Comparison of Ambient Ratio Method and Ozone Limiting Method for determining NO_2 Concentrations in the Athabasca Oil Sands Region

摘要

In the Athabasca Oil Sands region of Alberta, Canada, a tiered approach has been adopted to model nitrogen dioxide (NO_2) emissions. This multi-tier approach arranged in order from most conservative to least conservative starts with the Total Conversion Method followed by the Plume Volume Molar Ratio Method (PVMRM) then the RIVAD/ARM3 Chemical Formulation in CALPUFF then the Ozone Limiting Method (OLM) and finally the Ambient Ratio Method (ARM). Typically ARM has been chosen over OLM for air assessments in the Oil Sands. In this study 2006 emissions scenario for the Athabasca Oil Sands Region was simulated using the CALPUFF model in 3-d mode. Ground-level concentrations of NO_2 were predicted using ARM and OLM at monitoring stations. Statistical parameters like Normalised Mean Square Error (NRMSE) and Fraction Bias (FB) were then used to assess the performance of ARM and OLM at the monitoring stations. In this study the methodology used to develop the non-linear NOx to NO_2 conversion ratio that is used to calculate NO_2Concentrations using ARM is presented. The study also shows the results of the model performance at monitoring stations using ARM and OLM.