Home – Home – Jornals – Atmospheric and Oceanic Optics 2026 number 2

In order to study the dynamics of the Earth's atmosphere, it is of interest to examine the frequency content of geomagnetic field variations in the range of the sixteen-day atmospheric planetary wave period (from 14.5 to 18 days). The spectra of Earth's magnetic field variations recorded between 2000 and 2023 at three European mid-latitude magnetic observatories, the Belsk Observatory (eastern Europe), the Furstenfeldbruck Observatory (central Europe), and the Dourbes Observatory (western Europe), were analyzed. Using the Lomb-Scargle periodogram method, harmonics associated with the modulation effect of long-period variations and tidal effects were identified in the spectrum in the range from 14.5 to 18 days. The analysis showed that the spectral content of geomagnetic variations does not depend on the longitude of the observation point (the points are located at approximately the same latitude). Spectral harmonics caused by the modulation wave with a semiannual variation of the second harmonic of the sunspot rotation cycle and the declination tidal were identified. For the M_sf tidal wave, harmonics were identified due to the modulation effect of the 11-year solar activity cycle (Schwabe), the fourth harmonic of the 22-year solar activity cycle, and annual and semiannual variations. Spectral harmonics are clearly distinguished in the spectra, whose periods correspond to the modulation effect of the 11-year solar activity cycle, the fourth harmonic of the 22-year solar activity cycle, and annual and semiannual variations on the 16-day planetary wave. The spectral analysis results confirm the influence of processes observed in the lower neutral atmosphere on the dynamics of the upper atmosphere. The results can be used to develop atmospheric dynamics models.