Abstract: The Manaus region is surrounded by a vast expanse of tropical forest, exhibiting a complex interplay of geographical, climatic, and ecosystem factors that render it unique. The forest naturally emits a substantial amount of biogenic volatile organic compounds (BVOCs), frequently interacting with anthropogenic air pollution originating from the city of Manaus, significantly favoring the production of O3 in downwind regions of the city. According to Nascimento et al. (2022), the peak O3 concentration is observed southwest of Manaus, reaching approximately 47 ppbv at 2:00 PM (local time – UTC-4), with approximately 150-200 km from the city and in the direction of the prevailing wind. Conversely, in the center of Manaus during the same timeframe, O3 concentrations were observed to be close to 10 ppbv. For the calibration and validation of simulations using WRF-Chem, data from stations in the Green Ocean Amazon experiment (GoAmazon 2014–2015) were employed, including a total of 4 stations in addition to the Amazon Tall Tower Observatory (ATTO-T0a). In this context, tracking and analyzing the plume produced in the urban center of Manaus and its dispersion into pasture and forest regions at different times reveal variations in O3 concentrations. Air masses leaving Manaus at 7:00 AM (local time) reach their maximum development (~55 ppbv) at 3:00 PM (local time) due to a significant amount of available solar radiation during their transit. Conversely, air masses leaving later exhibit lower development in O3 production. To better understand the dynamics and photochemistry of O3 production in the Amazon region, experiments utilizing the WRF-Chem and CLASS (Chemistry Land-surface Atmosphere Soil Slab) models are being developed and investigated. To assess how radiation interacts in the O3 formation process, maintaining a fixed radiation value, numerical experiments with the WRF-Chem model have been chosen. Additionally, sensitivity experiments with the CLASS model, focusing on regions within the atmospheric boundary layer and modifying Nitrogen Oxide (NOx = NO+NO2) and Isoprene concentration values, aim to investigate how both compounds influence O3 production both in the city of Manaus and southwest of the urban center, where O3 concentration is higher.

Keywords: Ozone, Photochemistry, WRF-CHEM, CLASS model, Amazon region.