Speaker
Description
Cosmic Ray Neutron Sensing (CRNS) is a technique to measure water content in soil or snow on the hectare scale through the measurement of epithermal neutrons above the ground.
The measurement of epithermal neutrons needs to be corrected for the change in solar modulation affecting the incoming cosmic ray flux.
In addition, the specific geomagnetic conditions of the measurement location have to be accounted for in the heliospheric correction. A possible approach is to isolate the heliospheric influence on the neutron signal and then re-localise it to a specific point on earth, which is commonly done using neutron monitor data and a simple linear relation. The re-localisation is also feasible using PARMA (PHITS-based Analytical Radiation Model in the Atmosphere) developed by Sato et al. (2015), an analytical model of particle transport simulations in the atmosphere. PARMA's input is based upon a free parameter derived from the Galactic Cosmic Ray ISO model by Matthiä et al. (2013) as such it is connected to the solar modulation. Specifically, this method is based on measurements by the Cosmic Ray Isotope Spectrometer aboard the Advanced Composition Explorer and their fit to neutron monitor data. PARMA's input calculation was adapted to use as a CRNS correction method. Then, the performance of linear correction methods and PARMA was evaluated on long term neutron monitor data.
