FLUXNET-CH4 is an initiative led by the Global Carbon Project, in close partnership with AmeriFlux and EuroFlux, to compile a global database of eddy covariance (EC) methane flux measurements. Data are standardized, post-processed (i.e., partitioned and gap-filled), and released as FLUXNET-CH4. FLUXNET-CH4 Version 1.0 includes data from 81 sites, representing freshwater, coastal, upland, natural, and managed ecosystems. The near continuous, high-frequency nature of EC measurements offers significant promise for improving our understanding of ecosystem-scale CH4 flux dynamics.

The FLUXNET-CH4 Community Product is distributed in files separated by sites and by temporal aggregation resolutions (e.g., half-hourly or daily). Version information is also assigned to the file to document changes required for a site. The file naming convention below details these options for each file. Multiple files with different temporal aggregation resolution (same site, same data product) are available for download as a single ZIP file archive. Site information metadata are also provided with a data download. Data variable descriptions can be found here.

The FLUXNET-CH4 Community Product is distributed under the two tiers of the FLUXNET2015 Data Policy. Tower teams chose data policy tiers for their site. Data distributed in both tiers can be accessed from the Data Download page for the FLUXNET-CH4 Dataset. To see a list of site-years of data available for each site, please refer to the list of sites and data availability.

IMPORTANT: In case of a synthesis using both CC-By-4.0 (Tier One) and Tier Two data, all data should be treated as Tier Two. See the FLUXNET 2015 Data Policy for an explanation of data tiers.

This dataset provides monthly globally gridded freshwater wetland methane emissions from 2001-2018 in nmol CH4 m-2 s-1, g C-CH4 m-2 d-1, and TgCH4 grid cell-1 month-1. The data were derived from a six-predictor random forest upscaling model (UpCH4) trained on 119 site-years of eddy covariance CH4 flux data from 43 freshwater wetland sites covering bog (8), fen (8), marsh (10), swamp (6), and wet tundra (11) wetland classes and distributed across Arctic-boreal (20), temperate (16), and (sub)tropical (7) climate zones. Weekly mean CH4 fluxes were computed from half-hourly FLUXNET-CH4 Version 1.0 fluxes. Each grid cell CH4 flux prediction was weighted by fractional grid cell wetland extent to estimate CH4 emissions using the primary global dataset of Wetland Area and Dynamics for Methane Modeling (WAD2M) product and an alternate Global Inundation Estimate from Multiple Satellites GIEMS version 2 global wetland map. Both WAD2M and GIEMS-2 maps were modified with several correction data layers to represent the monthly area covered by vegetated wetlands, excluding open water and coastal wetlands. The data products are: mean daily fluxes with no adjustment for wetland area (i.e., flux densities assuming hypothetical 100% wetland cover); mean daily fluxes adjusting for WAD2M or GIEMS-2 wetland area; and by-pixel monthly sum of freshwater wetland methane emissions adjusting for WAD2M or GIEMS-2 wetland area. The data are provided in NetCDF4 format.

This dataset contains metadata for methane flux sites in Version 1.0 of FLUXNET-CH4. The dataset also has seasonality parameters for select freshwater wetlands, which were extracted from the raw datasets published at https://fluxnet.org/data/fluxnet-ch4-community-product/. These data are used to analyze global methane flux seasonality patterns in the paper "FLUXNET-CH4: A global, multi-ecosystem dataset and analysis of methane seasonality from freshwater wetlands" by Delwiche et al.

This is the FLUXNET-CH4 version of the carbon flux data for the site DE-Hte Huetelmoor.

This is the FLUXNET-CH4 version of the carbon flux data for the site CH-Cha Chamau.

The dataset used in this study is FLUXNET-CH4, a global network of sites that provides continuous, high-frequency, and quality-checked eddy covariance CH! flux measurements.

Global methane (CH4) emissions have reached approximately 600 Tg per year, 20-40% of which are from wetlands. Of the primary factors affecting these emissions, the water table level is among the most uncertain. Here, a global meta-analysis of chamber and flux-tower observations of CH4 emissions shows that wetlands have maximum emissions at a critical level of inundation.

This record is for the dataset “FLUXNET-CH4 CA-SCC Scotty Creek Landscape” at https://doi.org/10.18140/FLX/1669628 This is the FLUXNET-CH4 version of the carbon flux data for the site CA-SCC Scotty Creek Landscape. Site Description - The Scotty Creek flux tower is located in an organic-rich boreal forest-wetland landscape about 50 km south of Fort Simpson in the Taiga Plains of the Mackenzie watershed. The tower was installed in 2013 and operates an open-path EC system year-round running on solar power only. Flux footprints contain about 50 % forested peat plateaus and 50 % wetlands (i.e., collapse-scar bogs). The forests are underlain by permafrost, while the treeless wetlands are permafrost-free. The tower itself is located on a forested peat plateau. Black spruce tree density on plateaus is sparse and the mean canopy height is ca. 5 m. The dataset can be downloaded at https://doi.org/10.18140/FLX/1669628

This is the FLUXNET-CH4 version of the carbon flux data for the site US-ORv Olentangy River Wetland Research Park.

This record is for the dataset “FLUXNET-CH4 CA-SCB Scotty Creek Bog ” at https://doi.org/10.18140/FLX/1669613 . This is the FLUXNET-CH4 version of the carbon flux data for the site CA-SCB Scotty Creek Bog. Site Description - The Scotty Creek bog flux tower is located in an organic-rich collapse-scar bog about 50 km south of Fort Simpson in the Taiga Plains of the Mackenzie watershed. The tower was installed in 2014 and operates an open-path EC system year-round running on solar power only. The collapse-scar bog is treeless and free of permafrost. This dataset can be downloaded at https://doi.org/10.18140/FLX/1669613

This dataset is a part of the paper "Machine Learning Driven Sensitivity Analysis of E3SM Land Model Parameters for Wetland Methane Emissions", accepted for publication in the Journal of Advances in Modeling Earth Systems (JAMES).

Contents

This dataset includes:

• lhs-gen-190.csv: Training input LHS samples generated by lhsgen.py.
• lhs-gen-50-test.csv: Test input LHS samples generated by lhsgen.py.
• 190-elm-samples.csv: Training input perturbed parameter samples for performing ELM simulations.
• 50-elm-test-samples.csv: Test input perturbed parameter samples for performing ELM simulations.
• train_CH-CHA.csv: Contains the five ELM simulation output flux values for 240 samples (190 train + 50 test).
• lhsgen.py: Script for generating Latin Hypercube Samples.
• gpr-fit-new.py: Script for fitting Gaussian Process Regression (GPR) models.
• sobol-new.py: Script for performing Sobol sensitivity analysis.

Usage

1. lhsgen.py:
   • Use this script to generate the Latin Hypercube Samples for parameter sampling.
2. gpr-fit-new.py:
   • This script fits GPR models using the training samples provided in lhs-gen-190.csv.
   • It tests the models using the input testing samples in lhs-gen-50-test.csv.
   • The fitted GPR models are stored as .joblib files in the gpr_models directory.
   • Corresponding cross-validation and R-squared values are stored in .xlsx files.
3. sobol-new.py:
   • This script performs Sobol sensitivity analysis using the fitted GPR models by reading the .joblib files.
   • The Sobol indices are written to .xlsx files in the results directory.

This is the FLUXNET-CH4 version of the carbon flux data for the site US-StJ St Jones Reserve.

This is the FLUXNET-CH4 version of the carbon flux data for the site US-Tw1 Twitchell Wetland West Pond.

This dataset is used to present the impact of hydrological fluctuations on methane flux dynamics in wetlands. The data, from 31 wetland sites in FLUXNET, include measurements of water table levels, methane fluxes, and relevant environmental variables, which are essential for understanding the methane-related biogeochemical processes in wetlands. The observational data have been made publicly available for transparency and to support further research on wetland methane emissions and their implications for climate change.

Temperature dependence is a crucial parameter in estimating methane (CH4) fluxes from natural wetlands, yet our understanding of this parameter remains inadequate. Seasonal fluctuations in water levels and ecosystem productivity lead to seasonal differences in CH4 production and oxidation. We hypothesized the existence of seasonality in the temperature dependence of CH4 fluxes. To validate this hypothesis, we analyzed the FLUXNET-CH4 dataset to determine the seasonal variation in temperature dependence of CH4 fluxes. We divided the year into six seasons based on air temperature and assessed the temperature dependence for each season using the apparent activation energy calculated by the Boltzmann-Arrhenius equation. Our results showed that temperature dependence showed a unimodal trend with seasons, with the apparent activation energy peaking in early summer (0.60 eV), and reaching its lowest point in late winter (-0.02 eV). This seasonal pattern of temperature dependence was consistent..., , # Seasonality of temperature dependence of methane fluxes from natural wetlands

Data associated with:

Journal Name: Functional Ecology Journal Code: FE Print ISSN: 0269-8463 Online ISSN: 1365-2435

Title: Seasonality of temperature dependence of methane fluxes from natural wetlands

Authors: Li, Jinshuai; Hao, Tianxiang; Chen, Hongyang; Knox, Sara; Yang, Meng; Chen, Zhi; Yu, Guirui

Contact Author: Tianxiang Hao (E-mail: hao_tianxiang@163.com)

Description of files and variables

1. List of variables in sheet 1 of ECdata.xlsx:

• NUM: Data counting
• SITE_ID: Flux Site ID
• CLASS: Wetland category
• DOM_VEG: Vegetation category
• LATITUDE: Site latitude
• LONGITUDE: Site longitude
• YEAR: Measurement year
• MONTH: Measurement month
• DAY: Measurement day
• NUMBER: Data counting at stations within a year
• TA: Air temperature, unit: ℃
• TS: Soil temperature, unit: ℃
• GPP: Gross primary productivity, unit: g/m2/d
• RE: Rcosystem res...,

The Swiss FluxNet Site Davos is a managed subalpine evergreen forest, located on the Seehorn mountain near Davos in the Swiss Alps. The site is dominated by Norway spruce. The tower is owned by the Federal Office for the Environment (FOEN). Ecosystem flux measurements of CO2, H2O (since 1997) as well as CH4 and N2O (since 2016) are performed with the eddy covariance method. In addition to Swiss FluxNet, the site is part of the National Air Pollution Monitoring Network (NABEL), the Long term Forest Ecosystem Research (LWF), the biological drought and growth indicator network (TreeNet) and of ICOS Switzerland (Integrated Carbon Observation System). Since November 2019, the site is an ICOS Class 1 Ecosystem station.

Measurements

• Ecosystem flux measurements of CO2, H2O vapour (since 1997) as well a CH4 and N2O (since 2016) are performed with the eddy-covariance method. This method is based on measurements of trace gas mixing ratios, using infrared gas analyzers (for CO2, H2O vapor) and laser spectrometers (for CH4 and N2O), combined with wind speed and wind direction measurements, using 3D sonic anemometers. To resolve the short-term turbulent fluctuations in the atmosphere, very fast measurements are needed: we measure at 10-20 Hz, i.e., 10-20 times per second. To assess the energy budget of each ecosystem, also radiation sensors and soil climate profiles are installed at the site.
• Sub-canopy eddy fluxes (CO2, H2O, since 2023 also CH4).
• Continuous profile concentration and forest floor flux measurement of CO2, H2O, CH4, N2O.
• Auxiliary micrometeorology and soil climate measurements.

Data availability

Near real-time flux and meteo data uploaded daily to the ICOS Carbon Portal. Processed flux and meteo data are also available from the European Fluxes Database Cluster and part of Fluxnet2015 dataset.

Data policy

ICOS data license: https://www.icos-cp.eu/data-services/about-data-portal/data-license

Detailed site info: https://www.swissfluxnet.ethz.ch/index.php/sites/ch-dav-davos/site-info-ch-dav/

This is the FLUXNET-CH4 version of the carbon flux data for the site CH-Dav Davos.

This is the FLUXNET-CH4 version of the carbon flux data for the site FR-LGt La Guette.

FLUXNET Canada is a Fluxnet research network comprised of the Fluxnet-Canada Research Network (FCRN) and the Canadian Carbon Program (CCP) operating from 1993 through 2014. It was a national research network of university and government scientists studying the influence of climate and disturbance on carbon cycling along an east-west transect of Canadian forest and peat land ecosystems. The data provided are measured and modeled results as obtained from the site investigators. They were not standardized and quality-controlled. Data include: atmospheric carbon dioxide (CO2) and water vapor fluxes and many ancillary meteorological variables; soil CO2 efflux and soil moisture; stable carbon isotopes; site soil and vegetation characteristics, plus documentation and descriptions for the 32 tower sites across 12 flux research stations. The time period is from 1993 - 2014; most reported data for a site does not cover the entire period.

Carbon dioxide flux and meteorological data for the Harvard Forest, MA (1992-95) and BOREAS Northern Study Area, Old Black Spruce (Alberta, Canada; 1994-95) FLUXNET sites are provided as examples of the larger FLUXNET data archive available at the ORNL Distributed Active Archive Center [ http://daac.ornl.gov/FLUXNET/fluxnet.html]. FLUXNET is a global network of micrometeorological tower sites that use eddy covariance methods to measure the exchanges of carbon dioxide (CO2), water vapor, and energy between terrestrial ecosystem and atmosphere.

Gap-filled flux data and meteorological data for half-hourly, daily, weekly, monthly, and annual time intervals are presented for each site and year. There are 6 *.zip files with this data set.