P-LBLRTM Description


P-LBLRTM (Planetary LBLRTM) is a extension of LBLRTM_v12.1 with capabilities to model Martian and early Earth atmospheres. Since these atmospheres are not dominated by N2 and O2, but rather have high CO2 concentrations, accurate modeling of the effects of CO2 on the optical depth estimates becomes important and needs to be included.

P-LBLRTM has all the capabilities of LBLRTM, and uses the same TAPE5 input file. However, the spectroscopic input file requires more information than the current TAPE3 used by LBLRTM, as discussed below.

Some important P-LBLRTM features are as follows:

  • separate modules for Earth and Martian planetary properties, such as the acceleration of gravity and the mean molecular mass of the air;
  • separate species by species broadening parameters; currently the TAPE3 files provided only contain parameters for broadening of CO2 by H2O (Brown et al., 2007) and for the temperature dependence of broadening of CO2 by CO2 (Lamouroux et al., 2012), but the TAPE3 files and code have been structured to handle broadening of the first seven HITRAN species by any of these same species;
  • CO2 self line coupling has been included;
  • the foreign water vapor continuum has been increased to reflect the increased widths of CO2 broadened water vapor lines (relative to air) and the increased efficiency of collisions with CO2 based derived from the CO2 collision-induced absorption (CIA); for the latter we have followed the induced dipole moment approach of Gruszka and Borysow (1997) between 0 and 250 cm-1, and included the absorption due to dimers between 1200 and 1500 cm-1 of Baranov et al. (2004).
  • IMPORTANT! Most P-LBLRTM features have been incorporated into LBLRTM; only the changes made to the continuum for high CO2 levels have not been included. Furthermore, LBLRTM has been significantly upgraded since the release of LBLRTM_v12.1. We therefore highly recommend that users download LBLRTM instead of P-LBLRTM.

    Atmospheric and Environmental Research