A pseudo three-dimensional resonance line radiative transfer model with overlapping lines

A description of a resonance line Feautrier radiative transfer (RT) code wh ich allows for coupling between closely spaced emission lines is presented. This code has been used to model closely spaced H and D Lyman alpha 1215.6 7 Angstrom and 1215.34 Angstrom emission lines, respectively, in the Jovian thermosphere. There is no direct interaction between these lines, but coup ling and energy transfer may occur as the Voigt broadened lines overlap. Th e RT method is pseudo three-dimensional in that a spherical shell atmospher e is accounted for in direct solar beam scattering but with one-dimensional (1-D) plane-parallel multiple scattering. In addition, allowance is made f or a varying solar zenith angle along the line of sight in calculating inte nsities. Using a model atmosphere for thermospheric D and H produced by a 1 -D photochemical- diffusion model, we present results illustrating the rela tive importance of including coupling of H and D Lyman alpha emission lines in radiative transfer calculations for both the disk and limb of Jupiter. These results suggest that the spectral contrast between the H and D Lyman alpha features is reduced in long limb path geometries and that the disk me asurement provides better detection possibilities.