SABER temperature observations in the summer polar mesosphere and lower thermosphere: Importance of accounting for the CO₂ν₂ quanta V–V exchange

The polar summer thermal structure, with its cold mesopause and steep temperature gradients, both below and above the mesopause, produces the largest non‐LTE effects in the CO 2 ν 2 mode manifold states. In this paper we focus on validating the non‐LTE model applied for operational temperature retrievals from the SABER 15 μ m limb radiance observations for these extreme conditions. We demonstrate that accounting for the redistribution of ν 2 quanta among various CO 2 isotopes shifts the retrieved summer 2002 polar mesopause altitude upwards by 2 to 4 km. It brings the SABER temperature measurements into a better agreement with those of falling sphere experiments, lidar observations, as well as with climatological data.