The fluctuations of the lunar calendar made it ill fit for agriculture.  So we
have expressions like "hachijuu-hachiya", "nihyaku-touka" that count days from
the first day of spring.

The twenty-four semesters: 'risshun' ("start of spring"), 'usui' ("snow turns to
rain, ice to water"), 'keichitsu' ("hibernating animals come out"), etc. are
also based on the solar calendar.  'Setsubun' is the day before 'risshun' so its
is in a sense, the solar New Year's Eve.  ('Setsubun' is a general term meaning
"change of season" but the turn from winter to spring is most celebrated.)