Inherent length scales of periodic mesoscale density structures in the
solar wind over two solar cycles
It is now well-established through multiple event and statistical
studies that the solar wind at 1 AU contains contains periodic,
mesoscale (L~100-1000Mm) structures in the proton
density. Composition variations observed within these structures and
remote sensing observations of similar structures in the young solar
wind indicate that at least some of these periodic structures originate
in the solar atmosphere as a part of solar wind formation. Viall et al.
 analyzed 11 years of data from the Wind spacecraft near L1
and demonstrated a recurrence to the observed length scales of periodic
structures in the solar wind proton density. In the time since that
study, Wind has collected 14 additional years of solar wind data, new
moment analysis of the Wind SWE data is available, and new methods for
spectral background approximation have been developed. In this study, we
analyze 25 years of Wind data collected near L1 and produce occurrence
distributions of statistically significant periodic length scales in
proton density. The results significantly expand upon the Viall et al.
 study, and further shows a possible relation of the length
scales to solar “termination” events.