COSMIC/FORMOSAT-3 tomography of SEP ionization in the polar cap

We studied ionization effects produced by solar energetic particles (SEP) in the northern polar ionosphere and atmosphere during December 2006 (local night). Height profiles of specific ionization produced by the SEP in the polar cap were calculated using POES data on energetic particles. The SEP ionization dynamics reveals three intensifications at heights from 50 to 100 km in 7 to 8, 13 and 14 December. At the same time a 3-D tomography of electron content (EC) in the ionosphere and upper atmosphere was performed on the base of COSMIC/FORMOSAT-3 sounding data. We found pretty close temporal and spatial patterns for the EC enhancements and for the SEP ionization. The discrepancies might be attributed to three effects: unaccounted contribution of low-energy electrons to the ionization of lower ionosphere, fast growth of electron losses with the depth in atmosphere, and strong contribution from storm-time ionospheric disturbances.