As part of a prior agreement with the North Carolina Division of Air Quality (NCDAQ), Duke Energy Corporation was required to establish an on-site ambient monitoring program at its Allen Steam Station west of Charlotte, North Carolina. Allen Steam Station is a base-load coal-fired electrical generating station. The ambient monitoring program included three SO2 monitors, and one 10-meter meteorological tower (ALN). This data, when combined with other nearby wind data, provided a unique opportunity to make an evaluation of the representativeness of the ALN wind speed data. This paper is the second of a series which examines the relationship of three wind measuring sites in the Charlotte, NC area:

• Allen Steam Station on-site (ALN)

• Charlotte National Weather Service station (CLT)

• Duke Energy Corporation’s Catawba Nuclear Station (CNS)

The data record examined for all three sites is from April 1, 2000 to March 31, 2001.

This paper specifically addresses a comparison of wind speeds measured and recorded at ALN and CNS. The interest with this comparison is that the two sites, while physically close and using identical wind measuring systems, show distinctly different wind speed patterns. CNS is 15 km southeast of ALN. Ten-meter level winds only were used, although CNS also has 60-meter level wind data. The ALN and CNS meteorological towers were equipped and maintenanced to meet or exceed PSD meteorological monitoring requirements, and hourly averaged winds were recorded. The threshold wind speed at ALN and CNS is 0.5 mph. The analysis will show graphically that the average wind speed patterns are very different, by magnitude and by direction, in spite of the proximity of the measurement systems. Intuitively, all things being equal, the ALN site should be most representative of the winds at Allen Steam Station because it is closer. Since there is no complex terrain near or between the two tower sites, the findings may indicate a unique localized effect at one or both towers which would generally be at odds with the spatially steady-state assumption of many regulatory air quality models. However, given the quality of the measurement programs in terms of equipment and quality assurance, it is not possible to determine which tower site is generally the most representative of the Charlotte area winds.