An accelerated line-by-line option for MODTRAN combining on-the-fly generation of line center absorption within 0.1 cm-1 bins and pre-computed line tails

摘要: A Line-By-Line (LBL) option is being developed for MODTRAN6. The motivation this development two-fold. Firstly, when MODTRAN validated against an independent LBL model, it difficult to isolate the source of discrepancies. One must verify consistency between pressure, temperature and density profiles, column calculations, continuum particulate data, spectral convolution methods, more. Introducing a directly within will insure common elements all calculations other than those used compute molecular transmittances. second upgrade that enable users high resolution transmittances radiances full range current applications. In particular, introducing feature into first-principle scattered radiances, often not readily available with models. one 0.1 cm-1 bin at time, marching through requested band pass. algorithm use highly accurate, pressure- temperature-dependent Pade approximant fits contribution from line tails define absorption transitions centered more 0.05 each bin. beauty approach on-the-fly computations only require explicit summing 0.2 region. That is, distant lines be pre-computed via approximants. status effort presented. This include initial thermal solar radiance validation self-validations model its own calculations.