pymodtran – Thermal TUD Wrapper for MODTRAN 5

pymodtran is a small Python library that automates the generation of atmospheric thermal components using MODTRAN 5. It produces the three key outputs used in thermal remote sensing:

• Transmittance T(λ)
• Upwelling radiance U(λ)
• Downwelling radiance D(λ)

The user only provides:

• Surface temperature (Tsurf)
• Water vapor scale (h2o_scale)
• Ozone scale (o3_scale)

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📦 Installation

1. Create any folder on your computer (e.g. test_modtran/):
2. Inside that folder, install the library directly from GitHub:

pip install git+https://github.com/Jeferson0809/modtranpy.git

3. In the same folder, create a Python file (for example test_tud.py):

from modtran_tud import (
    run_TUD, set_modtran_dir,
    save_tud_npz, load_tud_npz,
    plot_TUD)

# Point to your local MODTRAN 5 installation
set_modtran_dir(r"C:\PcModWin5\Bin")


# Run a simulation
res = run_TUD(
    Tsurf=300.0,
    h2o_scale=1.0,
    o3_scale=1.0,
    h1=6.0,
    h2=0.0015,
    sensor_center=0.0,
    sensor_width=10.0 #cm-1
)

# Save the result as .npz
save_tud_npz(res, "T300_H1p0_O1p0.npz")

# Load the saved result (can be on another machine or in Colab)
res2 = load_tud_npz("T300_H1p0_O1p0.npz")

# Plot the T, U, D curves from the loaded file
plot_TUD(res2)

4. Run the script

python test_tud.py

⚙️ Requirements

● A local licensed installation of MODTRAN 5

● The directory passed to set_modtran_dir() must contain the MODTRAN executable

Example: C:\PcModWin5\Bin\