runoff/2013/AllPosters/7