September 29, 2017, 1:00 pm - 2:00 pm
September 29, 1:00 pm - 2:00 pm
Artificial and Natural Disturbances in the Equatorial Ionosphere: Results from the MOSC Experiment and the C/NOFS satellite mission
Dev Joshi (PhD candidate, Boston College)
The low-latitude ionosphere is characterized by large-scale instabilities in the post-sunset hours due to the distinct geometry of the earth's magnetic field lines at the equator. The magnetic field lines are horizontal at the equator contributing to the high vertical drift velocity of the plasma bubbles growing from the bottomside of the ionospheric F-region. The phenomenon, commonly known as equatorial spread F, is an important problem in aeronomy as it can cause radio wave scintillation effects representing the most critical impacts of space weather on man-made technologies, such as satellite communications and global navigation satellite systems (GNSS). Here, we present results from an artificial ionospheric modification experiment as well as from naturally occurring instabilities in the equatorial ionosphere. An artificial plasma cloud was created in the bottomside of the ionospheric F-layer during the so-called Metal Oxide Space Cloud (MOSC) experiment in May 2013 to study the interactions of artificial ionization with the background plasma under the hypothesis that the artificial plasma might suppress the occurrence of natural instabilities. While the suppression hypothesis remains open to debate, the propagation results confirm that the injection of artificial ionization in the lower F-region causes dramatic changes to the ambient HF propagation environment. With regard to natural processes, data from the AFRL/NASA C/NOFS satellite mission has been analyzed to investigate the characteristics of plasma bubbles from in situ observations in the context of ground based scintillation measurements. The investigation presented here will identify the regions affected by low-latitude scintillation and provide insight into the growth mechanism and longitudinal variability of equatorial spread F. We present a comparison between ground station scintillation observations and satellite observations of the ion density irregularities. This allows us to gain new insight into the meridional growth mechanism of equatorial plasma bubbles and the factors that determine the spatial evolution of spread F structures.