Free-Flow Variability on the Jess and Souza Ranches, Altamont Pass

This report is one of a series of such documents that present the findings of field tests conducted under the Department of Energy's (DOE) Cooperative Field Test Program with the U.S. wind industry. The report provides the results of a study to collect data at two windfarms. The two wind turbine arrays, located in the Altamont Pass east of San Francisco, were instrumented with anemometers and acentral monitoring computer. To obtain a high spatial density of wind-speed measurements, every other turbine in both arrays was instrumented. Wind-speed data were collected over a period of four days during the summer high-wind season with all turbines shut down. The resultant data set was analyzed to determine the spatial variability of the wind resource in the two arrays. Because no turbinewakes were present, variation in the flow was caused by the interaction of the flow with the terrain and was not a function of turbine wake interaction. The free-flow data sets can be used by other researchers to refine numerical free-flow computer models. The data sets will be used to fine tune and validate these computer models. In addition, the free-flow data will be compared to results of awake energy deficit study also under way on these turbine arrays.