Nonlocal inadvertent weather modification associated with wind farms in the central United States

Date

2015-08

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Abstract

With the recent push for alternative, renewable energy, the wind energy industry has seen a marked boom in the United States and other countries. An interesting consequence of the creation of wind farms has been an inadvertent change in weather. The local effects within and near the farms have been well documented by a number of modeling studies and observational campaigns; however, the broader nonlocal atmospheric effects of wind farms are much less clear. In turn, there is a need to understand how wind farms are impacting the atmosphere on large temporal and spatial scales. The main goal of this study is to determine if wind farm-induced perturbations are able to evolve over periods of days, and over areas of thousands of square kilometers, to modify specific atmospheric features that have large impacts on society and the environment, specifically associated with mid-latitude and tropical cyclones.

Here we use an ensemble approach with the Advanced Research Weather Research and Forecasting mesoscale model version 3.5.1 (WRFV3.5.1) and a wind farm parameterization outlined in Fitch et al. (2012) to quantify the sensitivity of meteorological variables to the presence of wind farms. This wind farm parameterization imposes a momentum sink on the mean flow and transfers kinetic energy into electricity and turbulent kinetic energy. Ensemble variations involving wind farm locations and sizes for cases of cyclogenesis are explored to determine how perturbations evolve into significant changes to nonlocal aspects of the atmospheric state. An additional ensemble recreating unrealistic effects related to the model’s moist physics is also employed. These unrealistic effects result from the wind farm parameterization interaction with the moist physics, and are observed throughout the entire domain in select areas of convection beginning as soon as an hour after forecast initialization.

Results show that perturbations to nonlocal mid-latitude and tropical cyclones caused by a wind farm are more significant than the unrealistic perturbations to cyclones due to the moist physics. Wind farms are seen to significantly alter the cyclone minimum sea level pressure, maximum 10-m wind speed, maximum 30-min accumulated precipitation, maximum and minimum 2-m temperature, maximum and minimum 2-m potential temperature, boundary layer height, and maximum 2-m water vapor mixing ratio. Wind farm perturbations to nonlocal tropical cyclones are shown to be larger in magnitude than perturbations to mid-latitude cyclones. Also, the perturbations to mid-latitude cyclones are more dependent on wind farm size than perturbations to tropical cyclones.

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Keywords

Meteorology, Numerical Weather Prediction, Wind Energy, Cyclone, Wind Farm, Wind Turbine

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