Modelling of the vertical fluxes of nitric acid, ammonia, and ammonium nitrate

Results from numerical investigations regarding the exchange of HNO3, NH3, and NH4NO3 between the atmosphere and the biosphere are presented. The investigations were performed with a modified inferential method which is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions among these nitrogen compounds. This modified inferential method calculates the micrometeorological quantities (such as the friction velocity and the fluxes of sensible and latent heat), the height-invariant fluxes of the composed chemically conservative trace species with 'group' concentrations c(1)= (HNO3) + (NH4NO3) (total nitrate), c(2)=(NH3) + (NH4NO3) (total ammonia), and c(3) = (HNO3) - (NH3) as well as the fluxes of the 'individual' nitrogen compounds. The parameterization of the fluxes is based on the flux-gradient relationships in the turbulent region of the atmospheric surface layer. The modified i nferential method requires only the data of wind velocity, temperature, humidity and concentrations (HNO3, NH3, and NH4NO3) measured at a reference height by stations of a monitoring network.