Vol. 14, issue 08, article # 6

Abstract:

Horizontal variations of atmospheric refraction (VARs) are sought and analyzed based on the data obtained in the over-two-year photoelectric measurements of temporal parameters of moving images of stars passing at different zenith angles (from 30 to 90 degrees) across the first meridian. The all-year-present horizontal VARs with characteristic amplitudes of some angular seconds have been recorded. The statistical analysis for these VARs and qualitative analysis of their power spectra calculated with the Deeming method are made in the range of periods from tens seconds to tens of minutes. The spectra display two stable peaks with periods of 1 and 2 minutes, becoming more pronounced when approaching sunset. A number of peculiarities in minutes-long periodic VAR components manifesting themselves in essential dependence of the spectra type on the path inclination and north-southern orientation, as well as on season, have been revealed. At the zenith angles from 30 to 70-75 degrees southward from the zenith during near-equinox seasons and in summer, the spectra exhibit one distinct peak in the two-minute periods region. The amplitude of this peak sharply increases with the decrease in the path inclination angle. In the near-zenith zone of 75-90 degrees on the same side from zenith the two-minute peak is not observed, but in the winter-spring season similar peak here manifests itself in the region of one-minute periods. On the northern side (altitudes of 67-90 degrees) both minute-periodic peaks practically are not observed during all seasons. The possible source of the VAR studied is briefly discussed.