TY JOUR TI An approach to finding an integral characteristic of ionospheric and lightning activity from WWLLN observational data KW Lightning location KW Earth--ionosphere waveguide KW ionosphere KW lightning KW atmospheric electricity KW instrumentation/sensors JO Russian Journal of Earth Sciences AU Kudryavtsev, N.G. AU Kudin, D.V. AU Uchaikin, E.O. PY 2018 IS 18 PB Geophysical Center of the Russian Academy of Sciences