Consistent Determination of the Integral Humidity and Effective Optical Depth of the Atmosphere in the Millimeter Wavelength Range Using Wideband Radiometers

This paper proposes, and practically implements, a technique for finding equivalent frequencies, which are attributed to the atmospheric optical depths measured by a two-channel wideband radiometric system in the millimeter wavelength range. Establishment of the equivalent frequency (averaged over the frequency response of the system) in the corresponding atmospheric transparency window makes it possible to relate wideband measurements of the optical depth with narrowband radiometric measurements used in standard calculations of integral humidity. The search for equivalent frequencies is based on a comparison of experimental data on the effective transparency in the millimeter wavelength range and integral humidity of the atmosphere by simulation of a real atmosphere using the MPM Liebe model. The developed method of consistent determination of humidity and transparency of the atmosphere in the millimeter wavelength range can be used for both millimeter-wave radioastronomy and high-performance space telecommunications. In particular, the method specifies the spectral characteristics of the measured atmospheric transparency for the studied radio astronomy site and estimates the astroclimate conditions.