摘要：Coincident and near-coincident Global Ultraviolet Imager (GUVI) and Special Sensor Ultraviolet Spectrographic Imager (SSUSI) plasma bubble images provide a unique opportunity to image the evolution of a single feature over a large longitude and time range. SSUSI and GUVI are currently the only two UV imagers that can provide low-Earth orbit measurements capable of reconstructing a multidimensional electron density map. New imaging techniques applied to years of UV data provide a powerful tool for observing and understanding ionospheric electron density and equatorial plasma bubbles. GUVI, launched on board the TIMED satellite in December 2001, and SSUSI on board the DMSP F16 satellite launched in October 2003 have several overlapping years of observations of the nightside ionosphere. The low-Earth orbit of the DMSP and TIMED satellites allows for tomographic reconstruction of altitude versus longitude bubble cross sections from UV disk images. GUVI is at an altitude of 625 km in an orbit that precesses through all local solar times in just 60 days, and SSUSI is at an altitude of 830 km in a fixed 0800/2000 local solar time orbit. We have developed a technique for tomographic retrievals of electron density maps from GUVI observations. We are able to produce three-dimensional maps of ionospheric electron density. We discuss the adaptation of the tomographic imaging technique to SSUSI data and present initial results. Electron density reconstructions are accompanied by discussion and analysis of plasma bubble drift rates and the morphology and time changes in the tilt of the bubbles as they drift through the ionosphere.
