Microwave spectroradiometer complex for remote study of the stratosphere thermal structure

We describe a microwave spectroradiometer for thermal sensing of the stratosphere in the molecular oxygen lines located on the slope of a 5-mm band. An uncooled low-noise high-frequency amplifier ensures the device noise temperature 1400 K. The frequency resolution of the used filtering analyzer varies from 0.5 MHz at the center of the line to 15 MHz at its boundary. The through calibration of the spectroradiometer is performed by an electrically controlled noise generator on the basis of the Schottky-barrier diode. The accuracy of the temperature recovery in the altitude range 20–55 km is estimated from the results of surface measurements of the atmospheric emission in the line with a central frequency of 53.0669 GHz. Model calculations based on the Bayesian approach show that the temperature-recovery accuracy no worse than 10 K for the confidence interval 95% can be achieved during an observation period of about half an hour.