Current research projects

The main goal of our research is to integrate the growing wealth of surface, aircraft, and satellite observations of atmosphere trace constituents, with a particular focus on the satellite data, to obtain a more comprehensive understanding of the impact of pollution on the atmospheric environment. This includes better quantifying surface emissions of key atmospheric trace gases, characterizing their chemical transformation and export to the global atmosphere, and understanding how changes in the climate system will influence the global transport of these gases. Our primary tools are the GEOS-Chem global chemical transport model and its adjoint, which are employed for data assimilation and inverse modelling of the atmospheric data. Listed here are some of the current research projects in the group.

1) Investigation of the influence of long-range transport of pollution on air quality in the Arctic

The Arctic is a fragile ecosystem that is particularly sensitive to changes in the climate system and to the influence of anthropogenic pollution. We are using the GEOS-Chem global three-dimensional chemical transport model and its adjoint to exploit the new satellite measurements, together with existing surface measurements, to quantify the impact of intercontinental transport of pollution on the chemistry of the Arctic troposphere. In particular, we seek to better constrain the budget of ozone (O
3) and nitrogen oxides (NOx) in the Canadian Arctic to obtain an improved understanding of the factor controlling the seasonal dependence of the O3 and NOx budgets.

2) Interannual variability in long-range transport of pollution

We are using the GEOS-Chem model to study the influence of long-range transport of pollution from the midlatitude northern hemisphere to the remote atmosphere. We are interested in characterizing the pathways for transport of this pollution into the southern hemisphere and the interannual variability of the transport pathways. A particular focus is in on quantifying the impact of Asian pollution on CO and O3 in the remote atmosphere, and understanding how changes in climate over the last 2-3 decades have influenced the export of Asian pollution to the global atmosphere.

3) Analysis of the impact of convective transport of tropospheric pollution on the composition of the upper troposphere and lower stratosphere (UTLS)

Recent modelling and measurement studies have shown that convective transport in the Asian monsoon region can provide a significant source of CO to the lower stratosphere. Correlations between species such as CO and O3 are useful diagnostics of stratosphere-troposphere exchange in the extratropical UTLS. We are using correlations between satellite observations of CO and O3 and assimilated data products to quantify stratosphere-troposphere exchange in the UTLS and to better constrain the influence of pollution from convective regions such as Asia on the composition of the UTLS region.

4) Data assimilation and inverse modelling of atmospheric trace constituents

Recently, inverse modelling has become an important tool in atmospheric science for obtaining “top down” estimates of emissions of trace gases such as, CO2, CO and CH4. In this approach, the mismatch between observations of the trace species and a forward model simulation of the observations is minimized to obtain an optimized estimate of the emissions that best fits the observations, given the uncertainty of the observations and the model. We are exploring ways of optimizing these to more reliably quantify surface fluxes of gases such as atmospheric CO and CO2.