Measurements of heat and humidity fluxes in the wake of offshore wind turbines

Foreman, Richard; Cañadillas, Beatriz; Neumann, Thomas; Emeis, Stefan

doi:10.1063/1.5003811

Cited by 14 publications

(11 citation statements)

References 34 publications

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“…For the estimation of the friction velocity u ∗ in the marine boundary layer, sonic data from the research mast FINO1 at 40 m above the sea surface was used. FINO1 is a meteorological measurement tower located about 45 km offshore, north of the German Island Borkum in the German Bight (see Figure 1) and is equipped among others with 20 Hz high frequency sonic anemometers 26 . Further, mean temperature and wind data at several heights from FINO1 and FINO3 (a second measurement tower located north of the wind farm AW) is used for vertical profiling of the lowest boundary layer between the sea surface and 100 m.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of a simple analytical model for offshore wind farm wake recovery by in situ data and Weather Research and Forecasting simulations

et al. 2020

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The recovery of offshore wind farm wakes in the German Bight was analyzed by a unique in situ data set, measured on‐board the research aircraft Dornier Do‐128 during the WIPAFF project in 2016 and 2017. These observations were used to validate a simple analytical wake recovery model in five case studies. The observed recovery rates were compared with the results of the mesoscale Weather Research and Forecasting (WRF) model. The airborne data show that the wake recovery can be described by an exponential function as expected by the analytical model and strengthens the hypothesis that the vertical downward moment flux has an important influence on the wake recovery. However, the predicted wake recovery rates (by the analytical model) do not always fully agree with the observations. Although, as a first‐order approximation, the model seems to perform well, further optimization has to be implemented to account for wind park layout, turbine induced turbulence, and horizontal momentum flux. WRF simulations reveal an exponential recovery, although the mesoscale model does not reproduce the correct atmospheric conditions for most of the cases. Therefore, the wake recovery rates estimated by WRF disagree with the measured data in most of the studied cases.

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Section: Methodsmentioning

confidence: 99%

Evaluation of a simple analytical model for offshore wind farm wake recovery by in situ data and Weather Research and Forecasting simulations

et al. 2020

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“…Moreover, R H is assumed to be 100 % at the water surface (0 m). For θ v at the water surface, the temperature is derived from the water temperature measurement of the buoy similar to the method by Foreman et al (2017) who used the sea surface as a proxy for the lapse-rate calculation. Data are averaged over a 10-min period, which is identical to the airborne measurements.…”

Section: Data Acquisitionmentioning

confidence: 99%

The Role of Atmospheric Stability and Turbulence in Offshore Wind-Farm Wakes in the German Bight

Platis

Hundhausen

Lampert

et al. 2021

Boundary-Layer Meteorol

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Airborne meteorological in situ measurements as well as stationary measurements at the offshore masts FINO1 and FINO3 in the German Bight are evaluated in order to examine the hypothesis that the wake dissipation downstream of large offshore wind farms depends on atmospheric stability. A long-term study of the mast data for the years 2016 and 2017 demonstrates a clear dependence of stability on the wind direction. Stable conditions are predominantly expected during southerly winds coming from the land. The analysis of various stability and turbulence criteria shows that the lapse rate is the most robust parameter for stability classification in the German Bight, but further implies that stability depends on the measurement height. A near-surface (0 to 30 m), predominantly convective, layer is present and more stable conditions are found aloft (55 to 95 m). Combing the stability data with the airborne measurements of the offshore wind-farm wakes reveals the trend of a correlation between longer wake lengths and an increase in the initial wind-speed deficit downwind of a wind farm with stronger thermal stability. However, the stability correlation criteria with the wake length downstream of the four investigated wind farms, Godewind, Amrumbank West, Meerwind Süd/Ost, and Nordsee Ost, contain large variance. It is assumed that the observed scattering is due to the influence of the wind-farm architecture and temperature inversions around hub height. These, however, are crucial for the classification of stability and illustrate the complexity of a clear stability metric.

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“…The impact of inhomogeneous terrain on the turbulent exchange processes between the ground and the atmospheric boundary layer was investigated by Bange et al (2002Bange et al ( , 2006. Convective processes up to the formation of thunderstorms in the atmosphere were studied by direct measurements in the clouds and drop sondes released from the aircraft (Groenemeijer et al, 2009). The aircraft was deployed above the Mediterranean to investigate cyclones and mesoscale convective systems to understand which atmospheric conditions lead to devastating thunderstorms, and to improve the forecasting of such systems Ducrocq et al, 2014;Sodemann et al, 2017).…”

Section: Research Aircraft Dornier 128mentioning

confidence: 99%

In situ airborne measurements of atmospheric and sea surface parameters related to offshore wind parks in the German Bight

Lampert

Bärfuss

Platis

et al. 2020

Earth Syst. Sci. Data

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Abstract. Between 6 September 2016 and 15 October 2017, meteorological measurement flights were conducted above the German Bight in the framework of the project WIPAFF (Wind Park Far Field). The scope of the measurements was to study long-range wakes with an extent larger than 10 km behind entire wind parks, and to investigate the interaction of wind parks and the marine atmospheric boundary layer. The research aircraft Dornier 128 of the Technische Universität (TU) Braunschweig performed in total 41 measurement flights during different seasons and different stability conditions. The instrumentation consisted of a nose boom with sensors for measuring the wind vector, temperature and humidity, and additionally sensors for characterizing the water surface, a surface temperature sensor, a laser scanner and two cameras in the visible and infrared wavelength range. A detailed overview of the aircraft, sensors, data post-processing and flight patterns is provided here. Further, averaged profiles of atmospheric parameters illustrate the range of conditions. The potential use of the data set has been shown already by first publications. The data are publicly available in the world data centre PANGAEA (https://doi.org/10.1594/PANGAEA.902845; Bärfuss et al., 2019a).

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Measurements of heat and humidity fluxes in the wake of offshore wind turbines

Cited by 14 publications

References 34 publications

Evaluation of a simple analytical model for offshore wind farm wake recovery by in situ data and Weather Research and Forecasting simulations

Evaluation of a simple analytical model for offshore wind farm wake recovery by in situ data and Weather Research and Forecasting simulations

The Role of Atmospheric Stability and Turbulence in Offshore Wind-Farm Wakes in the German Bight

In situ airborne measurements of atmospheric and sea surface parameters related to offshore wind parks in the German Bight

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