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Conference papers

Distribution and variability of NH3 in Mexico City from ground-based FTIR and space-based IASI measurements

Abstract : The most abundant alkaline compound in the atmosphere is ammonia (NH3). This key gas is involved in several chemical reactions, especially those to neutralize acids. NH3 also contributes to aerosol formation and particulate matter, with potential consequences to the environment, human health, and radiative forcing. NH3 is primarily emitted by agricultural sources; however, it is also present in urban environments like Mexico City, one of North America’s biggest cities with a high population density and major pollution episodes. This work investigates the temporal and spatial variability of NH3, including some enhancement events, to address the lack of information available in this region. Using solar absorption ground-based measurements from two Fourier transform infrared (FTIR) spectrometers located in urban and rural areas of Mexico City, total columns NH3 were retrieved using the PROFFIT9 algorithm. These measurements were complemented by satellite data products over the Mexico City area from the Infrared Atmospheric Sounding Interferometer (IASI) instrument on board the MetOp-A platform. The ground-based results reveal similarities in the seasonal variability of NH3 between the urban and rural sites and exhibit temperature dependence, with the highest columns during the warmest months and the lowest columns during the cold and rainy seasons. In contrast, the diurnal pattern of NH3 present remarked differences due to the meteorology and the surrounding urban sources. Both sites showed an increasing trend of NH3 through the most recent years. The IASI total columns of NH3 are smaller than the urban FTIR columns (using coincidence criteria of 20 km and 80 min), but exhibit similar seasonal variability and provide information about the spatial distribution of NH3 around the Mexico City region, identifying the highest concentrations in the northeast area. Back-trajectory analysis was used to confirm the influence of this area in the observed NH3 enhancement events. These findings provide insight into atmospheric processes involving NH3 and can be used to improve air quality models.
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Conference papers
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https://hal-insu.archives-ouvertes.fr/insu-03023709
Contributor : Catherine Cardon <>
Submitted on : Wednesday, November 25, 2020 - 2:45:14 PM
Last modification on : Saturday, December 12, 2020 - 12:10:12 PM

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  • HAL Id : insu-03023709, version 1

Citation

Beatriz Herrera, Michel Grutter, Wolfgang Stremme, Adolfo Magaldi, Kimberley Strong, et al.. Distribution and variability of NH3 in Mexico City from ground-based FTIR and space-based IASI measurements. AGU Fall Meeting 2020, Dec 2020, Online, United States. ⟨insu-03023709⟩

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