Biomass burning emissions are distributed over different altitude ranges.
Since the distribution over model levels is only calculated once per month using the gph field at that time, there will be small differences when the model is (re)started halfway a month. In cy3/chem/aero this has been solved by re-computing the altitude distibution every time step using the up-to-date gph.
Alternative is to use a standard atmospheric profile:
p = p0 * exp( -z/H ) ! Pa ; pressure as a function of altitude z (m)
H = 8e3 ! m ; scale height
p0 = 1e5 ! Pa ; surface pressure
This does not account for changes in pressure and temperature,
but this is probably not significant since the choices for height
distribution are not very accurate anyway.