Soot and SO2 contribution to the supersites in the MILAGRO campaign from elevated flares in the Tula Refinery
This work presents a simulation of the plume tra- 1 Introduction jectory emitted by flaring activities of the Miguel Hidalgo Refinery in Mexico. The flame of a representative sour gas flare is modeled with a CFD combustion code in order to estimate emission rates of combustion by-products of inter- est for air quality: acetylene, ethylene, nitrogen oxides, car- bon monoxide, soot and sulfur dioxide. The emission rates of NO2 and SO2 were compared with measurements ob- tained at Tula as part of MILAGRO field campaign. The rates of soot, VOCs and CO emissions were compared with es- timates obtained by Instituto Mexicano del Petro ́leo (IMP). The emission rates of these species were further included in WRF-Chem model to simulate the chemical transport of the plume from 22 to 27 March of 2006. The model presents re- liable performance of the resolved meteorology, with respect to the Mean Absolute Error (MAE), Root Mean Square Er- ror (RMSE), mean bias (BIAS), vector RMSE and Index of Agreement (IOA). WRF-Chem outputs of SO2and soot were compared with surface measurements obtained at the three supersites of MI- LAGRO campaign. The results suggest a contribution of Tula flaring activities to the total SO2 levels of 18 % to 27 % at the urban supersite (T0), and of 10 % to 18 % at the suburban su- persite (T1). For soot, the model predicts low contribution at the three supersites, with less than 0.1 % at three supersites. According to the model, the greatest contribution of both pol- lutants to the three supersites occurred on 23 March, which coincides with the third cold surge event reported during the campaign.