Analysis of atmospheric CH 4 in Canadian Arctic and estimation of the regional CH 4 fluxes

• Published in: Atmospheric Chemistry and Physics
• Main Authors: M. Ishizawa, D. Chan, D. Worthy, E. Chan, F. Vogel, S. Maksyutov
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2019
• Subjects: Physics; QC1-999; Chemistry; QD1-999; Arctic; Inuvik
• Online Access: https://doi.org/10.5194/acp-19-4637-2019; https://doaj.org/article/ab0829f87bf243718477dc591aba7702

The Canadian Arctic (> 60 ∘ N, 60–141 ∘ W) may undergo drastic changes if the Arctic warming trend continues. For methane ( CH 4 ), Arctic reservoirs are large and widespread, and the climate feedbacks from such changes may be potentially substantial. Current bottom-up and top-down estimates of the regional CH 4 flux range widely. This study analyzes the recent observations of atmospheric CH 4 from five arctic monitoring sites and presents estimates of the regional CH 4 fluxes for 2012–2015. The observational data reveal sizeable synoptic summertime enhancements in the atmospheric CH 4 that are distinguishable from background variations, which indicate strong regional fluxes (primarily wetland and biomass burning CH 4 emissions) around Behchoko and Inuvik in the western Canadian Arctic. Three regional Bayesian inversion modelling systems with two Lagrangian particle dispersion models and three meteorological datasets are applied to estimate fluxes for the Canadian Arctic and show relatively robust results in amplitude and temporal variations across different transport models, prior fluxes, and subregion masking. The estimated mean total CH 4 flux for the entire Canadian Arctic is 1.8±0.6 Tg CH 4 yr −1 . The flux estimate is partitioned into biomass burning of 0.3±0.1 Tg CH 4 yr −1 and the remaining natural (wetland) flux of 1.5±0.5 Tg CH 4 yr −1 . The summer natural CH 4 flux estimates clearly show inter-annual variability that is positively correlated with surface temperature anomalies. The results indicate that years with warmer summer conditions result in more wetland CH 4 emissions. More data and analysis are required to statistically characterize the dependence of regional CH 4 fluxes on the climate in the Arctic. These Arctic measurement sites will aid in quantifying the inter-annual variations and long-term trends in CH 4 emissions in the Canadian Arctic.