H2O Broadening of a CO2 Line and Its Nearest Neighbors Near 6360 cm–1

Remote sensing of CO2 requires high-fidelity reference data of spectral line parameters to be successful. The 6360 cm–1 region is commonly used by satellites, field campaigns, and point-source gas sensors because it contains well-characterized and relatively isolated transitions of appropriate line strengths for atmospheric applications. However, the presence of gases other than CO2, N2, and O2 can be a source of uncertainty for atmospheric measurements. Near 6360 cm–1, there are numerous H2O and HDO transitions. Water makes up approximately 1–4% of Earth’s lower atmosphere and can interfere with remote sensing measurements by (1) appearing as a direct spectral interference or (2) acting as a foreign broadener for CO2 lines. The primary goal of this work was to quantify H2O broadening of CO2 through precision spectroscopy measurements on the R16e transition at 6359.967 cm–1 and its two nearest neighbors. A secondary goal was to assess the accuracy of H2O reference line parameters in the HITRAN 2008 database for spectrally removing typical levels of moisture from air samples containing approximately 400 ppm of CO2.