New spectroscopic database of CO2 in the 1.6 and 2.0 µm spectral regions for remote sensing

Abstract

New FTS measurements of pure, air-, and H2O-broadened CO2 in the air pressure range 100-1000 mbar and the temperature range 200-296 K for the 1.6 and 2 µm bands were carried out in the frame of the ESA-funded ISOGG (Improved Spectroscopy for satellite measurements Of Greenhouse Gases) project for the upcoming CO2M mission. The analysis of pure CO2 in the 1.6 µm band showed intensity depletion in the line cores with increasing pressure and corresponding intensity redistribution to a continuum that varies quadratically with pressure. Accurate line intensities with sub-permille uncertainty were determined, as well as air- and H2O-broadened line profile parameters including speed-dependence and first order Rosenkranz line mixing. The temperature dependence of the air-broadening line profile parameters was also obtained. The temperature dependence of air intensity depletion and the continuum were calculated from second order virial coefficients based on the pure CO2 results, and line parameters among different bands were compared with HITRAN20. Absorption cross sections were calculated on the ABSCO 5.2 wavenumber, pressure, temperature, and H2O VMR grids and compared with ABSCO 5.2 by retrieval simulations of TCCON measurements. Continuum and line core intensity depletions were found to be relevant for atmospheric observations.