The ABCflux database: Arctic–boreal CO₂ flux observations and ancillary information aggregated to monthly time steps across terrestrial ecosystems

Abstract

Abstract. Past efforts to synthesize and quantify the magnitude and change in carbon dioxide (CO2) fluxes in terrestrial ecosystems across the rapidly warming Arctic–boreal zone (ABZ) have provided valuable information but were limited in their geographical and temporal coverage. Furthermore, these efforts have been based on data aggregated over varying time periods, often with only minimal site ancillary data, thus limiting their potential to be used in large-scale carbon budget assessments. To bridge these gaps, we developed a standardized monthly database of Arctic–boreal CO2 fluxes (ABCflux) that aggregates in situ measurements of terrestrial net ecosystem CO2 exchange and its derived partitioned component fluxes: gross primary productivity and ecosystem respiration. The data span from 1989 to 2020 with over 70 supporting variables that describe key site conditions (e.g., vegetation and disturbance type), micrometeorological and environmental measurements (e.g., air and soil temperatures), and flux measurement techniques. Here, we describe these variables, the spatial and temporal distribution of observations, the main strengths and limitations of the database, and the potential research opportunities it enables. In total, ABCflux includes 244 sites and 6309 monthly observations; 136 sites and 2217 monthly observations represent tundra, and 108 sites and 4092 observations represent the boreal biome. The database includes fluxes estimated with chamber (19 % of the monthly observations), snow diffusion (3 %) and eddy covariance (78 %) techniques. The largest number of observations were collected during the climatological summer (June–August; 32 %), and fewer observations were available for autumn (September–October; 25 %), winter (December–February; 18 %), and spring (March–May; 25 %). ABCflux can be used in a wide array of empirical, remote sensing and modeling studies to improve understanding of the regional and temporal variability in CO2 fluxes and to better estimate the terrestrial ABZ CO2 budget. ABCflux is openly and freely available online (Virkkala et al., 2021b, https://doi.org/10.3334/ORNLDAAC/1934).

Sunlight Induces the Production of Atmospheric Volatile Organic Compounds (VOCs) from Thermokarst Ponds

“…The first one is their subsequent oxidation to CO 2 . Since gaseous emission measurements from lakes focus on CO 2 and CH 4 , ,− neglecting this delayed CO 2 source may underestimate the greenhouse gas (GHG) emissions by lakes. Both field and laboratory studies indicate that incomplete photooxidation may represent up to half the photolysis products in lakes. , The second one is through the formation of ozone (O 3 ), a potent GHG, as many of the reactive organic compounds emitted are likely to have a strong O 3 formation potential .…”

Landscape‐variability of the carbon balance across managed boreal forests

“…A key limitation to these ambitions is that the boreal forest C cycle has remained understudied relative to other, e.g., temperate regions (Luyssaert et al, 2007 ; Xu et al, 2014 ). Moreover, there is a bias toward studies in boreal Canada and Russia, where the boreal forest succession is often driven by natural disturbance regimes, such as wildfires, insect outbreaks and wind throws (Amiro et al, 2010 ; Bond‐Lamberty et al, 2004 ; Virkkala et al, 2022 ). In comparison, our knowledge on the magnitudes and variations of the forest C balance of actively managed landscapes occurring within the boreal regions of Fennoscandia is limited (Bellassen & Luyssaert, 2014 ).…”

Widespread deepening of the active layer in northern permafrost regions from 2003 to 2020

“…We collected in-situ ALT measurement data from four different sources between 2003 and 2020, totaling 2966 site-years, including the Circumpolar Active Layer Monitoring Network (CALM, 2409 site-years; (Brown et al 2000, Nelson et al 2021, NASA Arctic Boreal Vulnerability Experiment (ABoVE) Soil Moisture and Active Layer Thickness (SMALT) data (257 site-years; (Clayton et al 2021), Arctic-boreal CO 2 flux (ABCflux) Database (142 site-years; (Virkkala et al 2022), and additional ALT measurements from the Tibetan Plateau (158 site-years; figure 1) (Zhao et al 2021, Wu et al 2022.…”