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  • 1
    Electronic Resource
    Electronic Resource
    Statistics of atmospheric turbulence within a natural black spruce forest canopy (1988)
    Springer
    Boundary layer meteorology 44 (1988), S. 267-283 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Turbulence statistics were measured in a natural black-spruce forest canopy in southeastern Manitoba, Canada. Sonic anemometers were used to measure time series of vertical wind velocity (w), and cup anemometers to measure horizontal wind speed (s), above the canopy and at seven different heights within the canopy. Vertical profiles were measured during 25 runs on eight different days when conditions above the canopy were near-neutral. Profiles of s and of the standard deviation (Σ w ) of w show relatively little scatter and suggest that, for this canopy and these stability conditions, profiles can be predicted from simple measurements made above the canopy. Within the canopy, a negative skewness and a high kurtosis of the w-frequency distributions indicate asymmetry and the persistence of large, high-velocity eddies. The Eulerian time scale is only a weak function of height within the canopy. Although w-power spectra above the canopy are similar to those in the free atmosphere, we did not observe an extensive inertial subrange in the spectra within the canopy. Also, a second peak is present that is especially prominent near the ground. The lack of the inertial subrange is likely caused by the presence of sources and sinks for turbulent kinetic energy within our canopy. The secondary spectral peak is probably generated by wake turbulence caused by form drag on the wide, horizontal spruce branches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00116066
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Drag coefficients and turbulence spectra within three boreal forest canopies (1990)
    Springer
    Boundary layer meteorology 52 (1990), S. 227-246 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Atmospheric turbulence was measured within a black spruce forest, a jack pine forest, and a trembling aspen forest, located in southeastern Manitoba, Canada. Drag coefficients (C d ) varied little with height within the pine and aspen canopies, but showed some height dependence within the dense spruce canopy. A constant C d of 0.15, with the measured momentum flux and velocity profiles, gave good estimates of leaf-area-index (LAI) profiles for the pine and aspen canopies, but underestimated LAI for the spruce canopy. Velocity spectra were scaled using the Eulerian integral time scales and showed a substantial inertial subrange above the canopies. In the bottom part of the canopies, the streamwise and cross-stream spectra showed rapid energy loss whereas the vertical spectra showed an apparent energy gain, in the region where the inertial subrange is expected. The temperature spectra showed an inertial subrange with the expected -2/3 slope at all heights. Cospectra of momentum and heat flux had slopes of about -1 in much of the inertial subrange. Possible mechanisms to explain some of the spectral features are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122088
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Evapotranspiration from a boreal forest drainage basin using an energy balance/eddy correlation technique (1987)
    Springer
    Boundary layer meteorology 38 (1987), S. 125-139 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Meteorological techniques were used to monitor evapotranspiration (ET) at two sites in a boreal forest drainage basin located in southeastern Manitoba, Canada. An energy balance method was used in which net radiation (R N ) and ground heat flux (G) were measured directly. Sensible heat flux (H) was measured by the eddy correlation technique using a propeller anemometer and a fine-wire thermocouple. The energy components were calculated hourly on-line, and data were collected reliably over a five-month period. The R N and H instruments were mounted above the forest canopy and simultaneous measurements of H at heights of 12 and 6 m were in good agreement. Measurements at an open bare rock site indicated that G could be a substantial fraction of the daily RN at some locations, but over longer time periods, it was a small fraction and, therefore, was ignored. The two measurement locations represented upland (open bedrock/jack pine forest) and lowland (aspen/willow forest) sites in the drainage basin. The mean daily value of R N - H at the upland site was 0.57 times the value at the lowland location owing to differences in R N , H, and G. The mean ratio of daily H/R N was 0.6 for the upland site and 0.4 for the lowland site. A basin-wide ET was calculated by weighting the values for the two sites in proportion to their areas. The measured ET agreed well with precipitation minus runoff for the basin. Differences between these two quantities in summer and fall were attributed to water release and storage by the ground, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121560
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of turbulence statistics within three boreal forest canopies (1990)
    Springer
    Boundary layer meteorology 51 (1990), S. 99-121 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three-dimensional sonic anemometers were used to measure velocities and temperatures within three natural boreal forest canopies. Vertical profiles of atmospheric turbulence statistics for a black spruce forest, a jack pine forest, and a trembling aspen forest, all located in southeastern Manitoba, were plotted and compared. The canopy structures were quite different, with total leaf-area indices of 2, 4 and 10, for the pine, aspen, and spruce forests, respectively. The profiles of the first and second moments differed among the canopies, where velocities decreased more rapidly in the top portions of the denser canopies. The velocity distributions were skewed and kurtotic within all canopies, and showed some differences among the canopies. Eulerian time scale profiles were generally similar among the canopies, and the vertical and streamwise time scale profiles were almost mirror images of each other. Eulerian length scale profiles showed some differences among canopies caused by differences in the velocity profiles. Ratios of vertical-to-horizontal time and length scales had a maximum in mid-canopy. Shear stress profiles were similar in the top parts of all canopies, and upward momentum fluxes were occasionally observed within the canopy trunk space. Countergradient heat fluxes were also observed sometimes. The countergradient fluxes and the skewed, kurtotic velocity distributions indicate the contribution of intermittent, large-scale eddies that are important for energy and mass transfer within canopies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00120463
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Frontiers of environmental radioactivity (1999)
    Springer
    Journal of radioanalytical and nuclear chemistry 239 (1999), S. 45-52 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Some frontiers of environmental radioactivity are outlined where radioecologists and chemists are required to solve environmental problems. The first theme is the need for research on biogeochemical cycling of both stable and radioactive nuclides. The second theme discusses measurement challenges in radioecology. The third theme is related to predictive abilities where much of the present radioecology work is aimed at estimates of impacts in the future. These three themes are linked because our predictive abilities of radionuclide transport require a better knowledge of nuclide cycling, and nuclide cycling can only be studied with the availability of good measurement techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02349531
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    Paper (German National Licenses)
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  • 6
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    Author Correction: The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data (2021)
    In:  Scientific Data
    Details
    Publication Date: 2022-02-08
    Description: The following authors were omitted from the original version of this Data Descriptor: Markus Reichstein and Nicolas Vuichard. Both contributed to the code development and N. Vuichard contributed to the processing of the ERA-Interim data downscaling. Furthermore, the contribution of the co-author Frank Tiedemann was re-evaluated relative to the colleague Corinna Rebmann, both working at the same sites, and based on this re-evaluation a substitution in the co-author list is implemented (with Rebmann replacing Tiedemann). Finally, two affiliations were listed incorrectly and are corrected here (entries 190 and 193). The author list and affiliations have been amended to address these omissions in both the HTML and PDF versions. © 2021, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 7
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    The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data (2020)
    In:  Scientific Data
    Details
    Publication Date: 2020-12-14
    Description: 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.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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