Table A-2 Principal Sources of Wind Data

Source Description

National Climatic Data Center

  National Wind Data Index

  Index of Original Surface Weather

The National Wind Data Index (Changery 1978) is a concise listing of the periods of record of all available wind observations in the NCDC's meterological (data) archives for locations in the United States. Included are the periods with various types of manuscript records and autographic charts containing wind data, the approximate number of observations per day, and periods for which wind data are on magnetic tape. For most locations, the anemometer heights are included together with dates of height changes and the instrument exposure. The Index of Original Surface Weather Records, published for each individual state by the NCDC, provides additional information about stations at which wind data have been taken.

  Index - Summarized
   Wind Data
The wind data available from the NCDC may be in one or more of three formats: summarized, digitized, and unsummarized. Initially, all wind data are in the unsummarized format consisting of the original station weather records. For many stations, the collection of individual observations has been condensed into wind summaries for selected periods. The Index - Summarized Wind Data (Changery et al. 1977) is a listing of locations and periods for which summaries in various formats are available from the NCDC. The majority of summaries present the frequency or percentage of observations of the wind speed in various speed classes (1 to 3 mph, 4 to 7 mph, etc.) for each of 8,16, or 36 compass points. Data for a given number of years are summarized on a monthly and/or seasonal and/or annual basis

  Digitized TD-1440 Data For approximately 100 stations in the U.S., the NCDC has digitized selected periods of one- or three-hourly surface weather observations on magnetic tape. These data tapes are commonly referred to as TD-1440 tapes. PNL processed and summarized the wind data on these tapes for stations in all states and U.S. territories. In contrast to many summarizations routinely available from the NCDC, PNL's analyses examine the wind record only for periods of constant anemometer height, location, and observation frequency. For each such period, various statistics summarizing the wind resource were determined. These summaries have been included in a national wind energy data base organized by PNL (Barchet 1980).

Forest Service

  U.S. Forest Service

The U.S. Forest Service data in the National Fire Weather Data Library (NFDL) are from remote sites in mountainous and forested areas under the jurisdiction of the Federal government (Furman and Brink 1975). About 1700 stations with wind data are reported in the NFDL for the U.S. However, only one afternoon observation, at about 2 p.m., is digitized per day during the local fire weather season.

An assessment of the applicability of the NFDL to wind energy analysis, based on data from about 700 stations in the Northwest region, found that data from only a small percentage of the fire weather stations may be useful in wind energy assessments (Marlatt et al 1979). Nevertheless, these data often provide the only wind resource information from remote areas where conventional data are not available. For this reason, summaries of seasonal average wind speeds and power densities were generated for over 1700 fire weather stations in the U.S. and provided to the regional wind atlas contractors for evaluation.

  California Department of Forestry The California Department of Forestry also maintained a network of nearly 200 lookouts and guard stations in areas under its jurisdiction. Seven observations per day (from 7 a.m. to 6 p.m.) were recorded at these sites during the local fire season.
Other Sources

  Power Plant Data

Wind data from existing or planned nuclear or fossil-fueled power plant sites provided a valuable addition to the existing NCDC station data, in that multilevel tower data were available from many of the sites. The Summary of Wind Data From Nuclear Power Plant Sites (Verholek 1977) contains wind summaries for 104 sites in the U.S.
  International Data To assess the wind energy resource in areas of the U.S. near the international boundaries, wind data from Canada and Mexico were identified to supplement the existing data within the U.S. These data were obtained from the Atmospheric Environment Service of Canada and the Mexican Hydrological Service.

  Coastal Marine Data Service station data in coastal areas were supplemented by summarized wind data from coastal marine areas, which are primarily based on ship wind observations over many years. The coastal marine wind data examined in the regional wind energy atlases came from several publications: Climatic Study of the Near Coastal Zone (Naval Weather Service Detachment 1976), Summary of Synoptic Meteorological Observations: North American Coastal Marine Areas - Revised (U.S. Naval Oceanography Command 1975), Environmental Guide for the U.S. Gulf Coast (NCDC 1972), and Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska (NCDC and the University of Alaska 1977). For the wind energy assessment of Hawaii and the Pacific Islands, supplementary data were obtained from an extensive collection of ship observations available from the University of Hawaii (Wyrtki and Meyers 1975). For the assessments of Puerto Rico and the U.S. Virgin Islands, supplementary data were obtained for two marine areas of the Caribbean Sea (Naval Weather Service Department 1974).

  Upper-air Data Since existing surface data from mountain summits and ridge crests were very sparse, upper-air wind data were identified for potential use in estimating the free-air wind speeds at exposed sites in mountainous regions. Several sets of upper-air wind data available from the NCDC were identified for this purpose. Upper Wind Statistics of the Northern Hemisphere (Crutcher 1959) provides wind climatologies for the 850, 700, and 500 mb constant pressure levels. Winds Aloft Summaries (NCDC 1970) provides wind summaries at the 150 m and 300 m levels above the surface and 500 m or 1000 m above sea level for 66 sites in the U.S. Over Alaska, the estimation of wind power over mountains made use of Meridional Cross Sections, Upper Winds Over the Northern Hemisphere (Crutcher 1961). Over Hawaii and the Pacific Islands, tropical upper-air wind climatologies (Wiederangers 1961) and satellite-derived winds supplemented the NCDC winds aloft summaries. Supplementary upper-air wind summaries were also identified for potential use in the wind resource assessments of Puerto Rico and the U.S. Virgin Islands.