Review of Long-Term Trends in the Equatorial Ionosphere Due the Geomagnetic Field Secular Variations and Its Relevance to Space Weather
Ana G. Elias,
Blas F. de Haro Barbas,
Bruno S. Zossi,
Franco D. Medina,
Mariano Fagre,
Jose V. Venchiarutti
Affiliations
Ana G. Elias
Laboratorio de Ionosfera, Atmosfera Neutra y Magnetosfera (LIANM), Departamento de Física, Facultad de Ciencias Exactas y Tecnologia (FACET), Universidad Nacional de Tucuman (UNT), Tucuman 4000, Argentina
Blas F. de Haro Barbas
Laboratorio de Ionosfera, Atmosfera Neutra y Magnetosfera (LIANM), Departamento de Física, Facultad de Ciencias Exactas y Tecnologia (FACET), Universidad Nacional de Tucuman (UNT), Tucuman 4000, Argentina
Bruno S. Zossi
Laboratorio de Ionosfera, Atmosfera Neutra y Magnetosfera (LIANM), Departamento de Física, Facultad de Ciencias Exactas y Tecnologia (FACET), Universidad Nacional de Tucuman (UNT), Tucuman 4000, Argentina
Franco D. Medina
Laboratorio de Ionosfera, Atmosfera Neutra y Magnetosfera (LIANM), Departamento de Física, Facultad de Ciencias Exactas y Tecnologia (FACET), Universidad Nacional de Tucuman (UNT), Tucuman 4000, Argentina
Mariano Fagre
Laboratorio de Telecomunicaciones (LTC), Departamento de Electricidad, Electrónica y Computación, Facultad de Ciencias Exactas y Tecnología (FACET), Universidad Nacional de Tucumán (UNT), Tucuman 4000, Argentina
Jose V. Venchiarutti
Laboratorio de Ionosfera, Atmosfera Neutra y Magnetosfera (LIANM), Departamento de Física, Facultad de Ciencias Exactas y Tecnologia (FACET), Universidad Nacional de Tucuman (UNT), Tucuman 4000, Argentina
The Earth’s ionosphere presents long-term trends that have been of interest since a pioneering study in 1989 suggesting that greenhouse gases increasing due to anthropogenic activity will produce not only a troposphere global warming, but a cooling in the upper atmosphere as well. Since then, long-term changes in the upper atmosphere, and particularly in the ionosphere, have become a significant topic in global change studies with many results already published. There are also other ionospheric long-term change forcings of natural origin, such as the Earth’s magnetic field secular variation with very special characteristics at equatorial and low latitudes. The ionosphere, as a part of the space weather environment, plays a crucial role to the point that it could certainly be said that space weather cannot be understood without reference to it. In this work, theoretical and experimental results on equatorial and low-latitude ionospheric trends linked to the geomagnetic field secular variation are reviewed and analyzed. Controversies and gaps in existing knowledge are identified together with important areas for future study. These trends, although weak when compared to other ionospheric variations, are steady and may become significant in the future and important even now for long-term space weather forecasts.