HR: 17:35h
AN: SH14B-07 [Abstracts]
TI: Mutual Information as a Non-linear Measure of Correlation in Multi-point Measurements in the
Solar Wind
AU: Dendy, R O
EM: richard.dendy@ukaea.org.uk
AF: Culham Science Centre, Euratom/UKAEA Fusion,
Culham, Abingdon, OX14 3DB, United Kingdom
AU: * Wicks, R T
EM: R.Wicks@warwick.ac.uk
AF: Centre for Fusion, Space and Astrophysics, Physics Dept., Univ. of Warwick, Coventry, CV4
7AL, United Kingdom
AU: Chapman, S C
EM: S.C.Chapman@warwick.ac.uk
AF: Centre for Fusion, Space and Astrophysics, Physics Dept., Univ. of Warwick, Coventry, CV4
7AL, United Kingdom
AB:
With increasing numbers of spacecraft in the solar wind new techniques for analyzing multi-spacecraft data are in
demand. We discuss techniques for implementing mutual information and present results obtained for
correlation of fluctuations in magnetic field, proton density and velocity between the WIND and ACE spacecraft at
the minimum and maximum of the last solar cycle. The magnetic field, particle density and velocity
measurements, as well as derived quantities such as Els\"{a}sser variables, are compared between ACE and
WIND and correlation length scales are calculated. Linear cross correlation is also used as a comparison,
indicating the degree to which non-linear and linear correlations differ, and the effect of the solar cycle is
investigated.
Mutual information shows a clear difference between the density and magnetic field measurements, which is
harder to discern from the linear correlation. The effect of the solar driver is also clear in the mutual information
measurements and the increase in scale length due to either solar coronal structure imposed on the solar wind,
or non-universal turbulence is measured.
DE: 2164 Solar wind plasma
DE: 3235 Persistence, memory, correlations, clustering (3265, 7857)
DE: 3270 Time series analysis (1872, 4277, 4475)
DE: 4475 Scaling: spatial and temporal (1872, 3270, 4277)
DE: 7839 Nonlinear phenomena (4400, 6944)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting