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U.S. Wind Climatology

This product provides a spatially and temporally continuous wind climatology for the contiguous U.S. on a monthly basis from January 1950 to present. It uses NCEP Reanalysis wind data (Kalnay et al. 1996). Reanalysis data are based upon observed conditions, and a physical model is used to account for any gaps between stations and time steps. The NCEP dataset was chosen for its long period of record and its availability only a few days after the end of a month. The U.S. Department of Energy has outlined a plan for 20 percent of U.S. electricity production to be from wind by 2030, and having a temporally and spatially continuous wind dataset, updated on a monthly basis, will be beneficial to understanding wind trends nationwide. The goal of this product is to provide information on the variability and trend of wind on a monthly basis and on a regional scale. It is not intended to assist in the diagnosis of the availability of wind resources at particular locations. These types of decisions are on finer scales and involve more detailed analysis than this product alone can provide.

The sigma 995 level of the reanalysis data is used and is representative of the wind conditions in the lower troposphere. The resolution of the NCEP data is 2.5 x 2.5 degrees, and the gridded data is interpolated down to a 0.25 X 0.25 degree resolution to provide finer detail. The monthly mean wind speed and the monthly wind speed anomaly with respect to the 1971-2000 base period are calculated from the daily average U (east-west) and V (north-south) wind components and plotted for the contiguous United States. The monthly means and anomalies are also calculated and plotted for the U and V components individually. The total number of wind products and variables available is nine through this web interface, with both the plotted maps and the data available. The U and V component wind data are available through FTP at ftp://ftp.cdc.noaa.gov/Datasets/ncep.reanalysis.dailyavgs/surface/ with the file naming format uwnd.sig995.year.nc and vwnd.sig995.year.nc (where year is the 4-digit year).

Climate and wind are variable over space and time, and conditions can change considerably from month to month. This dataset provides a means to better understand long term trends for a location as well as identify non-stationarities in wind conditions. In the next update, this product will feature seasonal time series for each grid point, for the entire period of record. This will allow the comparison of regional wind conditions during different times of year to larger scale climate patterns such as ENSO or the NAO. By understanding these relationships better, the interannual and inter climate cycle variability can be taken into consideration by decision and policy makers.

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