Comments about the plots per hour:

The first pair of plots (USD volume per hour) show a maximum of tradeing volume
around 15:00 UTC (09:00 Central US time,  23:00 China time)
and a minimum  around 03:00 UTC (21:00  Central US time, 11:00 China time).  This may indicate that
most of the volume at Bitstamp is due to European traders, or perhaps to a mix of American traders
and arbitragers with China.  Hard to tell.

The shape of the USD volume plots is the same for Jan-Apr and May-Sep, but the latter has been
only 200 k$/hour while the former was about 450 k$/hour.  Given the overal price drop over the
period, it seems that the BTC volume has changed little.

The second set of plots seems to say that the average price change is nearly indepependent of the hour of
day.  The ups and down seem to be just artifacts of the relatively small sample (273 days).  That is, there
are no "bullish hours" not "bearish hours".

The third set of plots (RMS price change) has a minimum around 19:00 UTC, which is  China slumber time.
This is consistent with the claim that the price changes have been mostly defined by the Chinese
exchanges.

However, that effect is quite clear only on the first four months Jan--Apr,
while from May--Sep the volatility seems to be much smaller and nearly independent of
the hour of day.  This could mean that China is no longer defining the price --- but then,
neither is the West.  Perhaps the big traders who define the price, in China or in the West,
now use autonomous robots that work 24 hours a day.  Maybe.