AERONOMIC RADIO SPECTROMETRY WITH CALIBRATION BY SIGNALS FROM VIRTUAL SOURCES

Abstract

Subject and Purpose. The work has been aimed at developing and implementing a novel method of aeronomic observations in the Earth's stratosphere, applicable in the microwave range of the electromagnetic spectrum. The research is centered on a study of the measurement errors arising when the method proposed is employed for observations of the ozone spectral line (142 GHz). Methods and Methodology. The method is based on a simplified calibration procedure, in what concerns the hardware and the technology employed. In contrast to the common calibration techniques using special-purpose sources of the reference signal, we suggest resorting to natural sources, like internal noise of the receiver and the thermal radiation from the Earth's surface and the lower atmospheric layer. The measurement errors (both calculated and evaluated experimentally) have been analyzed within standard mathematical statistics techniques. Results. The tests performed during observations of the spectral line (142 GHz) of atmospheric ozone allow considering the new method as a success. The estimated magnitude of the relative error specific to the observation method proposed does not exceed 1.5%. The experimental estimate accounting for all potential error sources does not exceed 5% (with a 1 hour accumulation period), which result corresponds to the current state of the art. Conclusions. The possibility of an essential simplification of the radio optical part of the spectrometer has been demonstrated. The novel calibration technique, as well as the technical implementation thereof, can be recommended as a basis for prospective spectrometers at microwave frequencies.

Keywords

• aeronomy
• ozone
• calibration
• millimeter wavelengths