SAMM – Radiative Transfer Model

SAMM is an atmospheric background radiance and transmission code. It includes comprehensive coverage in the infrared, visible, and part of the ultraviolet spectrum (0.3 to 40 µm) for arbitrary lines-of-sight from the ground to 300 kilometers.

The SAMM code seamlessly combines the features of MODTRAN, a low altitude (30 km) non-LTE model. It includes all of the important absorption and emission bands of H2O, CO2, O3, N2O, CO, CH4, O2, SO2, NO2, NH3, HNO3, OH, N, O, NO+, N2, O+, N+ within that range. SAMM contains multiple radiative transfer algorithms to compute non-LTE radiance at a spectral resolution as fine as 0.001 cm-1. Its chemical kinetics model computes vibrational excitations of atmospheric profiles automatically generated by the Standardized Atmospheric Generator (SAG).

These features allow for the modeling of radiance along the solar terminator, taking into account both the change in atmospheric constituents and molecular excitations along the transition from day time to night time conditions. SAMM can further include complex upper-atmospheric processes along a line-of-sight, including spatially-dependent auroras, polar mesospheric clouds, and stratospheric warming events.

Comparison of temporal variations in auroral radiance at 8 µm as a function of tangent height between observations (top) and SAMM v3 calculations (bottom).