Nonlinear heating effects on the transionospheric propagation of lightning-radiated sferics

Abstract:

It is well-known that the energetic processes associated with a lightning return stroke can significantly modify the overlying ionosphere, producing fantastic ionospheric phenomena known generically as transient luminous events (TLEs). The modifications to the ionospheric conductivity in turn affect the way lightning-radiated impulses, known as radio atmospherics (sferics), propagate to near-Earth space. The whistler waves that successfully couple to the magnetosphere can have an important impact on the Earth’s radiation belts, for example. This study compares the transionospheric propagation of a lightning-radiated sferic simulated using unmodified ambient ionospheric conditions (using a linear FDTD analysis) to that simulated using lightning-modified ionospheric conditions (using a non-linear FDTD analysis). We present the differences between the simulations as a function of altitude and provide a physical explanation for the observed differences.