US-Nigeria Cooperative Research: Improvements of the International Reference Ionosphere at Low Latitudes

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0002144BilitzaThis award supports a three-year collaborative research project among Dr. Dieter Bilitza, with the Raytheon Technical Services Company at Goddard Space Flight Center in Greenbelt, MD; Professor Jacob Olusegun Adeniyi, of the Department of Physics at the University of Ilorin in Nigeria; and Professor Olivier Obrou, at the Laboratoire de Physique de l'Atmosphere at the University of Cocody in the Ivory Coast. The ionosphere is that part of the atmosphere which lies between the mesophere and the exosphere. Its layers are ionized by solar ultraviolet radiation, which facilitates the transmission of certain radio waves over long distances on earth. A good knowledge of ionospheric electron density is essential for any ground or space remote sensing technique that uses the ionospheric radio waves for the transmission of its signals. The most widely used model for determining these densities, the International Reference Ionosphere (IRI), lacks a description of the low latitude regions where the largest electron densities occur, which limits its ability to provide the corrections needed by navigation and communications systems. The three investigators will analyze equatorial observations of the bottom-side ionospheric electron density profiles collected by four ground-based sounders located near the magnetic equator in Burkina Faso, Nigeria, and the Ivory Coast. The results will be used to improve the specification of electron density in the IRI model. This information complements existing measurements in the American, Indian, and Pacific sectors, and completes the collection of electron density data from the longitudinal chain of ground-based sounders near the magnetic equator. These data sets will also enable the researchers to develop a quantitative description of the variability of the equatorial ionosphere in the African sector. This project combines the manual ionogram scaling done at the four stations with modern ionogram reduction techniques. Through this project the principal investigators expect to achieve a better understanding of the processes that shape the equatorial ionosphere, which will lead to improvements in the IRI standard model. An updated IRI model, which includes African measurements, will benefit future researchers, and it will also have broad application in high frequency and ground-to-satellite communications systems. Additionally, the anticipated results should expand the knowledge about ionospheric physics.The Division of International Programs and the Division of Atmospheric Sciences are jointly providing funding for this project.