4.3. Time of day
4.3.1. CH4 flux during the flooded growing period
CH4 fluxes vary considerably diurnally — they tend to be high in the daytime and low at night.
Figure 4.1 shows a typical diurnal pattern measured after the heading stage in two rice
paddies in temperate Japan (Minamikawa et al., 2012). The daily mean flux was obtained at
around 10:00 and around 19:00 at both sites. A similar diurnal pattern has also been
observed in tropical regions (e.g., in India: Adhya et al., 1994; Satpathy et al., 1997).