TY - JOUR
TI - Absorption coefficient of CO2 and first-order approximation of radiative forcing
AU - Ostrogorsky Aleksandar G
JN - Thermal Science
PY - 2025
VL - 29
IS - 1
SP - 731
EP - 749
PT - Article
AB - The CO2 is one of the two primary GHG and the source of carbon needed for photosynthesis and life on Earth. The spectral absorption coefficient α(λ) [m–1] is a fundamental property of CO2. It is required for modelling heat transfer at high temperature in furnaces, heat engines, wild fire, etc. and in the atmosphere at ~300 K. Using a FTIR spectrometer, infrared absorbance A(λ) spectra of CO2 were measured with 0.5 cm–1 resolution. All measurements were conducted at 295 K. The spectra cover the wavelength range 2 μm < λ < 18.2 μm and the pressure range 0.04 atm < p < 3 atm. The spectra were used to determine the spectral absorption coefficient α(λ) in the bands adjacent to the peaks 2.7 μm, 4.26 μm, and 15 μm. The spectra of CO2 in air are also presented. A first-order approximation-model of the radiative forcing, Δq, is presented. The FTIR spectra confirm that 400 ppm of CO2 is sufficient to saturate absorption in the central PQR region of the 15 μm band. Consequently, radiative forcing is controlled by the wings (edge) regions of the 15 μm band. The 100% increase in CO2 concentration will cause radiative forcing, Δq400ppm to 800ppm = 2.79 W/m2, and temperature increase ΔT ~ 0.7 K. Tenfold (1000%) increase in CO2 concentration will increase radiative forcing by ~ 1.8x, so that Δq400ppm to 4000ppm = 5.03 W/m2 and ΔT ~ 1.2 K.