Energiebilanzschließung bei Eddy-Kovarianz-Messungen unter Berücksichtigung atmosphärischer Stabilität und thermischer Oberflächenheterogenität

2021 ◽  
Author(s):  
Luise Wanner ◽  
Marc Calaf ◽  
Sreenath Paleri ◽  
Brian Butterworth ◽  
Ankur Desai ◽  
...  
Keyword(s):  
Energy Balance ◽  
High Density ◽  
Balance Study ◽  
Large Eddy

<p>Die Energiebilanzlücke, die durch die Unterschätzung latenter und fühlbarer Wärmeströme in Eddy-Kovarianz-Messungen entsteht, ist ein seit Jahrzehnten bekanntes Problem. Seither wurden verschiedene Ansätze zur Schließung der Lücke entwickelt, die zu einer Verbesserung der Instrumentierung und der Anwendung verschiedener Korrekturmethoden in der Datenaufbereitung geführt haben. Diese Maßnahmen führten bisher jedoch noch nicht zu einer vollständigen Schließung der Energiebilanzlücke. Ein wesentlicher Grund dafür ist, dass der Energietransport durch sub-mesoskalige atmosphärische Zirkulationen definitionsgemäß nicht durch Eddy-Kovarianz-Messungen mit typischen Mittelungszeiten erfasst werden kann. Es gibt bereits einige Ansätze, die verbleibende Lücke zu schließen, indem der fehlende Anteil in unterschiedlichen Verhältnissen den gemessenen fühlbaren und latenten Wärmeflüssen zugerechnet wird. Allerdings gibt es nur wenige Ansätze, die diesen fehlenden Anteil auf der Grundlage kausaler Faktoren bestimmen. Als wichtiger Faktor wurde neben der atmosphärischen Stabilität die Heterogenität der Landschaft, insbesondere die thermische Ungleichmäßigkeit, identifiziert. In einer idealisierten Large-Eddy-Simulationsstudie wurde daher ein neues Modell der Energiebilanzlücke in Abhängigkeit eines atmosphärischen Stabilitätsparameters und eines Heterogenitätsparameters, der sowohl die Amplitude der Oberflächentemperatur als auch die vorherrschende Heterogenitätsskala berücksichtigt, entwickelt. Dieses Modell kann mit nur wenigen zusätzlichen Messungen zur Korrektur von Eddy-Kovarianz-Messungen unter instabilen und konvektiven atmosphärischen Bedingungen in Landschaften unterschiedlicher Oberflächenheterogenität verwendet werden. Das Modell wurde an 17 Eddy-Kovarianz-Stationen, die im Sommer und Herbst 2019 über einen Zeitraum von drei Monaten im Rahmen der umfassenden CHEESEHEAD19 (Chequamegon Heterogeneous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors) Messkampagne im Norden Wisconsins (USA) betrieben wurden, getestet. Wir stellen das neue Modell und dessen Anwendung auf Feldmessungen vor.</p>

Optimizing large-eddy simulations for investigating the energy-balance closure problem at typical flux measurement heights

2020 ◽  
Author(s):  
Luise Wanner ◽  
Frederik De Roo ◽  
Matthias Mauder
Keyword(s):  
Energy Balance ◽  
Eddy Covariance ◽  
Surface Fluxes ◽  
Heat Fluxes ◽  
Large Eddy Simulations ◽  
Scale Model ◽  
Energy Balance Closure ◽  
Balance Study ◽  
Large Eddy ◽  
Secondary Circulations

<p>The eddy-covariance method generally underestimates sensible and latent heat fluxes, resulting in an energy-balance gap from 10 % to even 30 % across sites worldwide. In contrast to single-tower eddy-covariance measurements, large-eddy simulations (LES) provide information on a 3D array of grid points and can capture atmospheric processes such as secondary circulations on all relevant scales, which makes them a powerful tool to investigate this problem. In order to compare LES results to field measurements at 20 m height from the CHEESEHEAD (Chequamegon Heterogeneous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors) campaign, a LES-setup that provides comparability to the measurements at these low levels is necessary. However, former LES studies have shown that the energy balance is almost closed near the surface, which does not reflect the energy-balance gap in measurements. One possible reason might be the common use of prescribed surface fluxes that cannot adapt to changes in surface temperature and moisture, which would allow for the self-reinforcement of secondary circulations. Therefore, we set up an idealized study, in which we compare the performance of the land-surface and plant-canopy models implemented in PALM to the use of prescribed surface fluxes above homogeneous forest and grassland ecosystems under different atmospheric conditions with respect to realistic energy-balance closure behavior. Furthermore, we evaluate the performance of a dynamic subgrid-scale model, as well as an alternative to the Monin-Obukhov similarity theory (Banerjee et al. 2015, Q. J. R. Met. Soc.).</p>

scholarly journals Energy Balance Study of Combined Carbonization and Liquefaction of Coconut Shell

2018 ◽  
Vol 7 (09) ◽  
pp. 2238-2247
Author(s):  
Joshi Priyanka Suhas ◽  
Khot Samreen Anwarali ◽  
A.G. Mohod ◽  
Y.P. Khandetod
Keyword(s):  
Energy Balance ◽  
Coconut Shell ◽  
Balance Study

On the way to realistic large eddy simulations – A comparison of virtual measurements with CHEESEHEAD19 field measurements

2021 ◽  
Author(s):  
Luise Wanner ◽  
Sreenath Paleri ◽  
Johannes Speidel ◽  
Ankur Desai ◽  
Matthias Sühring ◽  
...  
Keyword(s):  
Energy Balance ◽  
Eddy Covariance ◽  
Field Measurements ◽  
Transport Processes ◽  
Large Eddy Simulations ◽  
Surface Model ◽  
Closure Problem ◽  
Energy Balance Closure ◽  
Large Eddy ◽  
Eddy Covariance Measurements

<p>Large-eddy simulations are useful tools to study transport processes by mesoscale structures in the atmospheric boundary layer, since in contrast to single-tower eddy covariance measurements, they provide not only temporally but also spatially highly resolved information. Therefore, they are well suited to study the energy balance closure problem, for which the mesoscale transport of latent and sensible heat, triggered by heterogeneous ecosystems, is suspected to be a major cause. However, this requires simulations that are as realistic as possible and thus allow a comparison of real measurements in the field and virtual measurements in the simulation.<br>During the Chequamegon Heterogeneous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors (CHEESEHEAD) experiment in the summer of 2019, a heterogeneous 10x10 square km domain was intensively sampled across scales. This data offers a unique possibility to set up large-eddy simulations with realistic surface heterogeneity. We use PALM to simulate two days and an area of 40 by 40 square kilometers incorporating the CHEESEHEAD site. The large scale atmospheric forcings to inform the boundary conditions are determined from the NCEP HRRR product. As the lower boundary condition, we use a soil and land-surface model coupled with a plant-canopy model, which we adapt to the CHEESEHEAD area based on ground-based and airborne measurements of plant physiological data.<br>In this study, we investigate how well the simulations match with real measurements by comparing simulated profiles and virtual tower measurements with field measurements from radiosonde ascents, lidar measurements of three-dimensional wind and water vapor, eddy-covariance measurements from the 400 meter tower in the center of the study domain, as well as from typical eddy-covariance stations distributed through the study area. This way, we investigate how realistic the simulations actually are and to what extent the knowledge gained from them concerning the energy balance closure problem can be transferred to field measurements.</p>

scholarly journals HERschel Observations of Edge-on Spirals (HEROES)

2018 ◽  
Vol 616 ◽  
pp. A120 ◽  
Author(s):  
Aleksandr V. Mosenkov ◽  
Flor Allaert ◽  
Maarten Baes ◽  
Simone Bianchi ◽  
Peter Camps ◽  
...  
Keyword(s):  
Energy Balance ◽  
Near Infrared ◽  
Complex Geometry ◽  
Dust Emission ◽  
Three Dimensional ◽  
Stellar Model ◽  
Small Scale ◽  
Balance Study ◽  
Balance Problem ◽  
Double Exponential

We present results of the detailed dust energy balance study for the seven large edge-on galaxies in the HEROES sample using three-dimensional (3D) radiative transfer (RT) modelling. Based on available optical and near-infrared (NIR) observations of the HEROES galaxies, we derive the 3D distribution of stars and dust in these galaxies. For the sake of uniformity, we apply the same technique to retrieve galaxy properties for the entire sample: we use a stellar model consisting of a Sérsic bulge and three double-exponential discs (a superthin disc for a young stellar population and thin and thick discs for old populations). For the dust component, we adopt a double-exponential disc with the new THEMIS dust-grain model. We fit oligochromatic RT models to the optical and NIR images with the fitting algorithm FITSKIRT and run panchromatic simulations with the SKIRT code at wavelengths ranging from ultraviolet to submillimeter. We confirm the previously stated dust energy balance problem in galaxies: for the HEROES galaxies, the dust emission derived from our RT calculations underestimates the real observations by a factor 1.5–4 for all galaxies except NGC 973 and NGC 5907 (apparently, the latter galaxy has a more complex geometry than we used). The comparison between our RT simulations and the observations at mid-infrared–submillimetre wavelengths shows that most of our galaxies exhibit complex dust morphologies (possible spiral arms, star-forming regions, more extended dust structure in the radial and vertical directions). We suggest that, in agreement with results from the literature, the large- and small-scale structure is the most probable explanation for the dust energy balance problem.

The Energy Balance Study: The Design and Baseline Results for a Longitudinal Study of Energy Balance

2013 ◽  
Vol 84 (3) ◽  
pp. 275-286 ◽  
Author(s):  
Gregory A. Hand ◽  
Robin P. Shook ◽  
Amanda E. Paluch ◽  
Meghan Baruth ◽  
E. Patrick Crowley ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Energy Balance ◽  
Balance Study

Use of doubly labeled water technique in soldiers training for jungle warfare

1989 ◽  
Vol 67 (1) ◽  
pp. 14-18 ◽  
Author(s):  
C. H. Forbes-Ewan ◽  
B. L. Morrissey ◽  
G. C. Gregg ◽  
D. R. Waters
Keyword(s):  
Energy Balance ◽  
Food Intake ◽  
Energy Expenditure ◽  
Daily Intake ◽  
Doubly Labeled Water ◽  
Daily Energy Expenditure ◽  
Balance Study ◽  
Wide Range ◽  
Daily Energy ◽  
Doubly Labeled Water Method

The doubly labeled water method was used to estimate the energy expended by four members of an Australian Army platoon (34 soldiers) engaged in training for jungle warfare. Each subject received an oral isotope dose sufficient to raise isotope levels by 200–250 (18O) and 100–120 ppm (2H). The experimental period was 7 days. Concurrently, a factorial estimate of the energy expenditure of the platoon was conducted. Also, a food intake-energy balance study was conducted for the platoon. Mean daily energy expenditure by the doubly labeled water method was 4,750 kcal (range 4,152–5,394 kcal). The factorial estimate of mean daily energy expenditure was 4,535 kcal. Because of inherent inaccuracies in the food intake-energy balance technique, we were able to conclude only that energy expenditure, as measured by this method, was greater than the estimated mean daily intake of 4,040 kcal. The doubly labeled water technique was well tolerated, is noninvasive, and appears to be suitable in a wide range of field applications.

scholarly journals Dust energy balance study of two edge-on spiral galaxies in the Herschel-ATLAS survey

2015 ◽  
Vol 451 (2) ◽  
pp. 1728-1739 ◽  
Author(s):  
Gert De Geyter ◽  
Maarten Baes ◽  
Ilse De Looze ◽  
George J. Bendo ◽  
Nathan Bourne ◽  
...  
Keyword(s):  
Energy Balance ◽  
Spiral Galaxies ◽  
Balance Study
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