Space Weather Systems
Real-Time Ionospheric Characterization
We have developed a versatile, user-friendly software system for describing the ionosphere’s 3-D and 4-D distributions in the ionosphere. The system can accept ionospheric data from diverse sources and geographic locations. The data may be fed in real-time or processed offline. The software system completely specifies the ionosphere over any region of the world. It starts with a user-specified ionospheric model as initial guess and assimilates various data sets self-consistently. The system is available for collaborative research and for other specific applications
The software divides into two programs. The first is a simulation program that generates a model ionosphere and calculates TEC values based on user-defined receiver arrays and satellite constellations. The second program uses TEC output from the first to reconstruct the ionosphere in four dimensions. Each allows native visualization of electron density in contour, three-dimensional, and false color plots, as well as contours of peak density and peak height. The software can display TEC values versus time for all receivers and satellites, and includes a 3-D interactive plot of the geometry.
Ongoing work includes the adaptation of the current 4-D ionospheric tomography software for the purpose of simulating and investigating the effect of satellite-based receivers on the tomography problem. The software includes the ability to place any number of both ground- and satellite-based receivers using any possible orbit to simulate various arrangements. Satellite-based receivers may have their own beacons, increasing the total amount of TEC data. In addition, users may load the actual GPS constellation, or any other satellite or satellites, into the software.
A number of methods can simulate the ionosphere, including the Air Force PIM model, IRI and a simple slab, and Chapman. Users can adjust the base ionosphere, including height and density gradients, as well as localized bulges. The models can represent any location of the world with variable resolution in height, latitude, and longitude. The reconstruction software will use these simulated TEC values in its reconstruction. The software includes many standard tomography algorithms as well as some proprietary algorithms developed by CRS. In addition, support for input other than TEC is available to improve overall reconstruction. Other models could easily work with the software as well.
After the software modifications are complete, tests will investigate the improvements to reconstruction that satellite-based GPS receivers offer.