FASCOD uses a line-by-line model and takes into account all parameters characterizing the absorption lines (intensity, transition probability, etc.). It is based on the high-resolution molecular absorption database, HITRAN. The principal line parameters included in HITRAN are the resonance frequency, line intensity at 296 K, probability of a transition, half-width of the line at 296 K, and the low energy or fundamental molecular state. There are three linked models developed in the Air Force Geophysics Laboratory (AFGDL) with various spectral resolutions: LOWTRAN 7 Low Resolution Transmission Spectral resolution is 20 cm−1 (equivalent – – – to 600 GHz) in 5 cm−1 steps. MODTRAN 3 Moderate Resolution Transmission Spectral resolution is 2 cm−1 – – – (equivalent to 60 GHz) in 1 cm−1 steps. HITRAN 2004 High Resolution Transmission Spectral resolution is 0.001 cm−1 – – – (equivalent to 30 MHz). All of the models contain spectral information about many atmospheric species including H2O, O3, N2O, CO, CH4, O2, NO, NO2, SO2, and HNO3. (HITRAN includes details of over 1 000 000 absorption lines for 37 molecules.) In addition the three models include the H2O continuum across the entire spectrum, the N2 continuum in the 2 000 to 2 700 cm−1 region, molecular scattering, together with absorption and scattering from aerosol, fog, rain and clouds.
FASCOD uses a line-by-line model and takes into account all parameters characterizing the absorption lines (intensity, transition probability, etc.). It is based on the high-resolution molecular absorption database, HITRAN. The principal line parameters included in HITRAN are the resonance frequency, line intensity at 296 K, probability of a transition, half-width of the line at 296 K, and the low energy or fundamental molecular state. There are three linked models developed in the Air Force Geophysics Laboratory (AFGDL) with various spectral resolutions: – LOWTRAN 7 – Low Resolution Transmission – Spectral resolution is 20 cm−1 (equivalent to 600 GHz) in 5 cm−1 steps. – MODTRAN 3 – Moderate Resolution Transmission – Spectral resolution is 2 cm−1 (equivalent to 60 GHz) in 1 cm−1 steps. – HITRAN 2004 – High Resolution Transmission – Spectral resolution is 0.001 cm−1 (equivalent to 30 MHz). All of the models contain spectral information about many atmospheric species including H2O, O3, N2O, CO, CH4, O2, NO, NO2, SO2, and HNO3. (HITRAN includes details of over 1 000 000 absorption lines for 37 molecules.) In addition the three models include the H2O continuum across the entire spectrum, the N2 continuum in the 2 000 to 2 700 cm−1 region, molecular scattering, together with absorption and scattering from aerosol, fog, rain and clouds.
R-REC-P.1817-1-201202-I!!MSW-E.docx