Measurements and Modeling of Near-Surface Radio Propagation in Glacial Ice and Implications for Neutrino Experiments

Understand

We present measurements of radio transmission in the $\sim$100 MHz range through a $\sim100$ m deep region below the surface of the ice at Summit Station, Greenland, called the firn.

• In the firn, the index of refraction changes due to the transition from snow at the surface to glacial ice below, affecting the propagation of radio signals in that region.
• We compare our observations to a finite-difference time-domain (FDTD) electromagnetic wave simulation, which supports the existence of three classes of propagation: a bulk propagation ray-bending mode that leads to so-called "shadowed" regions for certain geometries of transmission, a surface-wave mode induced by the ice/air interface, and an arbitrary-depth horizontal propagation mode that requires perturbations from a smooth density gradient.
• In the non-shadowed region, our measurements are consistent with the bulk propagation ray-bending mode both in timing and in amplitude.