A method for the determination of high‐altitude water‐vapor abundance from ground‐based microwave observations

The microwave resonance line at 22,235 Mc/s (λ = 1.35 cm) arising from uncondensed H2O in the terrestrial atmosphere is examined in detail as a means of providing easily obtained data on the physical structure of the atmosphere. It is shown that the line profile is drastically influenced by the vertical distribution of H2O and that the anomalous abundance of uncondensed H2O above 15 to 20 km should be easily detected and monitored by ground-based passive microwave observations. The method, capable of 24 hours per day operation, can be used to determine abundance changes on a time scale as short as several seconds, if necessary, and to reveal horizontal fine structure with a resolution of 150 meters at an altitude of 30 km with a 10-foot parabolic receiving antenna. Other atmospheric constituents that have microwave resonance spectrums, for example O3, are amenable to study by this procedure.