Evaluating Whistler Influence on the VLF Wave Intensity in the Inner Magnetosphere

Lightning activity was shown to be one of the most significant contributors to the overall intensity of electromagnetic waves in the Earth's inner magnetosphere, especially on the nightside and at frequencies on the order of a few kilohertz. In the present study, we combine electromagnetic wave intensity measurements performed by the Van Allen Probes and DEMETER spacecraft with ground-based lightning activity observations by the World Wide Lightning Location Network (WWLLN) to evaluate this contribution in detail. Different spacecraft orbits allow us to compare measurements performed by the Van Allen Probes at various radial distances near the equatorial plane with DEMETER spacecraft measurements at low altitudes. Lightning times and locations obtained by the WWLLN then make it possible to estimate lightning activity levels corresponding to individual data points from spacecraft measurements. The difference between wave intensities measured at the times of high and low lightning activity is evaluated as a function of wave frequency, spacecraft location, and level of geomagnetic activity.