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1. Quantifying Water and Energy Fluxes Over Different Urban Land Covers in Phoenix, Arizona: Water and Energy Fluxes Over Urban Cover

   https://doi.org/10.1002/2017JD027845  

   Templeton, Nicole P.; Vivoni, Enrique R.; Wang, Zhi-Hua; Schreiner-McGraw, Adam P. (February 2018, Journal of Geophysical Research: Atmospheres)
2. Gap-filling carbon dioxide, water, energy, and methane fluxes in challenging ecosystems: Comparing between methods, drivers, and gap-lengths

   https://doi.org/10.1016/j.agrformet.2023.109365  

   Zhu, Songyan; McCalmont, Jon; Cardenas, Laura M; Cunliffe, Andrew M; Olde, Louise; Signori-Müller, Caroline; Litvak, Marcy E; Hill, Timothy (April 2023, Agricultural and Forest Meteorology)

   Eddy covariance serves as one the most effective techniques for long-term monitoring of ecosystem fluxes, however long-term data integrations rely on complete timeseries, meaning that any gaps due to missing data must be reliably filled. To date, many gap-filling approaches have been proposed and extensively evaluated for mature and/or less actively managed ecosystems. Random forest regression (RFR) has been shown to be stable and perform better in these systems than alternative approaches, particularly when filling longer gaps. However, the performance of RFR gap filling remains less certain in more challenging ecosystems, e.g., actively managed agri-ecosystems and following recent land-use change due to management disturbances, ecosystems with relatively low fluxes due to low signal to noise ratios, or for trace gases other than carbon dioxide (e.g., methane). In an extension to earlier work on gap filling global carbon dioxide, water, and energy fluxes, we assess the RFR approach for gap filling methane fluxes globally. We then investigate a range of gap-filling methodologies for carbon dioxide, water, energy, and methane fluxes in challenging ecosystems, including European managed pastures, Southeast Asian converted peatlands, and North American drylands. Our findings indicate that RFR is a competent alternative to existing research standard gap-filling algorithms. The marginal distribution sampling (MDS) is still suggested for filling short (< 12 days) gaps in carbon dioxide fluxes, but RFR is better for filling longer (> 30 days) gaps in carbon dioxide fluxes and also for gap filling other fluxes (e.g. sensible heat, latent energy and methane). In addition, using RFR with globally available reanalysis environmental drivers is effective when measured drivers are unavailable. Crucially, RFR was able to reliably fill cumulative fluxes for gaps > 3 moths and, unlike other common approaches, key environment-flux responses were preserved in the gap-filled data. 

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3. Coupling carbon and energy fluxes in the North Pacific Subtropical Gyre

   https://doi.org/10.1038/s41467-019-09772-z  

   Grabowski, Eric; Letelier, Ricardo M.; Laws, Edward A.; Karl, David M. (December 2019, Nature Communications)
4. Resolving the Carbon‐Climate Feedback Potential of Wetland CO ₂ and CH ₄ Fluxes in Alaska

   https://doi.org/10.1029/2022GB007524  

   Ma, Shuang; Bloom, A. Anthony; Watts, Jennifer D.; Quetin, Gregory R.; Donatella, Zona; Euskirchen, Eugénie S.; Norton, Alexander J.; Yin, Yi; Levine, Paul A.; Braghiere, Renato K.; et al (September 2023, Global Biogeochemical Cycles)

   Abstract Boreal‐Arctic regions are key stores of organic carbon (C) and play a major role in the greenhouse gas balance of high‐latitude ecosystems. The carbon‐climate (C‐climate) feedback potential of northern high‐latitude ecosystems remains poorly understood due to uncertainty in temperature and precipitation controls on carbon dioxide (CO₂) uptake and the decomposition of soil C into CO₂and methane (CH₄) fluxes. While CH₄fluxes account for a smaller component of the C balance, the climatic impact of CH₄outweighs CO₂(28–34 times larger global warming potential on a 100‐year scale), highlighting the need to jointly resolve the climatic sensitivities of both CO₂and CH₄. Here, we jointly constrain a terrestrial biosphere model with in situ CO₂and CH₄flux observations at seven eddy covariance sites using a data‐model integration approach to resolve the integrated environmental controls on land‐atmosphere CO₂and CH₄exchanges in Alaska. Based on the combined CO₂and CH₄flux responses to climate variables, we find that 1970‐present climate trends will induce positive C‐climate feedback at all tundra sites, and negative C‐climate feedback at the boreal and shrub fen sites. The positive C‐climate feedback at the tundra sites is predominantly driven by increased CH₄emissions while the negative C‐climate feedback at the boreal site is predominantly driven by increased CO₂uptake (80% from decreased heterotrophic respiration, and 20% from increased photosynthesis). Our study demonstrates the need for joint observational constraints on CO₂and CH₄biogeochemical processes—and their associated climatic sensitivities—for resolving the sign and magnitude of high‐latitude ecosystem C‐climate feedback in the coming decades. 

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5. Dominant role of soil moisture in mediating carbon and water fluxes in dryland ecosystems

   https://doi.org/10.1038/s41561-023-01351-8  

   Kannenberg, Steven A.; Anderegg, William R.; Barnes, Mallory L.; Dannenberg, Matthew P.; Knapp, Alan K. (January 2024, Nature Geoscience)