E1. Terrestrial and Planetary Electromagnetic Noise Environment

Co-conveners:

M. Hayakawa (Japan)

A.P. Nickolaenko (Ukraine)

C. Price (Israel)

K. Hattori (Japan)

Objectives:

This WG deals with the study on the characteristics of electromagnetic noises taking place not only in the terrestrial, but also in the planetary environment. The most well-known noise is the atmospheric radio noise from the lightning discharges (so-called sferics in a wide frequency range from ULF to VHF). Some examples of topical subjects on sferics are (1) monitoring of global lightning activity as studied by high frequency noise and Shumann resonance phenomena in the ELF band and (2) ELF transients related with the optical emissions in the mesosphere due to the lightning. Higher frequency lightning emission provides us with the information on the fine structure of lightning electrical structure, while lower frequency noise provides us with the macroscopic nature of lightning. The noise coming from the ionosphere/magnetosphere will be discussed as well; micro pulsations in the ULF range, VLF/ELF emissions and HF emissions due to the plasma instabilities in the space. Also, our recent topic is the radio emission from the lithosphere, which covers again a wide frequency range from DC to VHF (or even more). The characteristics and generation mechanisms of those effects and also the seismic effect onto the ionosphere will be discussed. Finally, the radio noise environment on other planets (like Jupiter) will be our topic as well.

The interaction of these natural noises with artificial noises due to human activity is also another subject. Power line harmonic radiation penetrates into the ionosphere/magnetosphere and induces the particle precipitation into the lower ionosphere (this is a kind of pollution of the natural environment by human activity). Also, we discuss the interaction of natural environment with human activity.