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Selecting band boundaries: Band boundaries are always chosen manually, but what are the restrictions on band width, e.g. to minimize the number of major gases in each band, or the variation in the Planck function?
Line-by-line model: Which LBL model is used?
Reordering spectrum: Is reordering done separately at each pressure level, or is there a unique mapping from wavenumber to g space?
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Selecting band boundaries: There are no restrictions on the width of a band, and indeed ecCKD can be used to generate full-spectrum correlated-k (FSCK) models.
Line-by-line model: LBLRTM version 12.8; in fact we use only the LBL calculations available from the CKDMIP FTP site.
Reordering spectrum: The spectra for the "median" CKDMIP present-day profile are reordered. Reordering is performed for "major" gases, which are configurable but for the "climate" application are H2O, O3, CO2, CH4, N2O, and in the shortwave only, a composite gas of O2+N2. For the "NWP" application the major gases are H2O, O3 and a composite gas containing all well-mixed gases at present-day concentrations. Each major gas is reordered separately (where a composite gas is treated as a single gas). A unique ordering is produced for each gas that is constant with pressure, i.e. we don't reorder separately at each pressure level. In the longwave, ordering is in terms of the height of the peak cooling rate for an idealized temperature profile that monotonically decreases with height. In the shortwave, ordering is in terms of the height at which the zenith optical depth to top-of-atmosphere is 0.25.
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