MSIS Density Models

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The MSIS-00, MSIS-90, and MSIS-86 atmospheric models use a combination of F10.7 flux and Ap data to determine atmospheric density as a function of geopotential height. For more information on the MSIS models courtesy of the Naval Research Laboratory, see this website: NRL Mass Spectrometer, Incoherent Scatter Radar Extended Model.

 

This page is divided into the following sections:

Enabling MSIS Drag Modeling

Setting the Solar Flux Predictor File

 

 

Enabling MSIS Drag Modeling


The default atmospheric density model used for modeling the Earth's atmosphere is the Analytic Density Model. To enable an MSIS Density Model for a Spacecraft, edit the Spacecraft, proceed to the Force Model page, and select Earth from the list of celestial bodies as shown in the image below.

 

Then ensure that "MSIS-2000", "MSIS-90", or "MSIS-86" is selected in the Density Model drop-down menu.

 

 

To enable MSIS atmospheric density modeling via FreeFlyer script, use the following syntax:

 

Alias fm = (Spacecraft1.Propagator AsType RK89).ForceModel; // This alias is used to shorten the script examples below

 

fm.DragType = 4;

 

Where the DragType can be one of the following:

1 for Analytic density

2 for Harris-Priester density model

3 for Jacchia-Roberts density model

4 for MSIS-2000

5 for MSIS-90

6 for MSIS-86

 

 

Setting the Solar Flux Predictor File


By default, FreeFlyer uses the "Jacchia.dat" data file for atmospheric modeling, but this file will NOT work with the MSIS models. You must specify a different file using the "Solar Flux Predictor File" file browser shown in the image above or via FreeFlyer script using this syntax:

 

fm.DragDataFile = "F10_7_Ap_Ascii.dat";

 

Where "F10_7_Ap_Ascii.dat" specifies the path and filename of the predictor file. There are two predictor files included with FreeFlyer, F10_7_Ap_Ascii.dat and F10_7_Ap_Ascii_long.dat. For more information about these files, see the MSIS Model Files reference.

 

 

See Also


ForceModel Properties and Methods

Solar System settings that affect Spacecraft Propagation