The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data.

The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.

Thermal comfort in Quebec City, Canada: sensitivity analysis of the UTCI and other popular thermal comfort indices in a mid-latitude continental city.

The newly developed Universal Thermal Climate Index (UTCI), along with the physiological equivalent temperature (PET), the humidex (HX) and the wind chill index (WC), was calculated in Quebec City, Canada, a city with a strong seasonal climatic variability, over a 1-year period. The objective of this study is twofold: evaluate the operational benefits of implementing the UTCI for a climate monitoring program of public comfort and health awareness as opposed to relying on traditional and simple indices, and determine whether thermal comfort monitoring specific to dense urban neighborhoods is necessary to adequately fulfill the goals of the program. In order to do so, an analysis is performed to evaluate each of these indices' sensitivity to the meteorological variables that regulate them in different environments. Overall, the UTCI was found to be slightly more sensitive to mean radiant temperature, moderately more sensitive to humidity and much more sensitive to wind speed than the PET. This dynamic changed slightly depending on the environment and the season. In hot weather, the PET was found to be more sensitive to mean radiant temperature and therefore reached high values that could potentially be hazardous more frequently than the UTCI and the HX. In turn, the UTCI's stronger sensitivity to wind speed makes it a superior index to identify potentially hazardous weather in winter compared to the PET and the WC. Adopting the UTCI broadly would be an improvement over the traditionally popular HX and WC indices. The urban environment produced favorable conditions to sustain heat stress conditions, where the indices reached high values more frequently there than in suburban locations, which advocates for weather monitoring specific to denser urban areas.

Component respiration, ecosystem respiration and net primary production of a mature black spruce forest in northern Quebec.

We measured respiratory fluxes of carbon dioxide by aboveground tree components and soil respiration with chambers in 2005 and scaled up these measurements over space and time to estimate annual ecosystem respiration (R(e)) at a mature black spruce (Picea mariana (Mill.) B.S.P.) ecosystem in Quebec, Canada. We estimated periodic annual net primary production (NPP) for this ecosystem also. R(e) was estimated at 10.32 Mg C ha(-)(1) year(-)(1); heterotrophic respiration (R(h)) accounted for 52% of R(e) and autotrophic respiration (R(a)) accounted for the remainder. We estimated NPP at 3.02 Mg C ha(-1) year(-1), including production of bryophyte biomass but not including shrub NPP. We used these estimates of carbon fluxes to calculate a carbon use efficiency [CUE = NPP/(NPP + R(a))] of 0.38. This estimate of CUE is similar to those reported for other boreal forest ecosystems and it is lower than the value frequently used in global studies. Based on the estimate of R(h) being greater than the estimate of NPP, the ecosystem was determined to emit approximately 2.38 Mg C ha(-1) year(-1) to the atmosphere in 2005. Estimates of gross primary production (GPP = NPP + R(a)) and R(e) differed substantially from estimates of these fluxes derived from eddy covariance measurements during 2005 at this site. The ecological estimates of GPP and R(e) were substantially greater than those estimated for eddy covariance measurements. Applying a correction for lack of energy balance closure to eddy covariance estimates reduces differences with ecological estimates. We reviewed possible sources of systematic error in ecological estimates and discuss other possible explanations for these discrepancies.