International Reference Ionosphere (IRI) Model
ASTRA routinely uses the International Reference Ionosphere model, available for public use from http://modelweb.gsfc.nasa.gov/ionos/iri.html. IRI estimates the ionospheric electron density, electron temperature, ion temperature, and ion composition in the altitude range from about 50 km to 2000 km. ASTRA uses IRI as inputs to various models when a simple ionosphere is sufficient, such as IDA4D and Radio Raytracing . It is also readily used to estimate ionospheric conditions for radar deployments.