Quantification on source/receptor relationship of primary pollutants and secondary aerosols from ground sources—Part I. Theory

A new algorithm has been derived for trajectory models to determine the transfer coefficient of each source along or adjacent to a trajectory and to calculate the concentrations of SO2, NOx, sulfate, nitrate, fine particulate matter (PM) and coarse PM at a receptor. The transfer coefficient tf (s m−1) is defined to be the ratio between the contributed concentration ΔC (μg m−3) to the receptor from a ground source and the emission rate of the source q (μg m−2 s−1) at a grid, i.e. tf≡ΔC/q. The model is developed by combining with a backward trajectory scheme and a circuit-typeʹs parameterization. First, the transfer coefficients of grids along or adjacent a back-trajectory are calculated. Then, the contributed concentration of each emission grid is determined by multiplying its emission rate with the transfer coefficient of the grid. Finally, the concentration at the receptor is determined by the summation of all the contributed concentrations within the domain of simulation.