Ag. Kraabol et al., Modelling chemistry in aircraft plumes 1: comparison with observations andevaluation of a layered approach, ATMOS ENVIR, 34(23), 2000, pp. 3939-3950
An expanding plume model with chemistry has been used to study the chemical
conversion of nitrogen oxides to reservoir species in aircraft plumes. The
model represents the plume by several circular or cylindrical layers in or
der to give a more detailed description of the chemical evolution in the pl
ume. Model simulations of plumes from two B747 aircraft monitored during th
e POLINAT measurement campaigns in winter 1994 and summer 1995 were perform
ed. The NO, emission indices were 12.5 and 26.1g kg(-1), respectively. The
chemical evolution was followed during the phase dominated by the aircraft-
induced dispersion (vortex regime), and in the atmospheric-induced dispersi
on regime up to 15 h. The results were compared to observations of NO, HNO3
, HNO2 and CO2 taken within the trailing vortices. The modelled values were
in broad agreement with the observations. With a NOx emission index of 26.
1 g kg(-1), 60% remained as NOx after 15 h at 50 degrees N under summer con
ditions for emissions at 07 UT. This amount decreased to 40% when a one-lay
ered plume was considered, suggesting that the distribution of NO, leads to
different oxidising potentials which again influenced the plume chemistry.
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