Global Atmospheric Density Estimation

ODTK provides the capability to simulate or estimate corrections to selected parameters within the a priori global atmospheric density model. This feature is currently supported for the Jacchia 1970 and Jacchia-Bowman 2008 atmospheric density models. In addition, plug-in density models can advertise parameters which can be estimated.

Global Atmospheric Density Estimation
Parameter Description
Mode When the Nominal mode is selected, the atmospheric density is computed as prescribed by the a priori model without modification. Select Estimate to generate deviated density values (simulator) or estimate corrections to the selected density model parameters. Simulated density values are generated via random deviations of the selected density model parameters in accordance with their stochastic definition. Select Correct to allow specification of density model parameters via a file.
Model
(Estimate)		 Select the a priori atmospheric density model for which parameter corrections are desired. Currently limited to the Jacchia 1970 and the Jacchia-Bowman 2008 atmospheric density models and plug in density models which have advertised parameters for estimation.
Parameterization
(Estimate) 		Select the parameters which you desire to simulate or estimate. When using the built-in Jacchia 1970 or Jacchia-Bowman 2008 models the following estimation options are available:
  1. Select Tc_Tx to use a parameterization that mirrors that used in the Dynamic Calibration of the Atmosphere (DCA) performed by the USAF. Under the selection, corrections are made to the nighttime minimum exospheric temperature, Tc, and the inflection point temperature at 125 km altitude, Tx.
  2. Select Tinf to simulate or correct the global exosphere temperature, Tinf.
  3. Select DeltaRhoOverRho to model corrections as a ratio of the computed a priori density.

When using a plug-in atmospheric density model the following estimation options are available:

  1. The plug-in model can advertise a parameterization which may be selected.
  2. Select DeltaRhoOverRho to model corrections as a ratio of the computed a priori density.
EstimationParameters (Estimate) Provides a list of stochastic parameters which may be modeled as either scalars (corrections have no positional dependence) or as low degree and order spherical harmonic expansions. The spherical harmonic expansions are defined in a reference frame with the Z axis aligned with the Earth Fixed Z axis and the X axis pointed in the direction of the Sun. Note that the same reference frame definition is used regardless of which parameterization is selected.
CorrectionFilename (Correct) Name of the file containing corrections to atmospheric density model parameters. You can use a Global Density Correction file (*.gdc).
LimitCorrectionEpoch (Correct) Set an artificial limit on the final epoch in the provided data file.
LastestCorrectionEpoch (Correct) Artificial limit on the final epoch in the provided data file. When density model parameter corrections are requested at epochs later than this time, the correction values at the LatestCorrectionEpoch are returned.