Statistical characteristics of the heliospheric plasma and magnetic field at the earth’s orbit during four solar cycles 20-23

A. V. Dmitriev, A. V. Suvorova, I. S. Veselovsky

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

21 Scopus citations

Abstract

The review presents analysis and physical interpretation of available statistical data about solar wind plasma and interplanetary magnetic field (IMF) properties as measured in-situ at 1 A.U. by numerous space experiments during time period from 1964 to 2007. The experimental information have been collected in the OMNI Web/NSSDC data set of hourly averaged heliospheric parameters for last four solar cycles from 20th to 23rd. We studied statistical characteristics of such key heliospheric parameters as solar wind proton number density, temperature, bulk velocity, and IMF vector as well as dimensionless parameters. From harmonic analysis of the variations of key parameters we found basic periods of 13.5 days, 27 days, 1 year, and ~11 years, which correspond to rotation of the Sun, Earth and to the solar cycle. We also revealed other periodicities such as specific five-year plasma density and temperature variations, which origin is a subject of discussion. We have found that the distribution of solar wind proton density, temperature and IMF is very close to a log-normal function, while the solar wind velocity is characterized by a very broad statistical distribution. Detailed study of the variability of statistical distributions with solar activity was performed using a method of running histograms. In general, the distributions of heliospheric parameters are wider during maximum and declining phase of the solar cycle. More complicated behavior was revealed for the solar wind velocity and temperature, which distribution is characterized by two- or even tree-peak structure in dependence on the phase of solar cycle. Our findings support the concepts of solar wind sources in the open, closed and intermittent magnetic regions on the Sun.

Original languageEnglish
Title of host publicationHandbook on Solar Wind
Subtitle of host publicationEffects, Dynamics and Interactions
PublisherNova Science Publishers, Inc.
Pages81-144
Number of pages64
ISBN (Electronic)9781613249765
ISBN (Print)9781606925720
StatePublished - 1 Jan 2009

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