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Direct observations over the past four centuries show that the number ofsunspots observed on the Sun's surface vary periodically, going throughsuccessive maxima and minima. Following sunspot cycle 23, the Sun went into aprolonged minimum characterized by a very weak polar magnetic field and anunusually large number of days without sunspots. Sunspots are stronglymagnetized regions and are generated by a dynamo mechanism which recreates thesolar polar field mediated via plasma flows. Here we report results fromkinematic dynamo simulations which demonstrate that a fast meridional flow inthe early half of a cycle, followed by a slower flow in the latter half,reproduces both the characteristics of the minimum of sunspot cycle 23 - alarge number of spotless days and a relatively weak polar field. Our modelpredicts that, in general, very deep minima are associated with weak polarfields. Sunspots govern the solar radiative energy and radio flux, and inconjunction with the polar field, modulate the solar wind, heliospheric openflux and consequently cosmic ray flux at Earth; our results therefore provide acausal link between solar internal dynamics and the atypical values of theseheliospheric forcing parameters during the recently concluded solar minimum.

The unusual minimum of sunspot cycle 23 a consequence of Sun's meridional plasma flow variations