ASTRA - Atmospheric & Space Technology Research Associates, LLC

Real-Time Modeling and Forecasting

ASTRA has developed a real-time modeling and forecasting system using AMIE and TIME-GCM.  The system calculates atmospheric properties from the mesosphere to the ionosphere in real-time and forecasts 30-60 minutes in the future.


ASTRA’s world class modeling capabilities include the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM). The model predicts global 3-D temperature, density, composition and wind fields for the neutral gas, as well as ionospheric electron density and ion distributions from 30 km to about 600 km altitude. The TIME-GCM is the latest in a series of GCMs, which were initially developed at the National Center for Atmospheric Research (NCAR) [Roble and Ridley, 1994]. Dr. Crowley led a team that ported the TIME-GCM code to a workstation environment, and parallelized it
[Crowley et al., 1999; Freitas and Crowley, 1999].
ASTRA strives to advance the TIME-GCM’s capabilities beyond traditional numerical experiments to the modeling of real “space weather” events in the thermosphere and ionosphere.


ASTRA’s world class modeling capabilities include the Martian middle and upper atmosphere.  ASPEN-Mars simulates the Martian atmosphere from about 14 km to the exobase, including the ionosphere. ASPEN-Mars currently solves for the neutral, electron and ion temperature profiles as well as for the compositional profiles of CO2, N2 and OX = (O + O3), coupled through major species diffusion equations. It also includes as minor species with transport and photochemistry: O2, Ar, N(4S), NOX = (NO + NO2),
H2O, H2, CH4, CO, and HOx = (H + OH + HO2) as well as ion chemistry.

International Reference Ionosphere Model

ASTRA routinely uses the International Reference Ionosphere model (Bilitza, 1990) which estimates the ionospheric electron density, electron temperature, ion temperature, and ion composition in the altitude range from about
50 km to 2000 km.

Mass Spectrometer and Incoherent Scatter Model

ASTRA routinely uses the NRLMSISE-00 empirical model of Hedin [1983, 1986, 1990] and Picone, et al. 2002. MSIS provides estimates of neutral temperature, exospheric temperature, densities of He, O, N2, O2, Ar, H, and N, and total density.  We are helping NRL develop the next generation of empirical wind models (HWM).

Radio Raytracing

ASTRA has a number of proprietary codes which permit radio waves of different frequencies, elevation and azimuth angles to be launched into realistic ionospheric electron density distributions to determine their propagation paths. This capability is useful for the study of radio propagation, radio system design, and data analysis.

Trajectory Analysis

ASTRA uses Trajectory Analysis to permit investigation of the evolution and source of ionospheric plasma and neutral density parcels.