  Parker Solar Probe (PSP) data recorded within a heliocentric radial distance
of 0.3 AU have revealed a magnetic field dominated by Alfv\'enic structures
that undergo large local variations or even reversals of the radial magnetic
field. They are called magnetic switchbacks, they are consistent with folds in
magnetic field lines within a same magnetic sector, and are associated with
velocity spikes during an otherwise calmer background. They are thought to
originate either in the low solar atmosphere through magnetic reconnection
processes, or result from the evolution of turbulence or velocity shears in the
expanding solar wind. In this work, we investigate the temporal and spatial
characteristic scales of magnetic switchback patches. We define switchbacks as
a deviation from the nominal Parker spiral direction and detect them
automatically for PSP encounters 1, 2, 4 and 5. We focus in particular on a
5.1-day interval dominated by switchbacks during E5. We perform a wavelet
transform of the solid angle between the magnetic field and the Parker spiral
and find periodic spatial modulations with two distinct wavelengths,
respectively consistent with solar granulation and supergranulation scales. In
addition we find that switchback occurrence and spectral properties seem to
depend on the source region of the solar wind rather than on the radial
distance of PSP. These results suggest that switchbacks are formed in the low
corona and modulated by the solar surface convection pattern.
