(1) Department of Physics and Astronomy, California State University, 18111 Nordhoff Street, Northridge, CA 91330-8268, USA;(2) Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
Abstract:
Principal components analysis (PCA) and independent component analysis (ICA) are used to identify global patterns in solar
and space data. PCA seeks orthogonal modes of the two-point correlation matrix constructed from a data set. It permits the
identification of structures that remain coherent and correlated or that recur throughout a time series. ICA seeks for maximally
independent modes and takes into account all order correlations of the data. We apply PCA to the interplanetary magnetic field
polarity near 1 AU and to the 3.25R⊙ source-surface fields in the solar corona. The rotations of the two-sector structures of these systems vary together to high
accuracy during the active interval of solar cycle 23. We then use PCA and ICA to hunt for preferred longitudes in northern
hemisphere Carrington maps of magnetic fields.