Modeling Short- and Long-term Variability in the Ionospheric D and E regions
Abstract
The ionosphere extends from about 50 km to over 500 km above the Earth’s surface, and is characterised by elevated levels of positive ions, negative ions and electrons. These ionized species are produced mainly by solar radiation in the extreme ultra-violet, but also by energetic charged particles (protons and electrons) from the sun as well as galactic cosmic rays from outside the solar system. This project will focus on variability in the ionosphere on time-scales from minutes to decades, with a particular focus on Sporadic E layers. These are thin layers of metallic ions (Fe+, Mg+ etc.) which occur at heights between 90 and 140 km. The source of the metals is the ablation of the roughly 40 tonnes of cosmic dust particles which enter the atmosphere every day. Sporadic E layers have a significant impact on radio communications: they facilitate over-the-horizon communications by forward-reflecting radio waves back to the ground, but also prevent space-to-ground communications unless the radio frequency is high enough to penetrate through the layers. Being able to predict the time and height occurrence of these layers, and also their peak electron concentration – which determines the frequency threshold for radio transmission – is clearly important. Moreover, climate change is driving profound long-term variations in the temperature, winds and densities of the ionosphere, which are likely to cause substantial changes to sporadic-E behaviour over the 21st Century.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 21, 2022
- Source ID
- FA86552117031XX0
Entities
People
- John M. C. Plane
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Leeds