Modeling ionospheric propagation of low frequency signals for remote sensing purposes using charge density profiles

The use of powerful low or very low frequency (LF/VLF) transmitter signals (mainly in the range 15-60 kHz) is a well established technique for remote sensing of the lower ionosphere. Standard tools for calculating the the world wide propagation conditions - like the Long Wave Propagation Capability (LWPC) code - usually rely on default procedures for modeling the day-night transition conditions that do not map reality sufficiently for modeling purposes, especially with regard to timing and shape of the terminators. We propose an improved method to cover with these problems by making use of the possibility to introduce charge density profiles into the LWPC that vary appropriately over the day-night cycle and additionally can model disturbances caused by forcing of the lower ionosphere from above (X-rays, particle precipitations) and below (atmospheric waves).