The Benefits and Challenges of Downscaling a Global Reanalysis With Doubly‐Periodic Large‐Eddy Simulations

van Stratum, B. J. H.; van Heerwaarden, C. C.; Vilà‐Guerau de Arellano, J.

doi:10.1029/2023ms003750

Cited by 4 publications

(1 citation statement)

References 42 publications

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“…Large-scale tendencies are dynamically integrated in high-resolution simulations, thus overcoming several idealizations in canonical LES that relies on steady-state forcing [30]. Realistic inhomogeneous terrain can also be incorporated, which overcomes limitations of downscaling attempts with doubly-periodic boundary conditions that integrate unsteady large-scale tendencies [31,32]. The full online coupling approach is particularly important to study transient phenomena (e.g., frontal passages [33], thunderstorm outflows, baroclinic systems, low-level jets) and changes in atmospheric stability associated with the diurnal-nocturnal cycle [34], topography-induced flow [35], and to link site-specific wind conditions to the long-term climatology of the area [34].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Multiscale Large Eddy Simulations for Wind Power Production in Complex Terrain

Moliner,

Giani,

Lonati

et al. 2024

Preprint

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Coupling Large Eddy Simulations (LES) with Numerical Weather Prediction (NWP) models has promising applications for wind energy. Regional climatology, optimal siting of wind turbines as well as short term wind energy forecasts can be improved by considering all the energetic scales of atmospheric motions. However, the complexity of NWP-LES coupled simulations introduces challenges and uncertainties that need to be addressed. This study focuses on understanding the relative importance of different factors and assumptions in NWP-LES calculations for wind energy applications. Using a recent large ensemble of LES simulations driven by NWP boundary conditions over the complex terrain of the Perdigão area, our analysis reveals significant discrepancies in wind power estimates across ensemble members, particularly over hilltops. Depending on the model configuration and the coupling technique, instantaneous predictions can be as sensitive as 800kW for a 2MW wind turbine, in terms of ensemble standard deviation. On multi-day time averages, the model sensitivity is in the order of 150kW. We further analyze the main factors that lead to the observed model sensitivity. Results from a four-way ANOVA analysis identify topography and land use datasets as the primary drivers of variability, for time averaged estimates. Temporal analysis shows strong inter-daily variability and the importance of turbulence modeling and the coupling techniques for instantaneous predictions. Overall, most of the sensitivity is observed during day-to-night and synoptic transitions. By understanding the relative importance of different factors, future model development and applications can be guided to enhance the accuracy and reliability of wind energy assessments.

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Section: Introductionmentioning

confidence: 99%

Sensitivity of Multiscale Large Eddy Simulations for Wind Power Production in Complex Terrain

Moliner,

Giani,

Lonati

et al. 2024

Preprint

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The impact of coupled 3D shortwave radiative transfer on surface radiation and cumulus clouds over land

Tijhuis,

van Stratum,

van Heerwaarden

2024

Atmos. Chem. Phys.

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Abstract. Radiative transfer is a 3D process, but most atmospheric models consider radiation only in the vertical direction for computational efficiency. This results in inaccurate surface radiation fields, as the horizontal transport of radiation is neglected. Previous work on 3D radiative effects mainly used 3D radiative transfer uncoupled from the flow solver. In contrast, our current work uses 3D radiative transfer coupled to the flow solver to study its impact on the development of clouds and the resulting impact on the domain-averaged surface solar irradiance. To this end, we performed a series of realistic large-eddy simulations with MicroHH. To improve the level of realism of our radiation, we first included the direct effect of aerosols using aerosol data from the Copernicus Atmosphere Monitoring Service (CAMS) global reanalysis. Next, we performed simulations with 1D radiative transfer and with a coupled ray tracer for 12 d on which shallow cumulus clouds formed over Cabauw, the Netherlands. In general, simulations with the coupled ray tracer have a higher domain-averaged liquid water path, larger clouds, and similar cloud cover compared to simulations with 1D radiative transfer. Furthermore, the domain-averaged direct radiation is decreased with 3D radiative transfer, and the diffuse radiation is increased. However, the average difference in global radiation is less than 1 W m−2, as the increase in global radiation from uncoupled 3D radiative transfer is counterbalanced by a decrease in global radiation caused by changes in cloud properties.

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A lightweight NO₂-to-NO_x conversion model for quantifying NO_x emissions of point sources from NO₂ satellite observations

Meier,

Koene,

Krol

et al. 2024

Atmos. Chem. Phys.

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Abstract. Nitrogen oxides (NOx = NO + NO2) are air pollutants which are co-emitted with CO2 during high-temperature combustion processes. Monitoring NOx emissions is crucial for assessing air quality and for providing proxy estimates of CO2 emissions. Satellite observations, such as those from the TROPOspheric Monitoring Instrument (TROPOMI) on board the Sentinel-5P satellite, provide global coverage at high temporal resolution. However, satellites measure only NO2, necessitating a conversion to NOx. Previous studies have applied a constant NO2-to-NOx conversion factor. In this paper, we develop a more realistic model for NO2-to-NOx conversion and apply it to TROPOMI data of 2020 and 2021. To achieve this, we analysed plume-resolving simulations from the MicroHH large-eddy simulation model with chemistry for the Bełchatów (PL), Jänschwalde (DE), Matimba (ZA) and Medupi (ZA) power plants, as well as a metallurgical plant in Lipetsk (RU). We used the cross-sectional flux method to calculate NO, NO2 and NOx line densities from simulated NO and NO2 columns and derived NO2-to-NOx conversion factors as a function of the time since emission. Since the method of converting NO2 to NOx presented in this paper assumes steady-state conditions and that the conversion factors can be modelled by a negative exponential function, we validated the conversion factors using the same MicroHH data. Finally, we applied the derived conversion factors to TROPOMI NO2 observations of the same sources. The validation of the NO2-to-NOx conversion factors shows that they can account for the NOx chemistry in plumes, in particular for the conversion between NO and NO2 near the source and for the chemical loss of NOx further downstream. When applying these time-since-emission-dependent conversion factors, biases in NOx emissions estimated from TROPOMI NO2 images are greatly reduced from between −50 % and −42 % to between only −9.5 % and −0.5 % in comparison with reported emissions. Single-overpass estimates can be quantified with an uncertainty of 20 %–27 %, while annual NOx emission estimates have uncertainties in the range of 4 %–21 % but are highly dependent on the number of successful retrievals. Although more simulations covering a wider range of meteorological and trace gas background conditions will be needed to generalise the approach, this study marks an important step towards a consistent, uniform, high-resolution and near-real-time estimation of NOx emissions – especially with regard to upcoming NO2-monitoring satellites such as Sentinel-4, Sentinel-5 and CO2M.

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The Benefits and Challenges of Downscaling a Global Reanalysis With Doubly‐Periodic Large‐Eddy Simulations

Cited by 4 publications

References 42 publications

Sensitivity of Multiscale Large Eddy Simulations for Wind Power Production in Complex Terrain

Sensitivity of Multiscale Large Eddy Simulations for Wind Power Production in Complex Terrain

The impact of coupled 3D shortwave radiative transfer on surface radiation and cumulus clouds over land

A lightweight NO₂-to-NO_x conversion model for quantifying NO_x emissions of point sources from NO₂ satellite observations

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The Benefits and Challenges of Downscaling a Global Reanalysis With Doubly‐Periodic Large‐Eddy Simulations

Cited by 4 publications

References 42 publications

Sensitivity of Multiscale Large Eddy Simulations for Wind Power Production in Complex Terrain

Sensitivity of Multiscale Large Eddy Simulations for Wind Power Production in Complex Terrain

The impact of coupled 3D shortwave radiative transfer on surface radiation and cumulus clouds over land

A lightweight NO2-to-NOx conversion model for quantifying NOx emissions of point sources from NO2 satellite observations

Contact Info

Product

Resources

About

A lightweight NO₂-to-NO_x conversion model for quantifying NO_x emissions of point sources from NO₂ satellite observations