Moliere (v5): a versatile forward- and inversion model for the millimeter and sub-millimeter wavelength range

Recent advancements in the development of passive millimeter and sub-millimeter wave heterodyne techniques for ground-based, air-borne, and space-borne observations of key parameters in Earth's middle atmosphere have triggered the development of adequate data analysis methods and models. This paper provides a detailed description of the versatile forward- and inversion-model for the millimeter- and sub-millimeter wavelength range, MOLIERE (v5) (Microwave Observation LIne Estimation and REtrieval, version 5). Present applications of the model include data analysis for ground-based and space-borne heterodyne instruments such as the sub-millimeter radiometer (SMR) on board the Odin satellite as well as definition studies for future limb sensors dedicated to Earth observation and Mars exploration. The physical and mathematical basics of the forward- and retrieval-model parts are presented. The main emphasis is then put on the description of the numerical implementation of the algorithms for radiative transfer and weighting function computations as well as on the employed method for modeling atmospheric refraction.