Astroclimate measurements on several points over Eastern hemisphere in 2-mm and 3-millimeter atmospheric transparency windows using tipping radiometer

We are presenting results of the atmospheric propagation observations which our research group has been conducting since 2012. Over this time, we have gathered statistical data of atmospheric propagation over a number of sites which possibly can be used for radio astronomical observations in the millimetre and sub-millimetre bandwidths. The Zenith opacity was studied by the atmospheric dip method in the 3 mm and 2 mm atmospheric windows. The dataset is recommended to use for estimation of atmospheric propagation for the purpose of radio astronomy and telecommunications.

The “tau-meter” (named MIAP-2) allows us to estimate an integral absorption by using the atmospheric dip method. The hardware includes a radiometric system comprising two self-contained radiometers operating in two different bands of 84-99 GHz (λ ~ 3 mm) and 132-148 GHz (λ ~ 2 mm), a rotary support, a control, and a firmware system. The radiometers work in modulation mode within 36 Hz modulation frequency. Floating mirror allows radiometer to scan the sky in the interval of 0 – 88.5 elevation angles (6 total). The output record contains the voltages of synchronous detector for each angle in 2 wavebands. The voltage is proportional to brightness temperature of the sky in corresponding waveband. (It has negative value for technical reasons.)

The dataset contains raw data observed by radiometer: Local date and time, a several detector voltages on different elevation angles for 2 wavebands, as well as service information header. The first 6 columns contain optical depth calculated by old method and it’s no more used in data processing since the new algorithm has been invented in 2018.