Evidence for El Niño–Southern Oscillation (ENSO) influence on Arctic CO interannual variability through biomass burning emissions

A global chemical transport model is used in conjunction with measurements from surface stations to study the importance of biomass burning and meteorology in driving Arctic carbon monoxide (CO) interannual variability (IAV). Simulations with yearly varying fire emissions capture 66%–93% of CO IAV and a simulation with yearly varying meteorology but fixed fire emissions captures 0–25%, showing that biomass burning variability is the dominant driver of surface CO IAV. Observed CO anomalies are found to be significantly correlated with El Niño (0.58 < r < 0.64, 99% confidence level (CL)) and results indicate that this is due to ENSO's influence on fire emissions. Boreal Alaska, Canada and north‐east Siberia are found to contribute 59% to total Arctic fire CO and 67% to Arctic fire CO IAV. Analysis of meteorological fire drivers in these regions suggests that ENSO affects winter/spring precipitation, driving the Arctic/ENSO relationship.