Long-duration positive ionospheric storm during the December 2006 geomagnetic storm: Ionizing effect of forbidden electrons

The magnetosphere-ionosphere coupling at low latitudes was studied during the major geomagnetic storm on 14-16 December 2006. Data from NOAA/POES satellites were used to identify the enhancements of forbidden energetic electrons (FEE). Global Ionospheric Maps and COSMIC/FORMOSAT-3 radio occultation measurements were used for studying positive ionospheric storm phases. We found that long-lasting positive ionospheric storms were concomitant with FEE enhancements. We discussed relative contributions of the FEE ionizing effect as well as other general mechanisms to the positive ionospheric storm at different phases of the geomagnetic storm.