Global Distribution of Zones of Enhanced Risk for the Ionospheric Weather

Abstract

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.