  We have studied the 27-day variations and their harmonics of the galactic
cosmic ray (GCR) intensity, solar wind velocity, and interplanetary magnetic
field (IMF) components in the recent prolonged solar minimum 23 24. The time
evolution of the quasi-periodicity in these parameters connected with the Suns
rotation reveals that their synodic period is stable and is aprox 26-27 days.
This means that the changes in the solar wind speed and IMF are related to the
Suns near equatorial regions in considering the differential rotation of the
Sun. However, the solar wind parameters observed near the Earths orbit provide
only the conditions in the limited local vicinity of the equatorial region in
the heliosphere (within in latitude). We also demonstrate that the observed
period of the GCR intensity connected with the Suns rotation increased up to
aprox 33-36 days in 2009. This means that the process driving the 27-day
variations of the GCR intensity takes place not only in the limited local
surroundings of the equatorial region but in the global 3-D space of the
heliosphere, covering also higher latitude regions. A relatively long period (
aprox 34 days) found for 2009 in the GCR intensity gives possible evidence of
the onset of cycle 24 due to active regions at higher latitudes and rotating
slowly because of the Suns differential rotation. We also discuss the effect of
differential rotation on the theoretical model of the 27-day variations of the
GCR intensity.
