Journal of Geography, Environment and Earth Science International

Regions of the permanent ionosphere instability are identified with 24h daily global W-index maps produced from Global Ionospheric Maps of Total Electron Content, GIM-TEC, provided by Jet Propulsion Laboratory. Planetary Wp index derived from hourly W-index maps from January, 1999, to present, is used to compile Catalogue of more than 270 ionospheric storms which comprise 8% of total database, and the rest represents quiet conditions. The positive storm percentage occurrence (enhanced electron density, pW⁺) and negative storm occurrence (depleted electron density, pW^-) are analyzed in space and time showing dependence on solar activity (SA) and seasons for the global ionosphere and its adopted 240 sub-domains (of latitude bins equal to 10º in the polar regions and 20° elsewhere and 15° hourly longitude bins). A global occurrence of pW⁺ and pW^- during Wp storms follows the 11-year solar cycle with pW^- greater than pW⁺ by about 2 times at high SA and moderate SA while the opposite is observed at solar minimum when pW⁺ is greater than pW^- by about 1.2 times. The regions of enhanced positive storm activity (pW⁺»10%) are found to occur in the South America, North seashores of Europe and Russia, and between longitudes 30°W to 30°E in Antarctica. Zones of negative storms (pW^-»22%) are dominated in Antarctica. The pW⁺ and pW^- depict winter maximum of pW⁺ and summer maximum of pW^- under Wp storm conditions decreasing from high latitudes to minimum at equator throughout all seasons in the both hemispheres. While pW⁺ and pW^- reach 20-25% under the ionosphere storm conditions, the spatial occurrence of pW⁺ and pW^- comprise 6% under quiet conditions at high latitudes which testify on the persistent plasma instability in the ionosphere through more than the total cycle of solar activity.