WRF-Simulated Low-Level Jets over Iowa: Characterization
and Sensitivity Studies

Aird, Jeanie A.; Barthelmie, R.J.; Shepherd, Tristan J.; Pryor, Sara C.

doi:10.5194/wes-2020-113

Cited by 3 publications

(3 citation statements)

References 34 publications

(46 reference statements)

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“…The first criterion was used to reflect the reduced frictional effects in the nocturnal boundary layer as pre-requisite for the formation of NLLJs. According to Aird et al (2021), the use of a absolute criterion ensures that high-speed NLLJs are detected more reliably, and relative values can extract a higher number of NLLJs with lower wind speed maxima and higher duration.…”

Section: Automated Nllj Detectionmentioning

confidence: 99%

“…Potential reasons are multiple and include the common artificial enhancement of the turbulent mixing during stable stratification to represent unresolved processes, e.g., vertical mixing associated with surface heterogeneity, gravity waves and sub-grid-scale variability (Sandu et al, 2013). Reanalysis data can share similar biases for the nearsurface wind profile, and coarse vertical and spatial resolutions, including terrain discretization, are an additional contributing factor to those biases (Kalverla et al, 2019;Hallgren et al, 2020;Aird et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Spatiotemporal observations of nocturnal low-level jets and impacts on wind power production

Luiz

Fiedler

2022

Wind Energ. Sci.

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Abstract. A challenge of an energy system that nowadays more strongly depends on wind power generation is the spatial and temporal variability in winds. Nocturnal low-level jets (NLLJs) are typical wind phenomena defined as a maximum in the vertical profile of the horizontal wind speed. A NLLJ has typical core heights of 50–500 m a.g.l. (above ground level), which is in the height range of most modern wind turbines. This study presents NLLJ analyses based on new observations from Doppler wind lidars. The aim is to characterize the temporal and spatial variability in NLLJs on the mesoscale and to quantify their impacts on wind power generation. The data were collected during the Field Experiment on Submesoscale Spatio-Temporal Variability (FESSTVaL) campaign from June to August 2020 in Lindenberg and Falkenberg (Germany), located at about 6 km from each other. Both sites have seen NLLJs in about 70 % of the nights with half of them lasting for more than 3 h. Events longer than 6 h occurred more often simultaneously at both sites than shorter events, indicating the mesoscale character of very long NLLJs. Very short NLLJs of less than 1 h occurred more often in Lindenberg than Falkenberg, indicating more local influences on the wind profile. We discussed different meteorological mechanisms for NLLJ formation and linked NLLJ occurrences to synoptic weather patterns. There were positive and negative impacts of NLLJs on wind power that we quantified based on the observational data. NLLJs increased the mean power production by up to 80 % and were responsible for about 25 % of the power potential during the campaign. However, the stronger shear in the rotor layer during NLLJs can also have negative impacts. The impacts of NLLJs on wind power production depended on the relative height between the wind turbine and the core of the NLLJ. For instance, the mean increase in the estimated power production during NLLJ events was about 30 % higher for a turbine at 135 m a.g.l. compared to one at 94 m a.g.l. Our results imply that long NLLJs have an overall stronger impact on the total power production, while short events are primarily relevant as drivers for power ramps.

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Section: Automated Nllj Detectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spatiotemporal observations of nocturnal low-level jets and impacts on wind power production

Luiz

Fiedler

2022

Wind Energ. Sci.

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“…Extreme weather phenomena such as low-level jets, fast changes in wind direction, extreme wind shear (Kalverla et al, 2017;Aird et al, 2021), wind ramps (Gallego-Castillo et al, 2015), and storms (Solari, 2020) are capable of causing severe dynamic loading on wind turbines (Negro et al, 2014;AbuGazia et al, 2020;Chi et al, 2020). Furthermore, precipitation associated with these phenomena can lead to early blade degradation through leading-edge erosion (Law and Koutsos, 2020).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity analysis of mesoscale simulations to physics parameterizations over the Belgian North Sea using Weather Research and Forecasting – Advanced Research WRF (WRF-ARW)

et al. 2022

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Abstract. The Weather Research and Forecasting (WRF) model offers a multitude of physics parameterizations to study and analyze the different atmospheric processes and dynamics that are observed in the Earth's atmosphere. However, the suitability of a WRF model setup is known to be highly sensitive to the type of weather phenomena and the type and combination of physics parameterizations. A multi-event sensitivity analysis is conducted to identify general trends and suitable WRF physics setups for three extreme weather events identified to be potentially harmful for the operation and maintenance of wind farms located in the Belgian offshore concession zone. The events considered are Storm Ciara on 10 February 2020, a low-pressure system on 24 December 2020, and a trough passage on 27 June 2020. A total of 12 WRF simulations per event are performed to study the effect of the update interval of lateral boundary conditions and different combinations of physics parameterizations (planetary boundary layer, PBL; cumulus; and microphysics). Specifically, the update interval of ERA5 lateral boundary conditions is varied between hourly and 3-hourly. Physics parameterizations are varied between three PBL schemes (Mellor–Yamada–Nakanishi–Niino, MYNN; scale-aware Shin-Hong; and scale-aware Zhang), four cumulus schemes (Kain–Fritsch, Grell–Dévényi, scale-aware Grell–Freitas, and multi-scale Kain–Fritsch), and three microphysics schemes (WRF Single-Moment five-class scheme, WSM5; Thompson; and Morrison). The simulated wind direction and wind speed are compared qualitatively and quantitatively to operational supervisory control and data acquisition (SCADA) data. Overall, a definitive best-case setup common to all three events is not identified in this study. For wind direction and wind speed, the best-case setups are identified to employ scale-aware PBL schemes. These are most often driven by hourly update intervals of lateral boundary conditions as opposed to 3-hourly update intervals, although it is only in the case of Storm Ciara that significant differences are observed. Scale-aware cumulus schemes are identified to produce better results when combined with scale-aware PBL schemes, specifically for Storm Ciara and the trough passage cases. However, for the low-pressure-system case this trend is not observed. No clear trend in utilizing higher-order microphysics parameterization considering the combinations of WRF setups in this study is found in all cases. Overall, the combination of PBL, cumulus, and microphysics schemes is found to be highly sensitive to the type of extreme weather event. Qualitatively, precipitation fields are found to be highly sensitive to model setup and the type of weather phenomena.

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Spatio-temporal observations of nocturnal low-level jets and impacts on wind power production

Luiz

Fiedler

2022

Preprint

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Abstract. A challenge of an energy system, that nowadays more strongly depends on wind power generation, is the spatial and temporal variability of winds. Nocturnal low-level jets (NLLJ) are typical wind phenomena defined as a maximum in the vertical profile of the horizontal wind speed. A NLLJ has typical core heights of 50–500 m above ground level (a.g.l.), which is in the height range of most modern wind turbines. This study presents NLLJ analyses based on new observations from Doppler wind LiDARs. The aim is to characterize the temporal and spatial variability of NLLJs on the mesoscale and to quantify their impacts on wind power generation. The data was collected during the Field Experiment on Submesoscale Spatio-Temporal Variability (FESSTVaL) campaign from June to August 2020 in Lindenberg and Falkenberg (Germany), located at about 6 km from each other. Both sites have seen NLLJs in about 70 % of the nights with half of them lasting for more than 3 hours. Events longer than 6 hours occurred more often simultaneously at both sites than shorter events, indicating the mesoscale character of very long NLLJs. Very short NLLJs of less than one hour occurred more often in Lindenberg than Falkenberg, indicating more local influences on the wind profile. We discussed different meteorological mechanisms for NLLJ formation and linked NLLJ occurrences to synoptic weather patterns. There were positive and negative impacts of NLLJs on wind power that we quantified based on the observational data. While NLLJs increased the mean power production by up to 80 %, the stronger shear in the rotor layer during NLLJs had also negative impacts. The impacts of NLLJs on wind power production depended on the relative height between the wind turbine and the core of the NLLJ. For instance, the mean increase of the estimated power production during NLLJ events was about 30 % higher for a turbine at 135 m a.g.l. compared to one at 94 m a.g.l.. Our results imply that long NLLJs have an overall stronger impact on the total power production, while short events are primarily relevant as driver for power ramps.

show abstract

WRF-Simulated Low-Level Jets over Iowa: Characterization and Sensitivity Studies

Cited by 3 publications

References 34 publications

Spatiotemporal observations of nocturnal low-level jets and impacts on wind power production

Spatiotemporal observations of nocturnal low-level jets and impacts on wind power production

Sensitivity analysis of mesoscale simulations to physics parameterizations over the Belgian North Sea using Weather Research and Forecasting – Advanced Research WRF (WRF-ARW)

Spatio-temporal observations of nocturnal low-level jets and impacts on wind power production

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