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

Ishizawa, Misa; Chan, Douglas; Worthy, Doug; Chan, Elton; Vogel, Felix; Maksyutov, Shamil

The Canadian Arctic (> 60inline-formula N, 60–141inline-formula W) may undergo drastic changes if the Arctic warming trend continues. For methane (inline-formulaCH4), 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 inline-formulaCH4 flux range widely. This study analyzes the recent observations of atmospheric inline-formulaCH4 from five arctic monitoring sites and presents estimates of the regional inline-formulaCH4 fluxes for 2012–2015. The observational data reveal sizeable synoptic summertime enhancements in the atmospheric inline-formulaCH4 that are distinguishable from background variations, which indicate strong regional fluxes (primarily wetland and biomass burning inline-formulaCH4 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 inline-formulaCH4 flux for the entire Canadian Arctic is inline-formula1.8±0.6 Tg inline-formulaCH4 yrinline-formula−1. The flux estimate is partitioned into biomass burning of inline-formula0.3±0.1 Tg inline-formulaCH4 yrinline-formula−1 and the remaining natural (wetland) flux of inline-formula1.5±0.5 Tg inline-formulaCH4 yrinline-formula−1. The summer natural inline-formulaCH4 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 inline-formulaCH4 emissions. More data and analysis are required to statistically characterize the dependence of regional inline-formulaCH4 fluxes on the climate in the Arctic. These Arctic measurement sites will aid in quantifying the inter-annual variations and long-term trends in inline-formulaCH4 emissions in the Canadian Arctic.

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Ishizawa, Misa / Chan, Douglas / Worthy, Doug / et al: Analysis of atmospheric CH4 in Canadian Arctic and estimation of the regional CH4 fluxes. 2019. Copernicus Publications.

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