Impact of boreal wildfires on air quality: from regional to hemispheric scales
Résumé
Wildfires are a significant source of atmospheric pollutants, including greenhouse gases and
aerosols. Among the emitted species, most have long enough lifetimes to be transported over
thousands of kilometres. Boreal wildfires are particularly intense and have been shown to
strongly influence the interannual variability of several atmospheric pollutants (carbon
monoxide, CO, and aerosols) in the remote Northern Hemisphere. With a fire risk increasing
and fire seasons lengthening as a result of climate change, it is all the more critical to better
estimate the large-scale impact from these large events.
Here, the impact of boreal fires on regional air quality in Canada and in Europe (after longrange
transport) is estimated using a combination of satellite data analysis (IASI for CO,
MODIS AOD and CALIOP lidar profiles for aerosols) and modelling with the CHIMERE
regional chemistry-transport model. The fire emissions are calculated using the APIFLAME
emission model, including in particular a better representation of the potential burning of the
ground organic layer. Their variability will first be described for the time period 2013-2015.
The performance of the model to simulate the local pollution levels and the influence from
long-range transport (in the mid and high latitudes) will be discussed, focusing on the summer
of 2013. The chemical evolution of the main plumes will then be evaluated using observations
of more reactive trace gases (NH3 from IASI, NO2 from GOME-2).