ИСТИНА

Ground-based passive measurements of downwelling atmospheric radiation at ~110.836 GHz allow one to extract the spectra of ozone self-radiation (rotational transition J = 61,5 - 60,6) coming from the low stratosphere - middle mesosphere and retrieve vertical profiles of ozone concentration at these altitudes. Nowadays, there is a notable (several hundred kHz) ambiguity in determination of the resonance frequency of this important ozone line. We carried out long-term ground-based measurements of atmospheric microwave radiation in this range using upgraded apparatus with relativity high spectral resolution (~12 kHz). Obtained brightness temperature spectra allowed us to define the resonance frequency of this ozone line to be 110835.909±0.016 MHz. We verified that Doppler shift of frequency by meridional component of horizontal wind as well as variations of the tropospheric absorption had a little effect on the obtained result. The found value is 130 kHz less than laboratory measured one and differ from modern model calculations. Surprisingly, it is close to the results of early semiempirical calculations carried out more than 40 years ago. We discuss the applications where the knowledge about the resonance frequency of this ozone line with high precision can be important.