An Observational, Spatially Explicit, Stability-Based Estimate of the Wind Resource off the Shore of North Carolina

Abstract

s part of ongoing studies of the feasibility of utility-scale wind energy off the shore of North Carolina, winds at 80-m elevation are estimated with a stability-based height-adjustment scheme. Data sources are level-3 daily Advanced Scatterometer (ASCAT) 10-m wind fields as measured by the MetOp-A satellite, North American Regional Reanalysis (NARR) estimates of near-surface atmospheric temperature and humidity, and the National Climatic Data Center?s optimally interpolated Advanced Very High Resolution Radiometer (AVHRR-OI) sea surface temperature (SST). A height-adjustment assuming neutral atmospheric stability provides reference conditions. The SST from AVHRR-OI was more accurate than SST from NARR and was used with NARR atmospheric data to represent atmospheric stability in the study region. The 5-yr average of the ASCAT 10-m winds is 6.5?9.0 m s?1 off the shore of North Carolina, with the strongest winds found over the Gulf Stream. Neutral-scheme 80-m wind speeds are 7.5?10.5 m s?1 and follow the same spatial pattern. The stability-based scheme produces an 80-m wind field with significantly different spatial wind patterns, with greater wind speeds than the neutral scheme in coastal regions where stable atmosphere conditions occur and lesser wind speeds than the neutral scheme farther offshore where unstable conditions are prevalent. The largest differences between the schemes occur in winter and spring when and where stable atmospheric conditions are most common. Estimated power inshore from the 100-m isobath with the neutral scheme yields average values of 400?800 W m?2, whereas the stability-based-scheme values are 600?800 W m?2. Capacity factors vary between 30% and 55%, with values in excess of 40% common in coastal areas off North Carolina.