Data Correction
One important part of the data processing is to correct the signal of the CRNS to improve its accuracy. We have established that hydrogen atoms are the governing element that influence the "counting rate" of the sensor. However, hydrogen is not only present in soil moisture and there are other sources near the land surface that will have a bearing on the sensor's measurement. To improve the accuracy of the CRNS it is therfore imperative to isolate the hydrogen present in soil moisture, by removing or "correcting" for sources of unwanted hydrogen.
Schematic of CRNS footprint (IAEA)
In addition to unwanted hydrogen in the CRNS footprint, other factors can also affect the "counting rate" of the sensor, such as the intensity of cosmic-ray particles in the atmosphere. Such effects must also be taken into consideration as well.
To perform the data correction process unwanted influences on the sensor are quantified by correction factors. These utilize empirical models to define a relationship between hydrometeorological parameters and neutron counts. Currently there are four well established correction factors:
- Pressure (Zreda et al., 2012)
- Humidity (Rosolem et al., 2013)
- Incoming neutron intensity (McJannet and Desilets, 2023)
- Biomass (Baatz et al., 2015; Wahbi et al., 2018)
To understand the theory and derrivation of each of these correction factors use the links above to view the publications.