Distribution and Seasonal Variability of Ozone and Carbon Monoxide over the Tropics with 20 Years of Measurements.

Abstract:

Tropospheric ozone acts to control the oxidizing capacity of the atmosphere, but also it is a harmful pollutant for humans and plants in the lower troposphere, and a greenhouse gas in the upper troposphere. Tropics show particular interest as they receive maximum sunshine leading to active photochemistry, responsible for ozone production. This photochemistry is associated with many sources of emissions from fires, and activities of megacities constantly increasing, causing critical pollution. Natural sources (lightning, soil emissions) can also contribute to changes in the distributions of chemical compounds. Even though the tropics may play an essential role in global warming, the region is poorly documented with in situ observations of trace gases.

In this study, we investigate the distribution and seasonal variability of ozone and carbon monoxide observed by aircraft (IAGOS) and satellite (IASI) measurements in order to suggest processes that affect it. We also highlight anomalies (respect to the seasonal background) for different time periods and areas over the tropics. We focus on emissions, both anthropogenic and natural, circulation patterns, and stratosphere to troposphere exchange. For instance we estimate pollution origin (anthropogenic vs biomass burning) on carbon monoxide measurements using SOFT-IO tool. This way we plan to determine transport processes and emissions that most likely affect CO and O3 anomalies.