Carbon monoxide mixing ratio in the mesosphere derived from ground‐based microwave measurements

High‐resolution ground‐based measurements have been made of the J = 0 → 1 and the J = 1 → 2 rotational transitions of carbon monoxide in the earth’s atmosphere. These transitions, which occur at frequencies near 115 and 230 GHz, were observed in absorption against the solar continuum. The two absorption profiles have been used to derive the CO mixing ratio as a function of altitude between 50 and 80 km in the atmosphere.