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We study solar modulation of galactic cosmic rays (GCRs) during the deepsolar minimum, including the declining phase, of solar cycle 23 and compare theresults of this unusual period with the results obtained during similar phasesof the previous solar cycles 20, 21, and 22. These periods consist of twoepochs each of negative and positive polarities of the heliospheric magneticfield from the north polar region of the Sun. In addition to cosmic ray data,we utilize simultaneous solar and interplanetary plasma/field data includingthe tilt angle of the heliospheric current sheet. We study the relation betweensimultaneous variations in cosmic ray intensity and solar/interplanetaryparameters during the declining and the minimum phases of cycle 23. We comparethese relations with those obtained for the same phases in the three previoussolar cycles. We observe certain peculiar features in cosmic ray modulationduring the minimum of solar cycle 23 including the record high GCR intensity.We find, during this unusual minimum, that the correlation of GCR intensity ispoor with sunspot number (R = -0.41), better with interplanetary magnetic field(R = -0.66), still better with solar wind velocity (R = -0.80) and much betterwith the tilt angle of the heliospheric current sheet (R = -0.92). In our view,it is not the diffusion or the drift alone, but the solar wind convection isthe most likely additional effect responsible for the record high GCR intensityobserved during the deep minimum of solar cycle 23.

Solar Modulation of Cosmic Rays during the Declining and Minimum Phases of Solar Cycle 23: Comparison with Past Three Solar Cycles