Frequency distribution of Ohmic heating event energies for four different spatial box volumes V and five different temporal bin sizes τ. The temporal binning τ is color−coded and labeled in the figure. The spatial box sizes V are 0.29 Mm³, 0.97 Mm³, 2.31 Mm³, and 4.51 Mm³. The distribution with the smallest box size V is the group of lines starting at the smallest energies (to the left). For the two smallest binnings the number of events is large enough that the frequency size distribution is continuous. For the two larger binnings the distribution is interrupted owing to the low number of events. Overplotted is a power law with a slope of −1.2. The vertical dotted line indicates the typical nanoflare energy as predicted by Parker (1988). See Sect. 4.1.