Calculations of the limb radiance of Venus and Mars in IR CO2 bands with allowance for non-LTE

Theoretical estimates of limb total band radiance in the vibration-rotation CO₂ bands are presented for the first time for both Venus' and Mars' atmospheric layers with nonequilibrium population of vibrational CO₂ states. The daytime vertical profiles of limb radiance have been obtained in the 1.2; 1.4; 1.6; 2.0; 2.7 and 4.3 μm bands, and the nighttime ones - in the 4.3 μm band only. The daytime profiles have a radiance maximum caused by the increase of the vibrational states population with altitude, which is due to sunshine absorption in the infrared CO₂ bands. The nighttime profiles reveal an abrupt decrease in the radiance lapse rate with altitude, which is caused by the population maximum of vibrational states due to tropospheric thermal radiation absorption in the 4.3 μm band.