Arts is a radiative transfer model. It is written in C++ and Python and is available as open source under the GNU General Public License (GPL) or the GNU Lesser General Public License (LGPL) via GitHub.

The model is able to simulate:

  • Passive and active microwave and sub-millimeter observations

  • Passive infrared observations

  • Passive visible and ultraviolet observations, including first order solar scattering

  • Observations from ground, airborne, and space-borne platforms

  • Observations of the Earth, other planets, and moon

  • Observations of the atmosphere, ocean, and land surface

  • Radiative flux and radiances in an atmosphere

The model supports:

  • Polarized radiative transfer

  • Spherical atmospheric geometry

  • Analytical Jacobians for many quantities

  • Retrieval of sensor parameters

  • Retrieval of surface parameters

  • Retrieval of atmospheric state parameters

  • Retrieval of line-by-line absorption parameters

  • Solving rotational non-lte level populations

  • Solving for the Zeeman effect in the presence of a magnetic field