Limits...
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 MODIS nighttime LST differences (°C) between the pre- and post- turbine construction period (2010–2013 minus 2003–2006 averages) in (a) DJF; (b) MAM; (c) JJA and (d) SON. Plus symbols represent pixels with at least one wind turbine.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4541818&req=5

sensors-15-14981-f005: Seasonal mean MODIS nighttime LST differences (°C) between the pre- and post- turbine construction period (2010–2013 minus 2003–2006 averages) in (a) DJF; (b) MAM; (c) JJA and (d) SON. Plus symbols represent pixels with at least one wind turbine.

Mentions: The nighttime LST difference plots between the pre- and post- turbine construction period for each season are shown in Figure 5. The spatial coupling of warming with the wind turbines is evident in every season, and this coupling is the tightest in JJA, followed by SON and MAM, and the weakest in DJF, which is consistent with the quantitative analysis using the SCI index described below. In general, the shift of the warming toward the northeast corresponds to climatological wind directions from the west, southwest and south, and the magnitude of warming corresponds to the strength of wind speed at hub-height (see more discussion later). The strength of the spatial coupling is also related to the magnitude of inter-annual variability in LST (Figure 3) associated with variable weather events: larger variability causes the widespread warming seen in MAM and DJF, while less variability in SON and JJA generally mimic the overall annual variations, which are consistent with Zhou et al. [18]. Consequently, JJA, SON, and ANN have the tightest spatial coupling of nighttime warming with the wind turbines (Figure 4 and Figure 5).


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 MODIS nighttime LST differences (°C) between the pre- and post- turbine construction period (2010–2013 minus 2003–2006 averages) in (a) DJF; (b) MAM; (c) JJA and (d) SON. Plus symbols represent pixels with at least one wind turbine.
© Copyright Policy
Related In: Results  -  Collection

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

sensors-15-14981-f005: Seasonal mean MODIS nighttime LST differences (°C) between the pre- and post- turbine construction period (2010–2013 minus 2003–2006 averages) in (a) DJF; (b) MAM; (c) JJA and (d) SON. Plus symbols represent pixels with at least one wind turbine.
Mentions: The nighttime LST difference plots between the pre- and post- turbine construction period for each season are shown in Figure 5. The spatial coupling of warming with the wind turbines is evident in every season, and this coupling is the tightest in JJA, followed by SON and MAM, and the weakest in DJF, which is consistent with the quantitative analysis using the SCI index described below. In general, the shift of the warming toward the northeast corresponds to climatological wind directions from the west, southwest and south, and the magnitude of warming corresponds to the strength of wind speed at hub-height (see more discussion later). The strength of the spatial coupling is also related to the magnitude of inter-annual variability in LST (Figure 3) associated with variable weather events: larger variability causes the widespread warming seen in MAM and DJF, while less variability in SON and JJA generally mimic the overall annual variations, which are consistent with Zhou et al. [18]. Consequently, JJA, SON, and ANN have the tightest spatial coupling of nighttime warming with the wind turbines (Figure 4 and Figure 5).

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