Abstract—Variations of the geomagnetic field and F2-layer critical frequency in the range of periods of planetary waves in winter season are analyzed. The measurements were conducted by a magnetometer and a vertical radio sounding ionosonde at the nearby Belsk and Warsaw stations and provided the records of the ionospheric current variations in the lower ionosphere and plasma density variations in the upper ionosphere, respectively. Spectral estimation is carried out for the winter seasons of 2018–2019 and 2014–2015 when solar activity was low and high, respectively. It is established that practically synchronous variations in the above range of period are present in the records by the ground magnetic station and in the ionosonde measurements of the F2 layer critical frequency. The spectra of the time variations of the geomagnetic field and F2-layer critical frequency in the period range of planetary waves in winter season contain the harmonic components associated with solar activity and with quasi-16-day and quasi-10-day planetary waves. The mechanism of the formation of the 16- and 10-day variations in the upper ionosphere is proposed.