Variations in Daily Maximum Areas and Longitudinal Widths of Solar Coronal Holes in 2017–2020

We considered coronal holes as a manifestation of the large-scale magnetic field Sun. The main goal this work was to study variations in largest areas and longitudinal widths solar observed daily polar mid-latitude zones on time scale 984 days. Statistical methods fast Fourier transform (FFT), wavelet transform, empirical mode decomposition (EMD) were used detect periodicity parameters. Long-term measured with periods 8–9, 13–15, 26–29 days detected three Sun: (north south) equatorial. obtained are most clearly visible at equatorial zone. In period 8–9 has weak amplitude. interpreted rotation six-, four-, two-sector structure field.