Semi-empirical FAL models

The classical models by Fontenla, Avrett, Loeser (1993) provide one-dimensional, static, semi-empirical stratifications for different Quiet Sun and plage atmospheres. These models are useful as a reference and starting point. Their purpose is to describe the average stratification but they cannot - by nature - reproduce the dynamic and intermittent aspects of the solar atmosphere. 

Model properties

  • Target: quiet Sun, plage.

  • Grid points: 70 (models A,C,F) or 66 (model P)

  • Height range (z):  100km below optical depth unity (top of convection zone) to 1740km-2277km (depending on the model). Please note that the height axis is reversed with negative values in the atmosphere and positive values in the convection zone.

  • Grid resolution, vertical:variable.

  • Magnetic field: none

Available model data

Four different models for different regions are provided in the directory

ID type of region link points
A Quiet Sun, faint 70
C Quiet Sun, average 70
F Quiet Sun, bright 70
P Plage, typical 66


Quantity* Symbol Unit
Line number    
Depth Depth km
Gas temperature Temp. K
Electron density Electron 1/cm3
Proton density Proton 1/cm3
H population density of ground level H(1) 1/cm3

* Quantities ordered in the same way as in the data files (and tables in the original paper).

How to load the data in IDL: The data is tabulated in ASCII with a fixed format with 6 columns (see table above), which can easily read with the built-in routine READ_ASCII:


The variable data will contain a data structure and some unwanted lines due to the comment lines in the file. You can get rid off these by: 


for models A,C,F or


for model P.

Synthetic observables

  • To be added.

Simulated ALMA observations

  • None available yet.


Published Feb. 3, 2016 12:16 PM - Last modified Mar. 28, 2019 11:13 PM