Characterizing methane flux hotspots over boreal wetlands using surface renewal theory
Abstract
Boreal wetlands emissions largely contribute to the global methane (CH 4 ) budget . In these environments, CH 4 is emitted through three main mechanisms: diffusion, plant-mediated transport , and the localized release o f bubbles. The interplay of these different pathways determine CH 4 fluxes which are highly variable in space and time when compared to other gases such as carbon dioxide and water vapor. For th is reason, characterizing the variability of CH 4 fluxes and the relative contributions of different gas transfer mechanisms in these environments rem a ins a challenging area of research. Here we introduce a framework to partition the CH 4 fluxes based on the spatial homogeneity of the gas source s at the surface when compared to a reference gas such as water vapor. Combining a wavelet partition scheme with the theory of surface renewals, we then characterize strength and intermittency of localized CH 4 "hotspot" sources relative to a background steady emission. We apply and test this approach using a large dataset of turbulent air velocity and multiple scalar concentrations measured over a boreal peatland in southern Finland. This metho do logy applied to an extensive dataset allows us to I) characterize the effects of CH 4 localized hotspots on the gas transport efficiency, and II) analyze the role of possible environmental controls such as water table levels and atmospheric pressure on the measured methane fluxes.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH199.0005Z
- Keywords:
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- 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSES;
- 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 1843 Land/atmosphere interactions;
- HYDROLOGY