Possible impacts on weather and climate?
Wind energy is among the world’s fastest growing sources of energy. The U.S. wind industry has experienced a remarkably rapid expansion of capacity in recent years. While converting wind’s kinetic energy into electricity, wind turbines modify surface-atmosphere exchanges and transfer of energy, momentum, mass and moisture within the atmosphere. These changes, if spatially large enough, might have noticeable impacts on local to regional weather and climate.

Given the present installed capacity and the projected growth in installation of wind farms across the world, this study draws attention to an important scientific issue that requires further investigation. We need to better understand the system with observations and better describe and model the complex processes involved to predict how wind farms may affect future weather and climate.

What will you do next?
Understanding wind farm-atmosphere interactions is a critical emerging topic. This article is a first step in exploring the potential of using satellite data to quantify the possible impacts of big wind farms on weather and climate. We are now expanding this approach to other wind farms and building models to understand the physical processes and mechanisms driving the interactions of wind turbines and the atmosphere boundary layer near the surface.

Any implications for wind energy industry?
We need to realize that the build-up of CO2 in the atmosphere due to the burning fossil fuel will have global impacts. Generating wind power creates no emissions, uses no water, and is likely green. Wind power is going to be a part of the solution to the climate change, air pollution and energy security problem. Understanding the impacts of wind farms is critical for developing efficient adaptation and management strategies to ensure long-term sustainability of wind power.

image via University of Albany/Liming Zhou

Figure 1: Nighttime land surface temperature (LST, C) differences between 2010 and 2003 (2010 minus 2003) in summer (June-July-August). Pixels with plus symbol have at least one wind turbine. A regional mean value (0.592 C) was removed to emphasize the relative LST changes at pixel level and so the resulting warming or cooling rate represents a change relative to the regional mean value. The LST data were derived from MODIS (Moderate Imaging Spectroradiometer) instruments on NASA’s Aqua and Terra satellites. Note that LST measures the radiometric temperature of the Earth’s surface itself – It has a larger diurnal variation than surface air temperature used in daily weather reports.

image via University of Albany/Liming Zhou

Figure 2: Year-to-year changes in the nighttime land surface temperature (LST, C) differences between wind farm regions and nearby non-wind farm regions for the period 2003-2011 in summer (June-July-August). The linear trend (C per decade) and its significance level (p value) estimated using least squares fitting are shown. The linear trend is to determine whether there is a deterministic long-term movement of the LST time series with time. Its magnitude represents the rate at which change occurs over time (e.g., per decade). If the value of the trend is zero, there was no trend, indicating no change with time. If the trend has a positive value, the rate is increasing. If it is negative, the rate is decreasing. The p-value tells the probability of whether the linear trend value is statistically significantly different from zero. Note that FAA data shows that the number of wind turbines over the study region increased from 111 in 2003 to 2358 in 2011.

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