Examples of using E-CHAIM model

Readme.md

E-CHAIM altitude profile example

E-CHAIM ionospheric model is available for C, IDL, and Matlab. We will describe the Matlab version only here. There is a bug in E-CHAIM 4.3.0 and 4.3.1, and E-CHAIM 4.3.2 Matlab .zip is corrupted. I have emailed E-CHAIM team to let them know.

Until the E-CHAIM 4.3.2 download is fixed, use E-CHAIM Matlab release 4.2.1. Free registration is required to download the E-CHAIM Zip archive. Extract this archive from Matlab:

unzip('Release_Matlab_CDB-4.2.1.zip')

cd('Release_Matlab_CDB-4.2.1/')

The “ECHAIM.p” file is a function ECHAIM() accessed from Matlab. Unlike the “.m” script files one is used to, “.p” files are encrypted to keep source code private, but can be run just like “.m” files.

Let’s run a Matlab E-CHAIM self-test that will automatically compile the MEX code. If you get an error message about compilers not being setup, there should be a link in the Matlab error on how to setup the MEX compilers. From Matlab:

ECHAIM(‘test’)

If you get error

Unrecognized function or variable 'matlab_nrlmsise'

ECHAIM('create_nrlmsise')

Then, generate an electron density altitude profile by running this example script "altitude_profile.m"

altitude_profile.jpg

altitude_profile.m

dates_use = datetime(2013, 1, 23, 11, 24, 50);
lat_use = 55;
lon_use = 69.5;
alts_use = 60:1:1000;
Y = ECHAIM (lat_use, lon_use, dates_use, alts_use);

plot(Y.dens, Y.Alt)
set(gca, XScale='log', Xlim=[1e9,1e12])
title(sprintf("%s [%0.2f %0.2f]", string(t), lat_use, lon_use))
ylabel('Altitude [km]')
xlabel('Electron Number Density [e^- / m^3]')