The lowest threshold (t ¼ 0.5 mg/m3) was selected because it
corresponds approximately to the mean absolute error of NO2
predicted by AERIS (0.49 mg/m3) for a fully-described emission
scenario evaluated in Vedrenne et al. (2013). The other thresholds
are twofold and threefold this concentration value respectively. To
this respect, we considered the approach is adequate enough in
those cells below the first threshold, meaning that the accumulation
of error due to the independent use of TMs is analogous to the
error associated with the simultaneous use of TMs. Despite the fact