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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

Seasonal mean 12:00 GMT wind speed (m/s) vertical profiles as a function of height in meters for (a) KILX and (b) KDVN. Seasonal mean wind speed (m/s) at ~80 m hub height (~293 m above sea level) is shown. The station surface elevation is 179 m for KILX and 230 m for KDVN.
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sensors-15-14981-f010: Seasonal mean 12:00 GMT wind speed (m/s) vertical profiles as a function of height in meters for (a) KILX and (b) KDVN. Seasonal mean wind speed (m/s) at ~80 m hub height (~293 m above sea level) is shown. The station surface elevation is 179 m for KILX and 230 m for KDVN.

Mentions: Composited vertical profiles of wind speed at 12:00 GMT are plotted for every season from each sounding station from the surface up to about 1000 m to display wind speeds around the rotor blades. Both sounding stations (Figure 10) reflect an increase in wind speed with altitude from the surface, which is expected given boundary layer laws, and show similar wind profiles. Averaged measurements closest to the 80 m hub-height are used to determine seasonal composite wind speeds around the rotor blades (Figure 10). The mean wind speed is strongest in MAM (7.11 m/s at KILX and 7.10 m/s at KDVN), followed by DJF (6.92 m/s at KILX and 6.87 m/s at KDVN), SON (6.59 m/s at KILX and 6.64 m/s at KDVN), and JJA (5.45 m/s at KILX and 5.76 m/s at KDVN). Note that the sounding data at 1200 GMT correspond to local solar time 6:00/7:00 a.m. over Northern Illinois when the wind speed in MAM becomes larger than that in DJF. If interpolated to the MODIS measurement times following the ASOS hourly wind speed diurnal cycle (Figure 9), the hub-height wind speed should be strongest in DJF, followed by MAM, SON and JJA, which are consistent with the ASOS results shown above. Overall, the wind speed is strongest in DJF and weakest in JJA.


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)

Seasonal mean 12:00 GMT wind speed (m/s) vertical profiles as a function of height in meters for (a) KILX and (b) KDVN. Seasonal mean wind speed (m/s) at ~80 m hub height (~293 m above sea level) is shown. The station surface elevation is 179 m for KILX and 230 m for KDVN.
© Copyright Policy
Related In: Results  -  Collection

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

sensors-15-14981-f010: Seasonal mean 12:00 GMT wind speed (m/s) vertical profiles as a function of height in meters for (a) KILX and (b) KDVN. Seasonal mean wind speed (m/s) at ~80 m hub height (~293 m above sea level) is shown. The station surface elevation is 179 m for KILX and 230 m for KDVN.
Mentions: Composited vertical profiles of wind speed at 12:00 GMT are plotted for every season from each sounding station from the surface up to about 1000 m to display wind speeds around the rotor blades. Both sounding stations (Figure 10) reflect an increase in wind speed with altitude from the surface, which is expected given boundary layer laws, and show similar wind profiles. Averaged measurements closest to the 80 m hub-height are used to determine seasonal composite wind speeds around the rotor blades (Figure 10). The mean wind speed is strongest in MAM (7.11 m/s at KILX and 7.10 m/s at KDVN), followed by DJF (6.92 m/s at KILX and 6.87 m/s at KDVN), SON (6.59 m/s at KILX and 6.64 m/s at KDVN), and JJA (5.45 m/s at KILX and 5.76 m/s at KDVN). Note that the sounding data at 1200 GMT correspond to local solar time 6:00/7:00 a.m. over Northern Illinois when the wind speed in MAM becomes larger than that in DJF. If interpolated to the MODIS measurement times following the ASOS hourly wind speed diurnal cycle (Figure 9), the hub-height wind speed should be strongest in DJF, followed by MAM, SON and JJA, which are consistent with the ASOS results shown above. Overall, the wind speed is strongest in DJF and weakest in JJA.

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