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Assessment of planetary boundary layer schemes of the WRF-Chem model in the simulation of carbon monoxide dispersion in the urban area of Quito, Ecuador

Abstract:

In tandem with emissions, the dynamics of the Planetary Boundary Layer (PBL) strongly define the concentration of pollutants in the atmosphere. The PBL parameterization schemes of numerical models need to be assessed to identify which one provides the best performance, especially in places with such complex topography as the Andean region of Ecuador. For this purpose, the dispersion of carbon monoxide (CO) in Quito (northern Ecuador, 2800 masl) during October 2014 was simulated using the Eulerian Weather Research and Forecasting with Chemistry (WRF-Chem V3.2) model, under 5 PBL schemes: 1. Yonsei University, YSU; 2. Mellor-Yamada-Janjic, MYJ; 3. Quasi-Normal Scale Elimination, QNSE; 4. Mellor-Yamada Nakanishi and Niino Level 2.5, MYN; and 5. BouLac PBL, BL. Simulations were performed using a domain with high spatial resolution (1 km) and results were compared with records from five air quality stations. On average, the percentage of days positively captured by modeling, for maximum CO concentrations over both 1-hour and 8-hour periods, was highest for QNSE (78.9%) and MYJ (76.8%), both 1.5 order local schemes. This assessment should be done for other periods, pollutants and meteorological variables.