Decadal Wind Trends at the Savannah River Site

Allen H. Weber§, Robert L. Buckley, and Matthew J. Parker

Savannah River National Laboratory, Aiken, South Carolina

§ret.

§Corresponding author address: A. Weber, 820 Jackson Ave., North Augusta, SC 29841.

traviata@comcast.net

Southeast Stations Used

Wind and Temperature Observations

• NWS and SRNL data show the mean annual daytime and nighttime temperatures are increasing ~0.04 and ~0.05 ºC respectively, per year.

• The wind speed is decreasing for this area of the Southeast.

Increasing SRNL Temperature Trend

Decreasing Wind Speed Trend in the SE

Decreasing Wind Speed Trend at SRNL

Constant Sigma-Azimuth

Increasing Sigma-Elevation

Slopes of Trends

Day Night Tota l Mean Slope (per yr) Tota l

Mean Slope (per

yr) Speed (mps) 3.78 -9.00E-03 4.11 -1.41E-02

A (deg) 18.61 3.28E-02 8.02 -1.05E-02 E (deg) 12.21 9.96E-02 4.81 2.71E-02

Temperature (ºC)

19.48 3.85E-02 16.29 5.10E-02

Seasonal Slopes of Trends

Day Night Variable Season Mean Slope (per

yr) Mean Slope (per

yr) Speed (mps) Winter 4.11 -7.40E-03 4.36 -3.90E-03

Spring 4.21 -1.58E-02 4.39 -1.85E-02 Summer 3.34 -8.60E-03 3.59 -1.13E-02 Autumn 3.62 -3.00E-03 4.09 -2.29E-02

A (deg) Winter 17.60 5.90E-02 9.04 -8.18E-02 Spring 19.02 1.67E-02 8.77 9.70E-03 Summer 20.19 8.14E-02 9.38 5.11E-02 Autumn 18.88 -3.44E-02 8.09 -3.00E-04

Seasonal Slopes of Trends

Day Night Variable Season Mean Slope (per

yr) Mean Slope (per

yr)

E (deg) Winter 11.80 1.15E-01 5.71 -1.23E-02 Spring 12.64 9.76E-02 5.57 4.49E-02 Summer 13.25 1.11E-01 5.29 5.22E-02 Autumn 12.49 7.24E-02 4.92 3.49E-02

Temperature (ºC)

Winter 9.81 -6.54E-02 8.71 -4.82E-02

Spring 18.96 9.10E-02 16.73 9.53E-02 Summer 26.46 2.28E-02 24.18 4.29E-02 Autumn 19.56 8.52E-02 17.50 1.11E-01

E and A for Daytime and Nighttime

E for daytime and nighttime from SRNL Area Towers is increasing at a rate of ~0.03 and ~0.01 degrees per year, respectively.

A for daytime from the SRNL Area Towers is increasing at a rate of ~0.03 degrees per year. Nighttime values are decreasing by ~0.10 degrees per year.

Conclusions

• Daytime and nighttime temperatures are increasing ~4 and ~5 ºC respectively, per century.

• Daytime and nighttime speeds are decreasing ~0.9 and ~1.4 m/s respectively, per century

• Increases in E for daytime and nighttime suggest that convective turbulence is increasing. This is probably due to a decrease in the thermal stability between the surface and the 60-m level.

• The daytime rate for E is increasing more rapidly than the nighttime rate.