Revisiting regional and seasonal variations in decadal carbon monoxide variability: Global reversal of growth rate

Ankit Patel; Chinmay Mallik; Naveen Chandra; Prabir K Patra; Martin Steinbacher

doi:10.1016/j.scitotenv.2023.168476

Revisiting regional and seasonal variations in decadal carbon monoxide variability: Global reversal of growth rate

Sci Total Environ. 2024 Jan 20:909:168476. doi: 10.1016/j.scitotenv.2023.168476. Epub 2023 Nov 18.

Authors

Ankit Patel¹, Chinmay Mallik², Naveen Chandra³, Prabir K Patra⁴, Martin Steinbacher⁵

Affiliations

¹ Department of Atmospheric Science, Central University of Rajasthan, Ajmer 305801, India.
² Department of Atmospheric Science, Central University of Rajasthan, Ajmer 305801, India. Electronic address: chinmay.mallik@curaj.ac.in.
³ Research Institute for Global Change, JAMSTEC, Yokohama 2360001, Japan.
⁴ Research Institute for Global Change, JAMSTEC, Yokohama 2360001, Japan; Research Institute for Humanity and Nature, Kyoto, Japan.
⁵ Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Duebendorf, Switzerland.

PMID: 37984655
DOI: 10.1016/j.scitotenv.2023.168476

Abstract

Carbon monoxide (CO) is one of the important trace gases in the atmosphere capturing the evolution of chemical properties of the troposphere. Here we analyze the growth rates of CO during the period of 1991-2020 using in situ measurements from the World Meteorological Organization's (WMO) Global Atmospheric Watch (GAW) program. The analysis of trends has been done on different spatial and temporal scales. Our analysis supports the decline in the overall CO mixing ratios over the globe but inter-decadal and regional trend analysis has shown heterogeneous changes in the given period of study. On average, there has been a decrease of -16.22 ± 1.92 ppb and -4.5 ± 0.64 ppb observed at the sites in the northern hemisphere (NH) and southern hemisphere (SH), respectively. This decline occurred at rates of -0.80 ± 0.12 ppb yr^-1 in the NH and - 0.12 ± 0.03 ppb yr^-1 in the SH. Bifurcating the annual trends for seasonal analysis reveals the impact of emissions, chemistry and atmospheric transport on CO variation over different regional clusters of stations. Seasonal trend analysis provides further evidence regarding heterogeneous patterns in the South-East Asia region. Our study highlights a slowdown in CO decline during the 2011-2020 decade when compared to the rate of decrease observed in 2001-2010. This is inferred from the variability and much slower decline of CO emissions across different regions, contributing to a weakening in CO trends.

Keywords: Carbon monoxide; Emissions; Inter-decadal; Regional trend analysis; Trends.