Evaluation of large-eddy simulations forced with mesoscale model output for a multi-week period during a measurement campaign

Heinze, Rieke; Moseley, Christopher; Böske, Lennart Nils; Muppa, Shravan Kumar; Maurer, Vera; Raasch, Siegfried; Stevens, Björn

doi:10.5194/acp-17-7083-2017

Cited by 50 publications

(76 citation statements)

References 90 publications

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“…The simulations revealed similar results to the ones obtained with two other large-eddy models (LEMs), the University of California, Los Angeles, Large-Eddy Simulation (UCLA-LES) model and the Parallelized Large-Eddy Simulation Model (PALM; Maronga et al 2015). Furthermore, in the context of the HD(CP) 2 project, the modeling framework employing both ICON-LEM and TERRA-ML has been validated using a semi-idealized approach (Heinze et al 2017a) and by performing real-case simulations (Heinze et al 2017b). In the latter case, the ICON-LEM simulations compare well to simulations performed with the COSMO model, with ICON-LEM in particular producing more realistic mesoscale variability.…”

Section: A the Modeling Frameworksupporting

confidence: 62%

Effect of Soil Moisture on Diurnal Convection and Precipitation in Large-Eddy Simulations

Hohenegger

2017

Journal of Hydrometeorology

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A determination of the sign and magnitude of the soil moisture-precipitation feedback relies either on observations, where synoptic variability is difficult to isolate, or on model simulations, which suffer from biases mainly related to poorly resolved convection. In this study, a large-eddy simulation model with a resolution of 250 m is coupled to a land surface model and several idealized experiments mimicking the full diurnal cycle of convection are performed, starting from different spatially homogeneous soil moisture conditions. The goal is to determine under which conditions drier soils may produce more precipitation than wetter ones. The methodology of previous conceptual studies that have quantified the likelihood of convection to be triggered over wet or dry soils is followed but includes the production of precipitation. Although convection can be triggered earlier over dry soils than over wet soils under certain atmospheric conditions, total precipitation is found to always decrease over dry soils. By splitting the total precipitation into its magnitude and duration component, it is found that the magnitude strongly correlates with surface latent heat flux, hence implying a wet soil advantage. Because of this strong scaling, changes in precipitation duration caused by differences in convection triggering are not able to overcompensate for the lack of evaporation over dry soils. These results are further validated using two additional atmospheric soundings and a series of perturbed experiments that consider cloud radiative effects, as well as the effect of large-scale forcing, winds, and plants on the soil moisture-precipitation coupling.

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Section: A the Modeling Frameworksupporting

confidence: 62%

Effect of Soil Moisture on Diurnal Convection and Precipitation in Large-Eddy Simulations

Hohenegger

2017

Journal of Hydrometeorology

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“…The extension of the model equations to include timedependent forcing is based on Heinze et al (2017) with an extension to include large-scale advection of momentum. The modified equation of motion before applying any approximations is…”

Section: Model Equationsmentioning

confidence: 99%

“…Term 5 defines a large-scale pressure gradient by prescribing a horizontal geostrophic wind speed u g . Term 6 prescribes a large-scale sink or source of momentum and term 7 is a time relaxation of the momentum towards a large-scale state (Neggers et al, 2012;Heinze et al, 2017). The momentum relaxation has no physical justification but is used to prevent a drift of the model from the large-scale state.…”

Section: Model Equationsmentioning

confidence: 99%

“…Following Heinze et al (2017) three-dimensional and surface data are averaged over a horizontal averaging domain of multiple grid points. The nearest grid cell to the FINO1 coordinates is chosen as the center of the averaging domain.…”

Section: Input Data From Cosmo-dementioning

confidence: 99%

“…Recently, long-term LESs of multiple days up to 1 year have been run with this approach to study the changes of meteorological conditions at a measurement site (Neggers et al, 2012;Schalkwijk et al, 2015;Heinze et al, 2017). In the context of wind energy, the approach had only been used in Vollmer et al (2015), in which the measurement and simulation setup of this paper was briefly introduced.…”

Section: Introductionmentioning

confidence: 99%

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Transient LES of an offshore wind turbine

2017

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Abstract. The estimation of the cost of energy of offshore wind farms has a high uncertainty, which is partly due to the lacking accuracy of information on wind conditions and wake losses inside of the farm. Wake models that aim to reduce the uncertainty by modeling the wake interaction of turbines for various wind conditions need to be validated with measurement data before they can be considered as a reliable estimator. In this paper a methodology that enables a direct comparison of modeled with measured flow data is evaluated. To create the simulation data, a model chain including a mesoscale model, a large-eddy-simulation (LES) model and a wind turbine model is used. Different setups are compared to assess the capability of the method to reproduce the wind conditions at the hub height of current offshore wind turbines. The 2-day-long simulation of the ambient wind conditions and the wake simulation generally show good agreements with data from a met mast and lidar measurements, respectively. Wind fluctuations due to boundary layer turbulence and synoptic-scale motions are resolved with a lower representation of mesoscale fluctuations. Advanced metrics to describe the wake shape and development are derived from simulations and measurements but a quantitative comparison proves to be difficult due to the scarcity and the low sampling rate of the available measurement data. Due to the implementation of changing synoptic wind conditions in the LES, the methodology could also be beneficial for case studies of wind farm performance or wind farm control.

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Using observational mean‐flow data to drive large‐eddy simulations of a diurnal cycle at the SWiFT site

2023

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Reproducing realistic date-and site-specific unsteady wind conditions in large-eddy simulations is becoming increasingly useful in wind energy. How to run a large-eddy simulation to match observed conditions, however, remains an open research question. One approach that has received considerable attention is mesoscale-tomicroscale coupling, in which information about the mesoscale weather, most commonly acquired from a mesoscale numerical weather model, is passed on to a microscale model. In this paper, we demonstrate how the recently developed profileassimilation technique, a form of mesoscale-to-microscale coupling, can be used to drive large-eddy simulations solely based on observed mean-flow profiles at a single location, bypassing the need for auxiliary mesoscale simulations. The new approach is evaluated for a diurnal cycle at the Scaled Wind Farm Technology site. Observed mean-flow profiles from the ground up to a height of 2 km are reconstructed by aggregating measurements from multiple instruments, and gaps in the data are infilled with natural neighbor interpolation. We perform nine simulations using various forcing approaches to deal with data limitations. The results show that it is indeed possible to drive microscale large-eddy simulation with observations using the profile-assimilation technique, notwithstanding large gaps in virtual potential temperature measurements. However, profile assimilation with vertical smoothing of the error between the desired and actual profiles is required. Without that smoothing, the microscale simulations develop unrealistically high turbulence levels under many situations. Finally, we show that simulated mesoscale data can account for missing observations, although care is needed as both data sources are not necessarily compatible.

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Evaluation of large-eddy simulations forced with mesoscale model output for a multi-week period during a measurement campaign

Cited by 50 publications

References 90 publications

Effect of Soil Moisture on Diurnal Convection and Precipitation in Large-Eddy Simulations

Effect of Soil Moisture on Diurnal Convection and Precipitation in Large-Eddy Simulations

Transient LES of an offshore wind turbine

Using observational mean‐flow data to drive large‐eddy simulations of a diurnal cycle at the SWiFT site

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