  A major discovery of Parker Solar Probe (PSP) was the presence of large
numbers of localized increases in the radial solar wind speed and associated
sharp deflections of the magnetic field - switchbacks (SB). A possible
generation mechanism of SBs is through magnetic reconnection between open and
closed magnetic flux near the solar surface, termed interchange reconnection
that leads to the ejection of flux ropes (FR) into the solar wind. Observations
also suggest that SBs undergo merging, consistent with a FR picture of these
structures. The role of FRs merging in controlling the structure of SB in the
solar wind is explored through direct observations, through analytic analysis,
and numerical simulations. Analytic analysis reveals key features of the
structure of FR and their scaling with the heliocentric distance R that are
consistent with observations and that reveal the critical role of merging in
controlling the SB structure. FR merging is shown to be energetically favorable
to reduce the strength of the wrapping magnetic field and drive the observed
elongation of SBs. A further consequence is the resulting dominance of the
axial magnetic field within SBs that leads to the characteristic sharp rotation
of the magnetic field into the axial direction at the SB boundary that is
revealed in observations. Finally, the radial scaling of the SB area in the FR
model of SBs suggests that the observational probability of SB identification
should be insensitive to R, which is consistent with the most recent
statistical analysis of SB observations from PSP.
