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Observed Thermal Impacts of Wind Farms Over Northern Illinois.

Slawsky LM, Zhou L, Baidya Roy S, Xia G, Vuille M, Harris RA - Sensors (Basel) (2015)

Bottom Line: The nighttime LST warming effect varies with seasons, with the strongest warming in winter months of December-February, and the tightest spatial coupling in summer months of June-August.Although the warming effect is strongest in winter, the spatial coupling is more erratic and spread out than in summer.These results suggest that the observed warming signal at nighttime is likely due to the net downward transport of heat from warmer air aloft to the surface, caused by the turbulent mixing in the wakes of the spinning turbine rotor blades.

View Article: PubMed Central - PubMed

Affiliation: Department of Atmospheric and Environmental Sciences, SUNY at Albany, Albany, NY 12222, USA. lslawsky@albany.edu.

ABSTRACT
This paper assesses impacts of three wind farms in northern Illinois using land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellites for the period 2003-2013. Changes in LST between two periods (before and after construction of the wind turbines) and between wind farm pixels and nearby non-wind-farm pixels are quantified. An areal mean increase in LST by 0.18-0.39 °C is observed at nighttime over the wind farms, with the geographic distribution of this warming effect generally spatially coupled with the layout of the wind turbines (referred to as the spatial coupling), while there is no apparent impact on daytime LST. The nighttime LST warming effect varies with seasons, with the strongest warming in winter months of December-February, and the tightest spatial coupling in summer months of June-August. Analysis of seasonal variations in wind speed and direction from weather balloon sounding data and Automated Surface Observing System hourly observations from nearby stations suggest stronger winds correspond to seasons with greater warming and larger downwind impacts. The early morning soundings in Illinois are representative of the nighttime boundary layer and exhibit strong temperature inversions across all seasons. The strong and relatively shallow inversion in summer leaves warm air readily available to be mixed down and spatially well coupled with the turbine. Although the warming effect is strongest in winter, the spatial coupling is more erratic and spread out than in summer. These results suggest that the observed warming signal at nighttime is likely due to the net downward transport of heat from warmer air aloft to the surface, caused by the turbulent mixing in the wakes of the spinning turbine rotor blades.

No MeSH data available.


Related in: MedlinePlus

Regional mean interannual MODIS nighttime LST anomalies (°C) over the study region for the four seasons (DJF, MAM, JJA, and SON) and annual mean (ANN). Standard deviations of LST anomalies are shown.
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sensors-15-14981-f003: Regional mean interannual MODIS nighttime LST anomalies (°C) over the study region for the four seasons (DJF, MAM, JJA, and SON) and annual mean (ANN). Standard deviations of LST anomalies are shown.

Mentions: The LST shows strong interannual variability over the study region. Figure 3 illustrates the regional mean LST anomalies at nighttime and their standard deviations (STDs) from 2003 to 2013. DJF LST changes substantially due to variable winter weather systems each year. MAM LST also displays much variability from year to year. Above average LSTs in these seasons greatly impact the ANN LST in 2007 and 2012. A strong negative LST anomaly in DJF in 2011 of nearly 4.0 °C below average reduced the annual LST, even though this year was 2.0 °C warmer than average in JJA. The STD is largest in DJF (2.07 °C), followed by MAM (1.46 °C), JJA (1.19 °C), and SON (0.73 °C). The high-frequency LST variability will mask to some extent the wind farm induced low-frequency LST signal [18,19], particularly in the winter months (see more discussion later).


Observed Thermal Impacts of Wind Farms Over Northern Illinois.

Slawsky LM, Zhou L, Baidya Roy S, Xia G, Vuille M, Harris RA - Sensors (Basel) (2015)

Regional mean interannual MODIS nighttime LST anomalies (°C) over the study region for the four seasons (DJF, MAM, JJA, and SON) and annual mean (ANN). Standard deviations of LST anomalies are shown.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541818&req=5

sensors-15-14981-f003: Regional mean interannual MODIS nighttime LST anomalies (°C) over the study region for the four seasons (DJF, MAM, JJA, and SON) and annual mean (ANN). Standard deviations of LST anomalies are shown.
Mentions: The LST shows strong interannual variability over the study region. Figure 3 illustrates the regional mean LST anomalies at nighttime and their standard deviations (STDs) from 2003 to 2013. DJF LST changes substantially due to variable winter weather systems each year. MAM LST also displays much variability from year to year. Above average LSTs in these seasons greatly impact the ANN LST in 2007 and 2012. A strong negative LST anomaly in DJF in 2011 of nearly 4.0 °C below average reduced the annual LST, even though this year was 2.0 °C warmer than average in JJA. The STD is largest in DJF (2.07 °C), followed by MAM (1.46 °C), JJA (1.19 °C), and SON (0.73 °C). The high-frequency LST variability will mask to some extent the wind farm induced low-frequency LST signal [18,19], particularly in the winter months (see more discussion later).

Bottom Line: The nighttime LST warming effect varies with seasons, with the strongest warming in winter months of December-February, and the tightest spatial coupling in summer months of June-August.Although the warming effect is strongest in winter, the spatial coupling is more erratic and spread out than in summer.These results suggest that the observed warming signal at nighttime is likely due to the net downward transport of heat from warmer air aloft to the surface, caused by the turbulent mixing in the wakes of the spinning turbine rotor blades.

View Article: PubMed Central - PubMed

Affiliation: Department of Atmospheric and Environmental Sciences, SUNY at Albany, Albany, NY 12222, USA. lslawsky@albany.edu.

ABSTRACT
This paper assesses impacts of three wind farms in northern Illinois using land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellites for the period 2003-2013. Changes in LST between two periods (before and after construction of the wind turbines) and between wind farm pixels and nearby non-wind-farm pixels are quantified. An areal mean increase in LST by 0.18-0.39 °C is observed at nighttime over the wind farms, with the geographic distribution of this warming effect generally spatially coupled with the layout of the wind turbines (referred to as the spatial coupling), while there is no apparent impact on daytime LST. The nighttime LST warming effect varies with seasons, with the strongest warming in winter months of December-February, and the tightest spatial coupling in summer months of June-August. Analysis of seasonal variations in wind speed and direction from weather balloon sounding data and Automated Surface Observing System hourly observations from nearby stations suggest stronger winds correspond to seasons with greater warming and larger downwind impacts. The early morning soundings in Illinois are representative of the nighttime boundary layer and exhibit strong temperature inversions across all seasons. The strong and relatively shallow inversion in summer leaves warm air readily available to be mixed down and spatially well coupled with the turbine. Although the warming effect is strongest in winter, the spatial coupling is more erratic and spread out than in summer. These results suggest that the observed warming signal at nighttime is likely due to the net downward transport of heat from warmer air aloft to the surface, caused by the turbulent mixing in the wakes of the spinning turbine rotor blades.

No MeSH data available.


Related in: MedlinePlus