In-Situ Monitoring and Origins of Increased Air Pollutants in the North Pacific Upper Troposphere: Insights from PGGM/IAGOS Carbon Monoxide Measurements aboard the China Airlines A340-300 Commercial Aircraft (July 2012 - February 2013)

Abstract This research focuses on regular in-situ measurements of carbon monoxide (CO) in the upper troposphere over the North Pacific. Utilizing the Pacific Greenhouse Gases Measurement (PGGM)/In-Service Aircraft for a Global Observing System (IAGOS) air-based measurement project, our study conducted measurements aboard a commercial Airbus A340-300 (B18806) operated by China Airlines (CAL). Data collection spanned from July 2012 to February 2013.Our findings indicate a discernible increase in anthropogenic CO pollution in the North Pacific upper troposphere from 1991 to 2012. Comparison with NASA aircraft missions from 1991, 1994, and 2001 further substantiates this rise. Elevated CO concentrations (> 160 ppbv) were prominent in the summer months of July and August, followed by September, while concentrations were lower (< 100 ppbv) from October 2012 to February 2013.The results underscore effective vertical transport of ground-level anthropogenic pollutants to the upper troposphere. HYSPLIT model calculations affirm that Asian industrial regions at ground level are the primary sources of CO pollution in the downwind areas of the North Pacific upper troposphere.This study enhances our understanding of temporal variations and sources of CO pollution in this specific region, utilizing routine in-situ measurements on commercial aircraft to contribute valuable insights to air quality and pollution transport dynamics.