Understanding the Unique Equatorial Density Irregularities

: The Earth's ionosphere is the well-known threat for applications that depend on trans-ionospheric radio waves. For example, it affects applications like navigation, positioning, and terrestrial communication. The behavior of the ionosphere has been investigated for the past two-three decades all over the globe. However, there are regions, like Africa, that have not been investigated until recently due to lack of ground-based ionospheric monitoring devices. LEO satellite observations in the African sector show unique equatorial ionospheric structure. For example, this region equatorial plasma bubbles, which produce scintillation of radio waves, are much deeper and occur more frequently than bubbles observed in the other region. WaGRL houses different ionospheric monitoring instruments such as SCINDA GPS receiver, Galileo receiver, LEO satellite signal receivers and others in collaboration with institutions outside Ethiopia. This effort provided some support for the installation of the HF Coherent Backscatter Radar (Blue Nile Radar) at Bahir Dar University in collaboration with AFRL in November 2014. Ionospheric empirical models such as NeQuick and IRI have been developed using data collected from ionosondes installed unevenly on the Earth (primarily mid-latitude Northern hemisphere). For realistic ionospheric characteristics estimation for the African ionosphere these models are now using measurements collected locally. The methods developed in this work are also useful for computing three dimensional electron density profiles. Similarly, ionospheric tomography has been applied to reconstruct the ionospheric electron density from GPS receiver measurements. The MATLAB code developed to implement this method is also one of the outputs of this project. These efforts have resulted in six published or submitted publications.