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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

ASOS seasonal mean diurnal (hourly) cycle of wind speed (m/s) at 10 m height for Pontiac, IL (PNT). The two vertical gray lines represent the Terra and Aqua data collection times at ~22:30 p.m. and ~1:30 a.m. The x-axis is time starting at 12 noon on the left, 0 mid-night in the center, and 11 a.m. on the right. Seasonal mean wind speed (m/s) at 10 m averaged between 22:00 p.m. and ~2:00 a.m. is shown.
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sensors-15-14981-f009: ASOS seasonal mean diurnal (hourly) cycle of wind speed (m/s) at 10 m height for Pontiac, IL (PNT). The two vertical gray lines represent the Terra and Aqua data collection times at ~22:30 p.m. and ~1:30 a.m. The x-axis is time starting at 12 noon on the left, 0 mid-night in the center, and 11 a.m. on the right. Seasonal mean wind speed (m/s) at 10 m averaged between 22:00 p.m. and ~2:00 a.m. is shown.

Mentions: The diurnal cycle of hourly seasonal composite wind speed (Figure 9) is representative of the turbulence caused by rising thermals in the daytime and calmer surface wind speeds at night in the SBL. Overall slower wind speeds are seen at nighttime with winds ramping up during the day due to solar heating. As the sun heats the ground, rising warm air mixes the atmosphere and faster winds are produced through all levels. At night with no solar heating the atmosphere is able to become stably stratified again as a result of radiative cooling. The wind speed averaged during the MODIS nighttime collection times (Figure 9) is strongest in DJF (4.54 m/s), followed by MAM (4.16 m/s), SON (3.16 m/s) and JJA (2.00 m/s). Overall, the wind speed in JJA is evidently smaller than that in the other three seasons.


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)

ASOS seasonal mean diurnal (hourly) cycle of wind speed (m/s) at 10 m height for Pontiac, IL (PNT). The two vertical gray lines represent the Terra and Aqua data collection times at ~22:30 p.m. and ~1:30 a.m. The x-axis is time starting at 12 noon on the left, 0 mid-night in the center, and 11 a.m. on the right. Seasonal mean wind speed (m/s) at 10 m averaged between 22:00 p.m. and ~2:00 a.m. is shown.
© Copyright Policy
Related In: Results  -  Collection

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

sensors-15-14981-f009: ASOS seasonal mean diurnal (hourly) cycle of wind speed (m/s) at 10 m height for Pontiac, IL (PNT). The two vertical gray lines represent the Terra and Aqua data collection times at ~22:30 p.m. and ~1:30 a.m. The x-axis is time starting at 12 noon on the left, 0 mid-night in the center, and 11 a.m. on the right. Seasonal mean wind speed (m/s) at 10 m averaged between 22:00 p.m. and ~2:00 a.m. is shown.
Mentions: The diurnal cycle of hourly seasonal composite wind speed (Figure 9) is representative of the turbulence caused by rising thermals in the daytime and calmer surface wind speeds at night in the SBL. Overall slower wind speeds are seen at nighttime with winds ramping up during the day due to solar heating. As the sun heats the ground, rising warm air mixes the atmosphere and faster winds are produced through all levels. At night with no solar heating the atmosphere is able to become stably stratified again as a result of radiative cooling. The wind speed averaged during the MODIS nighttime collection times (Figure 9) is strongest in DJF (4.54 m/s), followed by MAM (4.16 m/s), SON (3.16 m/s) and JJA (2.00 m/s). Overall, the wind speed in JJA is evidently smaller than that in the other three seasons.

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