06 May 2022
06 May 2022
Status: a revised version of this preprint is currently under review for the journal ACP.

Measurement report: Evolution and distribution of NH3 over Mexico City from ground-based and satellite infrared spectroscopic measurements

Beatriz Herrera1,2,3, Alejandro Bezanilla1, Thomas Blumenstock4, Enrico Dammers5, Frank Hase4, Lieven Clarisse6, Adolfo Magaldi7, Claudia Rivera1, Wolfgang Stremme1, Kimberly Strong3, Camille Viatte8, Martin Van Damme6,9, and Michel Grutter1 Beatriz Herrera et al.
  • 1Instituto de Ciencias de la Atmósfera y Cambio Climático, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico
  • 2Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, M1C 1A4, Canada
  • 3Department of Physics, University of Toronto, Toronto, M5S 1A7, Canada
  • 4Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany
  • 5Climate, Air and Sustainability (CAS), Netherlands Organisation for Applied Scientific Research (TNO), Utrecht, Netherlands
  • 6Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (SQUARES), Université libre de Bruxelles (ULB); Brussels B-1050, Belgium
  • 7ENES Juriquilla, Universidad Nacional Autónoma de México, Querétaro, 762630, Mexico
  • 8LATMOS/IPSL, Sorbonne Université, UVSQ, CNRS, Paris, France
  • 9Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium

Abstract. Ammonia (NH3) is the most abundant alkaline compound in the atmosphere, with consequences for the environment, human health, and radiative forcing. In urban environments, it is known to play a key role in the formation of secondary aerosols through its reactions with nitric and sulphuric acids. However, there are only a few studies about NH3 in Mexico City. In this work, atmospheric NH3 was measured over Mexico City between 2012 and 2020 by means of ground-based solar absorption spectroscopy using Fourier transform infrared (FTIR) spectrometers at two sites (urban and remote). Total columns of NH3 were retrieved from the FTIR spectra and compared with data obtained from the Infrared Atmospheric Sounding Interferometer (IASI) satellite instrument. The diurnal variability of NH3 differs between the two FTIR stations and is strongly influenced by the urban sources. Most of the NH3 measured at the urban station is from local sources, while the NH3 observed at the remote site is most likely transported from the city and surrounding areas. The evolution of the boundary layer and the temperature play a significant role in the recorded seasonal and diurnal patterns of NH3. Although the vertical columns of NH3 are much larger at the urban station, the observed annual cycles are similar for both stations, with the largest values in the warm months, such as April and May. The IASI measurements underestimate the FTIR NH3 total columns by an average of 32.2 ± 27.5 % but exhibit similar temporal variability. The NH3 spatial distribution from IASI shows the largest columns in the northeast part of the city. In general, NH3 total columns over Mexico City exhibited an average annual increase of 92 ± 3.9 x 1013 molecules/cm2 yr (urban) and 8.4 ± 1.4 x 1013 molecules/cm2 yr (remote) was observed in Mexico City at both FTIR stations and a decadal increase of 62 % with IASI data.

Beatriz Herrera et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-217', Anonymous Referee #1, 28 May 2022
    • AC1: 'Reply on RC1', Beatriz Herrera, 21 Sep 2022
  • RC2: 'Comment on acp-2022-217', Anonymous Referee #1, 12 Jul 2022
    • AC2: 'Reply on RC2', Beatriz Herrera, 21 Sep 2022
  • RC3: 'Comment on acp-2022-217', Anonymous Referee #2, 07 Aug 2022
    • AC3: 'Reply on RC3', Beatriz Herrera, 21 Sep 2022

Beatriz Herrera et al.

Data sets

MODIS active fire snapshots Earth Observing System Data and Information System (EOSDIS)

IASI ANNI-NH3-v3 L2 data ULB-LATMOS team

meteorological data for UNAM and Altzomoni stations Red Universitaria de Observatorios Atmosfericos (RUOA)

Beatriz Herrera et al.


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Short summary
This work investigates atmospheric ammonia (NH3), a key trace gas with consequences for the environment and human health, in Mexico City. The results from the ground-based and satellite instruments show the variability and spatial distribution of NH3 over this region. NH3 in Mexico City has been increasing for the past ten years and most of its sources are urban. This work contributes to a better understanding of NH3 sources and variability in urban and remote areas.