The Prelude to the Deep Minimum between Solar Cycles 23 and 24:   Interplanetary Scintillation Signatures in the Inner Heliosphere
  Extensive interplanetary scintillation (IPS) observations at 327 MHz obtained between 1983 and 2009 clearly show a steady and significant drop in the turbulence levels in the entire inner heliosphere starting from around ~1995. We believe that this large-scale IPS signature, in the inner heliosphere, coupled with the fact that solar polar fields have also been declining since ~1995, provide a consistent result showing that the buildup to the deepest minimum in 100 years actually began more than a decade earlier. 
P. Janardhan, Susanta Kumar Bisoi, S. Ananthakrishnan, M. Tokumaru and   K. Fujiki
astro-ph.SR physics.space-ph