Historical evolution of wind climates in the USA

Near-surface wind speeds over the contiguous USA generally declined between 1973 and 2005. These trends are statistically robust and are not demonstrably the result of changing anemometer technology. The trends are regionally coherent - with sites in the eastern USA generally indicating declining wind speeds, while in the western states approximately equal numbers of stations exhibit positive and negative trends and a large number exhibit trends that are not statistically significant. The trends are not monotonic and at over half of sites studied embedded within the data period of 1973-2005 are periods of reverse trends. Nevertheless, the start of the data period is characterized by higher energy density than the end at the majority of stations analysed.