Satellite remote sensing Sun-Earth Physical relations Geoinformatics River dynamics

Whistler and trimpi research

The research of the lightning-triggered VLF-signals, the whistlers is a cheap, useful and natural tool of the investigation of the magnetosphere and the space surrounding the Earth. Our activity is taken in the following directions:

Whistler recording (on satellites and on the Earth) and analysis
Mass processing of whistlers
Whistler analysis (reseach of the fine structure, investigation of the direction of the propagation
Theoretical wave propagation models

A whistler recorded at Halley, Antarctica (British Antarctic Survey)

A new field of our interest is the analysis of lightning associated ionization enhancement regions in the upper atmosphere. Effect of such regions, so called Trimpi effect appears as a short perturbation - both in amplitude and phase - on signals of long-distance navigational VLF-transmitters.

The solution of Maxwell equations for ion-whistlers occuring in multicomponent plasma was worked out by refinement of real-whistler solutions of these equations. Proton- helium- and oxygene-whistlers were simulated by computer using this results (see figure below) and these simulations show good correlations with the similar signals recorded on spacecrafts. Besides this, the form and dynamic spectrum of whistler fragments recorded by spacecrafts were detailly investigated.

Whistler components E-W and N-S recorded in Antarctica were evaluated by matched filtering and parameter estimation. It was proved that the fine structure splitting expands wider frequency range than expected after previouns analysis.

The wavenormal directions of whistler fragments recorded on spacecraft AUREOL-3 were calculated. They occured to be in the 10-15 degree neighborhood of the geomagnetic line of force proving the quasi-longitudinal propagation.

The effect on VLF wave propagation of the particle precipitation (The Trimpi phenomena) were registered in a multiple experiment and measurement campaign at Budapest, Erd and Penc. A new measurement equipment was involved to the process.