IASI Carbon Monoxide Global and Regional Trends over the period [2008 - 2022]

Carbon monoxide (CO) is a key atmospheric pollutant that is closely monitored for its role in
tropospheric chemistry as a modulator of the oxidizing capacity of the atmosphere. It is mainly
emitted into the atmosphere during combustion processes linked to anthropogenic activities
(heating, industry, transport) and during biomass combustion (natural fires or burning of agricultural
waste).

Since 2007, three IASI (Infrared Atmospheric Sounding interferometer) instruments have been
successively embarked on board of the polar-orbiting meteorological satellites Metop-A, -B and -C.
They provide a global and daily coverage of CO concentrations in the atmosphere, with two daily
overpasses (at 9:30 am and 9:30 pm local time). In February 2022, EUMETSAT reprocessed the whole
IASI CO dataset , providing a homogeneous record of CO, since the beginning of the mission.

In this study, and for the first time, we use this 15-years of continuous and homogenized dataset to
analyze the evolution of daytime CO concentrations from January 2008 to December 2022. The
Theil-Sen method is applied on the deseasonalized dataset in order to compute the slope of the
trend. The p-value of Sen’s Slope is determined by using the Mann-Kendall test.

Here, we analyze the evolution of CO concentrations on a global and regional scale, and show the
evolution of CO concentrations in each hemisphere and in specific regions of the world that are
sensitive to biomass fires (Central Africa, South America) and anthropogenic emissions (South and
East Asia, Europe and North America). The results are compared with the documented trends in
emission inventories.