Dr. Alexander Kutepov (The Catholic University of America and NASA GSFC) and Dr. Konsatantinos Kalogerakis (SRI International) will deliver a talk on the topic "New Look at the Atomic Oxygen in the nighttime Mesosphere and Lower Thermosphere" in the IAP Colloquium in this winter semester 2021-22, on Thursday, 1st Dec 2021.

The scientific talk is based on their collaborative research work regarding the atomic oxygen, O(3P), in the nighttime mesosphere/ lower thermosphere. It is known that  atomic oxygen plays crucial role in the physics, chemistry, and energy budget of the mesosphere and lower thermosphere. Recombination of atomic oxygen is an important heating mechanism while the dominant radiative cooling of the MLT is caused by the 15-μm radiation of carbon dioxide, CO2, excited by collisions with O(3P). Reliable retrievals of temperature, ozone, and other constituents also strongly depend on the knowledge of atomic oxygen. Also, it was recently found that collisions between OH(v) and O(3P) provide a nighttime source of O(1D). In this report based on their recent studies they show how this fast, multi-quantum, vibrational-to-electronic relaxation of OH(v) by O activates pathways that generate the 4.3-μm CO2 band emission, O2 Atmospheric band emission and, presumably, the NO 5.2-μm emission, linking these three non-LTE band emissions to the OH Meinel band system. Implications for interpretation of space observations of these emissions and retrieving of O(3P), O(1D), and OH were discussed.