Calculation of absorption and dispersion spectra of atmospheric gases at millimetre-wavelengths

Abstract

Absorption and dispersion spectra of the most important and millimetre-wave active atmospheric gases for arbitrary atmospheric paths are calculated. The atmospheric propagation model (APM) adopts a line by line summation technique to characterise the resultant resonant absorption and dispersion spectra of various trace constituents such as O3, N2O, CO, NO, NO2, SO2, ClO, HNO3, NH3 and major contributors H2O and O2. The model assumes a spherically layered atmosphere with each layer taken to be in local thermodynamic equilibrium and with exponential profiles of density and pressure between layer boundaries. The relative air mass integral and the line shape function are also appropriately evaluated.