Estimation of electron densities in the lower thermosphere from GUVI 135.6 nm tomographic inversions in support of SpreadFEx

Abstract. The SpreadFEx campaign was conducted with the goal of investigating potential neutral atmospheric dynamics influences in seeding plasma instabilities and bubbles extending to higher altitudes from September to November 2005, with primary measurements in Brazil. In this paper, we present the results of space-based UV and ground-based optical observations in support of this campaign. Specifically, we present multi-dimensional electron density images obtained tomographically from the 135.6 nm emissions measured by the GUVI instrument aboard the TIMED satellite that result from radiative recombination of O⁺ and compare those with the corresponding 630.0 nm OI images recorded in the Brazilian sector. The GUVI results provide altitude vs. longitude information on depleted regions in the ionospheric plasma density that are complementary to the single-height latitude-longitude images obtained with the airglow imager.