In the early 2000s, the CHAMP satellite measured an atmospheric neutral mass density enhancement at around 400 km. This enhancement occurs in both northern and southern hemispheres at locations near the ionospheric “footprints” of Earth’s geomagnetic  cusps. 

Physical processes are possible to support this extra mass, but no signatures of these have been directly observed. Models indicate that there should be strong neutral wind perturbations, in the region of the density enhancement. I have used two ground-based Fabry-Perot Interferometers (FPI’s), located at McMurdo and the South Pole Stations, to  derive averaged wind speeds around 240 km from Doppler shifts of  the 630 nm oxygen emission. By comparing data from periods when the instruments were in the cusp region versus when they were not, I was able to look for any abnormal behavior. This analysis revealed that no wind signatures of a density enhancement were visible at 240 km, indicating that the physical process must be occurring at higher altitudes.