  Mutual quasi-periodicities near the solar-rotation period appear in time
series based on the Earth's magnetic field, the interplanetary magnetic field,
and signed solar-magnetic fields. Dominant among these is one at 27.03 +/- 0.02
days that has been highlighted by Neugebauer, et al. 2000, J. Geophys. Res.,
105, 2315. Extension of their study in time and to different data reveals
decadal epochs during which the ~ 27.0 day, a ~ 28.3 day, or other
quasi-periods dominate the signal. Space-time eigenvalue analyses of time
series in 30 solar latitude bands, based on synoptic maps of unsigned
photospheric fields, lead to two maximally independent modes that account for
almost 30% of the data variance. One mode spans 45 degrees of latitude in the
northern hemisphere and the other one in the southern. The modes rotate around
the Sun rigidly, not differentially, suggesting connection with the subsurface
dynamo. Spectral analyses yield familiar dominant quasi periods 27.04 +/- 0.03
days in the North and at 28.24 +/- 0.03 days in the South. These are replaced
during cycle 23 by one at 26.45 +/- 0.03 days in the North. The modes show no
tendency for preferred longitudes separated by ~ 180 degrees.
