Detecting Hot Spots of Methane Flux Using Footprint-Weighted Flux Maps

Camilo Rey-Sanchez*, Ariane Arias-Ortiz, Kuno Kasak, Housen Chu, Daphne Szutu, Joseph Verfaillie, Dennis Baldocchi

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

13 Citations (Scopus)

Abstract

In this study, we propose a new technique for mapping the spatial heterogeneity in gas exchange around flux towers using flux footprint modeling and focusing on detecting hot spots of methane (CH4) flux. In the first part of the study, we used a CH4 release experiment to evaluate three common flux footprint models: the Hsieh model (Hsieh et al., 2000), the Kljun model (Kljun et al., 2015), and the K & M model (Kormann and Meixner, 2001), finding that the K & M model was the most accurate under these conditions. In the second part of the study, we introduce the Footprint-Weighted Flux Map, a new technique to map spatial heterogeneity in fluxes. Using artificial CH4 release experiments, natural tracer approaches and flux chambers we mapped the spatial flux heterogeneity, and detected and validated a hot spot of CH4 flux in a oligohaline restored marsh. Through chamber measurements during the months of April and May, we found that fluxes at the hot spot were on average as high as 6589 ± 7889 nmol m−2 s−1 whereas background flux from the open water were on average 15.2 ± 7.5 nmol m−2 s−1. This study provides a novel tool to evaluate the spatial heterogeneity of fluxes around eddy-covariance towers and creates important insights for the interpretation of hot spots of CH4 flux, paving the way for future studies aiming to understand subsurface biogeochemical processes and the microbiological conditions that lead to the occurrence of hot spots and hot moments of CH4 flux.

Original languageEnglish
Article numbere2022JG006977
Number of pages22
JournalJournal of Geophysical Research: Biogeosciences
Volume127
Issue number8
DOIs
Publication statusPublished - Aug 2022

Keywords

  • chambers
  • eddy covariance
  • flux footprint
  • hot spots
  • methane
  • wetlands

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