F2 IONOSPHERIC EFFECT ON INTENSE GEOMAGNETIC STORM ASSOCIATED WITH DIFFERENT DRIVERS: MAGNETIC CLOUD AND COMPLEX EJECTA.

Abstract

The F2-region response to the intense geomagnetic storm was studied using six (6) ionospheric stations ranging from high to low latitude. The onset of the geomagnetic storms is used in the method of classification of variation of electron density. The increases or decreases of maximum electron density (NmF2) in the storm onset were classified into four types: positive or negative storm phase, positive storm followed by negative storm and negative storm followed by positive storm. The criterion used enables us to properly identify whether or not plasma is redistributed owing to sunrise effects during the storm onset occurrences.  The storm onset was chosen around 0000 hrs universal time (UT) which corresponds with local time (LT) of American sector between (4-8 p.m.).  The result obtained shows geomagnetic storms with nighttime storm onset in all seasons are generally dominant to negative ionospheric storm while geomagnetic storm with daytime storm onset in all seasons to positive storm.