title: Solar-wind proton anisotropy versus beta relation.
abstract: The present Letter puts forth a possible explanation for the outstanding problem of measured proton temperature anisotropy in the solar wind at 1 AU apparently being regulated by the mirror and oblique fire-hose instabilities. Making use of the fact that the local magnetic field intensity near 1 AU undergoes intermediate-scale temporal variations, the present Letter carries out the quasilinear analysis of the temperature anisotropy-driven instabilities with a time-varying local B field, assuming arbitrary initial temperature ratios and parallel betas. It is found that the saturated states in (β(∥), T(⊥)/T(∥)) space are bounded by the mirror and oblique fire-hose instabilities, which is superficially similar to the observation.
authors.affiliation: School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701, Korea.
authors.forename: Jungjoon
authors.initials: J
authors.lastname: Seough
authors.affiliation: School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701, Korea.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Yoon
authors.affiliation: School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701, Korea.
authors.forename: Khan-Hyuk
authors.initials: KH
authors.lastname: Kim
authors.affiliation: School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701, Korea.
authors.forename: Dong-Hun
authors.initials: DH
authors.lastname: Lee