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This work presents an evaluation of modeled atmospheric concentrations of O3, CO and CH4 from eleven models, as presented in the most recent assessment report by the Arctic Monitoring and Assessment Programme (AMAP) on short-lived climate forcers. AMAP is a scientific working group that was created to advise the Arctic Council on matters of Arctic pollution, climate change and the associated threats to local ecosystems and health. This framework is then used to inform policy and decision making through science-based assessments. The current report focuses on the impacts of Short-Lived Climate Forcers (SLCFs) on the Arctic climate, atmospheric chemistry, and human health. The report presents model-measurement comparisons to assess the performance of atmospheric modelling of SLCFs in the Arctic for the years 2008, 2009, 2014 and 2015. The 3-hourly mixing ratios of select SLCFs and related gases are modelled by CESM, CMAM, DEHM, EMEP-MSC-W, GEM-MACH, GEOS-Chem, MATCH, MATCH-SALSA, MRI-ESM2, UKESM1 and WRF-Chem. This presentation will compare these outputs to corresponding trace gas measurements from ground-based Fourier Transform Infrared (FTIR) spectrometers. The FTIR instruments used are part of the Network for the Detection of Atmospheric Composition Change (NDACC) Infrared Working Group, with emphasis on results from the Canadian High Arctic site at the Polar Environment Atmospheric Research Laboratory, in Eureka, Nunavut (80.05ºN, 86.42ºW). Analyses are performed by converting model outputs into smoothed partial columns of O3, CO and CH4, at the locations of the FTIR instruments. Comparisons include seasonal cycle analysis, percent differences and regression analysis.

The Arctic Monitoring and Assessment Programme (AMAP), a working group of the Arctic Council, studies and documents the effects of climate change and pollution on Arctic climate, with the intent of informing policy recommendations. One subject of interest is the impact of Short-Lived Climate Forcers (SLCFs), atmospheric components with lifetimes shorter than that of carbon dioxide; the 2021 AMAP Assessment Report is focused on the climate and health effects of SLCFs in the Arctic and globally. AMAP uses multiple models to determine levels of SLCFs in the Arctic. These models include CESM, CMAM, DEHM, EMEP-MSC-W, GEM-MACH, GEOS-Chem, MATCH, MATCH-SALSA, MRI-ESM2, UKESM1, and WRF-Chem. This work compares outputs from these models for carbon monoxide and, where possible, methane, to data from ground-based Fourier Transform Infrared (FTIR) Spectrometers focused on the near-infrared spectral region. These spectrometers are part of the Total Carbon Column Observing Network (TCCON) and are located in Eureka (Nunavut, Canada), Ny Ålesund (Spitzbergen, Norway), and Sodankylä (Finland). The model outputs are mixing ratios given at three-hour intervals for the years 2009, 2014 and 2015; these are transformed as necessary to be compared to the TCCON column-averaged dry air mole fraction (Xgas) data product. TCCON has been used for many validation studies in the past and these stations in particular provide an essential high Arctic data set with very low site-to-site bias. We will assess the ability of the AMAP models to simulate high Arctic CO and CH4 in order to better understand their suitability to inform SLCF policies.

International audience; The University of Toronto Atmospheric Observatory and Environment Canada's Centre for Atmospheric Research Experiments each has over a decade of ground-based Fourier transform infrared (FTIR) spectroscopy measurements in southern Ontario. We present the Toronto area FTIR time series from 2002 to 2013 of two tropospheric trace gases—ozone and carbon monoxide—along with surface in situ measurements taken by government monitoring programs. We interpret their variability with the GEOS-Chem chemical transport model and determine the atmospheric conditions that cause pollution events in the time series. Our analysis includes a regionally tagged O3 model of the 2004–2007 time period, which quantifies the geographical contributions to Toronto area O3. The important emission types for 15 pollution events are then determined with a high-resolution adjoint model. Toronto O3, during pollution events, is most sensitive to southern Ontario and U.S. fossil fuel NOx emissions and natural isoprene emissions. The sources of Toronto pollution events are found to be highly variable, and this is demonstrated in four case studies representing local, short-, middle-, and long-range transport scenarios. This suggests that continental-scale emission reductions could improve air quality in the Toronto region. We also find that abnormally high temperatures and high-pressure systems are common to all pollution events studied, suggesting that climate change may impact Toronto O3. Finally, we quantitatively compare the sensitivity of the surface and column measurements to anthropogenic NOx emissions and show that they are remarkably similar. This work thus demonstrates the usefulness of FTIR measurements in an urban area to assess air quality.