| Summary: | Overview- This project proposes to create a long-term, year-round field observations to better understand the controls on greenhouse gas (GHG) emissions from the Arctic at time scales that will encompass significant climate change and variability. Research over decadal time frames is critical for understanding the effect of climate variability and change on carbon dioxide (CO2) and methane (CH4) fluxes and to provide the baseline needed to evaluate temporal changes. This is particularly relevant in arctic ecosystems where the large spatial heterogeneity prevents using nearby stations to build a time series in the GHG emissions, given that fluxes can vary substantially over the meter scale. This project will allow creating the longest running year-round Arctic eddy covariance network, and to standardize, upgrade, and apply the network to improve understanding of the long-term effects of climate variability and change on trace gas feedbacks from the Arctic. This project will make existing data more useful and relevant and will expand an already large user base. A special emphasis will be on the fall zero curtain period when an unfrozen soil layer hovers around 0°Celsius (C) supporting significant CO2 and CH4 releases to the atmosphere, and the entire cold season (Zona et al., 2016). Zero curtain processes plausibly explain how upland tundra can be a larger emitter of CH4 than low-lying, wet tundra, and how the cold seasons might emit more CH4 than the summer season (Zona et al., 2016, Commane et al., 2017). At present, however, cold season observations are too short to adequately test hypotheses concerning the controlling mechanisms or to develop understanding that allows us to predict, with confidence, future CO2 and CH4 fluxes form the Arctic. Five Arctic eddy covariance flux towers will be used to evaluate the long term changes in the CO2 and CH4 fluxes across three moisture environments in Barrow (recently renamed as Utqiaġvik) (CMDL (Climate Monitoring and Diagnostics Laboratory), BEO (Barrow Environmental Observatory), and BES (Biocomplexity Experiment South) towers) and a ~300km latitudinal gradient passing through Atqasuk (ATQ) and culminating in Ivotuk (IVO). These measurements are intended to be of sufficient duration and breadth to capture and interpret the effect of extreme and/or unexpected events on GHG fluxes in the Arctic. The support from this grant would allow expansion of the time series to a more than 20-year record of CO2 and 11-year record of CH4 fluxes, resulting in an unprecedented dataset, critical to refining our analytical and predictive ability of the controls of CH4 loss from the Arctic.
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