The Successive Orders of Scattering (SOS) approach [1] is one of the well known methods for solving the Radiative Transfer (RT) problem. Its efficiency in terms of speed and accuracy of computation was already demonstrated for scattering and absorbing atmospheres in Solar spectrum. Although there are no principle limitations to account for the emission processes, the application of the SOS method for atmospheres with thermal emission is not widely used yet. In this paper we present a SOS-based RT approach accounting for the full source function, which enables its application from the UV (UltraViolet) to the TIR (Thermal InfraRed) parts of the electromagnetic spectrum. The atmospheric vertical discretization in this extended SOS scheme is a key point in order to properly retain the scattering and emission processes. An analysis of different methodologies to perform this vertical discretization is presented. The numerical implementation has been included in GRASP (Generalized retrieval of Atmosphere and Surface Properties) RT code [2]. In comparison with the widely used code DISORT (DIScrete-ORdinatemethod for Radiative Transfer) [3], the developed SOS scheme achieves a mean accuracy of radiance calculation of $-$0.005 K ($-$0.003%) expressed in terms of brightness temperature. Under the same configuration and vertically inhomogeneous atmospheric conditions, GRASP SOS RT is approximately eight times faster than DISORT. The analysis of the sensitivity of GRASP TIR SOS scheme to the number of layers and the effect of polarization are also investigated in the paper.

连续散射顺序 (SOS) 方法 [1] 是解决辐射传输 (RT) 问题的众所周知的方法之一。它在计算速度和准确性方面的效率已经在太阳光谱中的散射和吸收大气中得到证明。尽管对排放过程没有原则上的限制，但 SOS 方法在热排放大气中的应用尚未得到广泛应用。在本文中，我们提出了一种基于 SOS 的 RT 方法，该方法考虑了完整的源函数，使其能够应用从电磁光谱的 UV（紫外线）到 TIR（热红外）部分。该扩展 SOS 方案中的大气垂直离散化是正确保留散射和发射过程的关键点。分析了执行这种垂直离散化的不同方法。数值实现已包含在 GRASP（大气和表面属性的广义检索）RT 代码 [2] 中。与广泛使用的代码 DISORT (DIScrete-ORdinatemethod for Radiative Transfer) [3] 相比，所开发的 SOS 方案实现了辐射计算的平均精度$-$0.005 K ($-$0.003%）以亮温表示。在相同的配置和垂直不均匀的大气条件下，GRASP SOS RT 比 DISORT 快大约八倍。文中还研究了GRASP TIR SOS方案对层数的敏感性和极化效应的分析。