| Summary: | Nitrous oxide (N2O) is a potent greenhouse gas with radiative forcing 265-298 times stronger than that of carbon dioxide (CO2). Increasing atmospheric N2O burden also contributes to stratospheric ozone depletion. Recent field studies show N2O emissions from the Arctic ecosystems have increased due to warming. To date, the emissions across space and time have not been adequately quantified. Here we revised an extant process-based biogeochemistry model, the Terrestrial Ecosystem Model (TEM) to incorporate more detailed processes of soil biogeochemical nitrogen (N) cycle, permafrost thawing effects, and atmospheric N2O uptake in soils. The model is then used to analyze N2O emissions from pan-Arctic terrestrial ecosystems. We find that both regional N2O production and net emissions increased from 1969 to 2019, with production ranging from 1.2 - 1.3 Tg N yr -1 and net emissions from 1.1 - 1.2 Tg N yr-1 considering the permafrost thaw effects. Soil N2O uptake from the atmosphere was 0.1 Tg N yr -1 with a small interannual variability. Atmospheric N deposition significantly increased N2O emission by 31.5 ± 3.1%. Spatially, terrestrial ecosystems act as net sources or sinks ranging from -12 to 700 mg N m-2 yr-1 depending on temperature, precipitation, soil characteristics, and vegetation types in the region.
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