Analysis of Aerosols in the Asian Monsoon Anticyclone as Observed by the Atmospheric Chemistry Experiment

Authors

M. Lecours, University of Waterloo
R. Dodangodage, University of Sri Jayewardenepura
C. D. Boone, University of Waterloo
P. F. Bernath, Old Dominion UniversityFollow

Document Type

Article

Publication Date

2025

DOI

10.1029/2025JD043839

Publication Title

Journal of Geophysical Research: Atmospheres

Volume

130

Issue

21

Pages

e2025JD043839

Abstract

During the Asian summer monsoon season, pollutants from the lower troposphere are transported through deep convection to the upper troposphere and lower stratosphere. Surface pollutants such as CO are transported upward and trapped in the anticyclone during this unique atmospheric phenomenon. Associated with the anticyclone is a layer of enhanced aerosols located near the tropopause often referred to as the Asian tropopause aerosol layer (ATAL). The chemical and physical properties of aerosols in the ATAL are not yet fully understood as direct observations of the aerosols are limited. The Atmospheric Chemistry Experiment (ACE) is a satellite mission that provides high-resolution infrared observations of atmospheric trace gases and aerosols. ACE observes chemical isolation in the anticyclone and identifies three main types of aerosols in the ATAL: solid ammonium nitrate (AN), sulfate aerosols, and ice. ACE observes four main features in the spectrum of AN; the previously known 831 cm⁻¹ feature and the first-ever identification of the spectral bands at 1,390–1,450 cm⁻¹, 3,080 cm^−¹, and 3,220 cm^−¹. Simulated spectra reproduce the 831 cm^−¹, 3,080 cm^−¹, and 3,220 cm^−¹ features well but the 1,390–1,450 cm^−¹ spectral feature is poorly reproduced. In rare circumstances, ACE observes aerosols similar to AN far outside of the monsoon region. In these aerosols the 3,080 cm^−¹ and 3,220 cm^−¹ features align well with AN observed in the ATAL. The 831 cm^−¹ feature is suppressed and shifted to 829 cm^−¹, suggesting that AN aerosols outside the ATAL are liquid, or potentially an alternative phase of AN.

Rights

© 2025. The Authors.

This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Data Availability

ACE-FTS volume mixing ratio, imager retrievals, and residual spectra can be accessed at https://databace.scisat.ca/level2/ace_v5.3/display_data.php (ACE-SOCws, 2025) (registration required).

Original Publication Citation

Lecours, M., Dodangodage, R., Boone, C. D., & Bernath, P. F. (2025). Analysis of aerosols in the Asian monsoon anticyclone as observed by the Atmospheric Chemistry Experiment. Journal of Geophysical Research: Atmospheres, 130(21), 1-15, Article e2025JD043839. https://doi.org/10.1029/2025JD043839

ORCID

0000-0002-1255-396X (Bernath)

Repository Citation

Lecours, M.; Dodangodage, R.; Boone, C. D.; and Bernath, P. F., "Analysis of Aerosols in the Asian Monsoon Anticyclone as Observed by the Atmospheric Chemistry Experiment" (2025). Chemistry & Biochemistry Faculty Publications. 376.
https://digitalcommons.odu.edu/chemistry_fac_pubs/376