The variable MODEL selects among one of the six geographical-seasonal model atmospheres, a gas-free atmosphere or specified atmosphere model from radiosonde data, thus defining the vertical structure of the atmosphere in terms of pressure, temperature and gas concentration (specifically H2O and O3). The available options are shown in the Table below:
Value(s) | Description |
---|---|
1 |
Tropical *
|
2 |
Mid-Latitude Summer * Default value
|
3 |
Mid-Latitude Winter *
|
4 |
Sub-Arctic Summer *
|
5 |
Sub-Arctic Winter *
|
6 |
1976 US Standard *
|
0 |
No Gas Absorption
|
<0 |
User-input model(s)
See here for further information. |
* Same model atmospheres from (McClatchey et al., 1972) as implemented in 6SV code.
Altitude vs temperature profiles for the default MODTRAN atmospheric models. Source: MODTRAN site
Altitude vs H2O and O3 concentration (left and right respectively) profiles for the default MODTRAN atmospheric models. Source: MODTRAN site
This variable, therefore, has an impact on the simulation of the absorption-scattering processes at various altitudes in the sun-target-sensor optical path.
The predefined columnar content of CO2, O3 and H2O in each model can be overwritten respectively by the key input variables CO2MX, O3STR and H2OSTR.
McClatchey, R.A., Fenn, R.W., Shelby, J.E.A., Volz, F.E., & Garing, J.S., (1972), "Optical properties of the atmosphere." 3rd Ed., Tech. Rep. AFCRL72-0497, 108 pp. Air Force Geophysics Laboratory, Hanscom AFB, Mass.