Wind Speed Distribution of Montana, 2002

Data Provider TrueWind Solutions
Date 2002
Content Type Downloadable Data
Abstract Estimated wind speed distribution of Montana. This is a raster data set in which each 400-meter pixel represents the average speed of the wind in meters per second at an elevation of 50 meters above the ground. These wind speed estimates were produced by TrueWind Solutions using their Mesomap system and historical weather data. This map has been validated with available suface data by the National Renewable Energy Laboratory and wind energy meteorological consultants. The estimates tend to be more accurate for the plains than for mountainous areas. For more information, see and read the Use_Constraints section below.
Supplemental Information
The wind resource estimates were developed using MesoMap, a wind mapping system developed by TrueWind Solutions. MesoMap combines two models, MASS, a mesoscale atmospheric simulation model similar to a weather forecasting model, and WindMap, a simpler wind flow model. The results were validated by the National Renewable Energy Laboratory (NREL) and independent meteorologists using historical data. Wind speeds shown are estimated to be within about +/-5% accuracy, and wind power density values (which are related to the cube of the speed) are estimated to be within about +/-15% accuracy. This means that the actual wind speed should be within 5% of the predicted at two-thirds of the locations on the map, and should be within 10% of the actual at about 95% of the locations, assuming that the measurements are taken in well exposed areas, with minimal obstructions, and following wind industry measurement guidelines. The two models work together, but at different scales. MASS operates on a spatial grid resolution of 2.6 km (1.6 miles), whereas WindMap operates on a resolution of 400 meters (1312 ft, or one-quarter mile), which is the final scale of the maps. While WindMap can simulate the acceleration of winds over small hills and ridges, many other terrain effects require the more sophisticated MASS. Such effects include channeling through valleys or passes (such as Judith Gap or Livingston Pass) and downslope flows (e.g., Blackfeet area). To the extent these effects are at work, the accuracy of the maps is limited by the spatial grid resolution of MASS. To be resolved completely, a terrain feature must be larger than about 3-4 grid cells. Therefore, for instance, a valley that is less than about 7-10 km wide will not be fully "seen" by the MASS model, and if there is any channeling through that gap, it will be underestimated or entirely missed in the map. Likewise, detailed aspects of a downslope flow, including its intensity and full extent, will not be resolved better than the scale of the MASS simulations. Site feasibility studies should be conducted to confirm the map estimates, including direct measurement at turbine hub height according to wind energy industry standards. Weather deviations from long-term averages and local terrain effects may cause additional variations from the map estimates. Local site characteristics such as trees, buildings and other obstructions can significantly affect wind speed and turbine output estimates. Wind speeds can be reduced at up to four times the height of an obstruction and as far away as a mile or more. Small differences in wind speeds translate into large differences in turbine outputs. Neither TrueWind Solutions nor any of the project sponsors (including NREL, BPA, Northwest SEED and NWCDC) make any guarantees or accept liability for the accuracy of the estimates presented here. Use of the maps and/or data for anything other than general information is solely at the risk of the user. TrueWind and project sponsors may not be held liable for any loss, damage or other consequence resulting form the use of the maps and/or data contained on these pages. Please see Adjustments for Local Conditions and Accuracy of Wind Map Estimates for more information. By using this data, the user agrees that he or she has read the disclaimer statement above and agrees to assume all liability for using the data.
Data Access
Distributor Montana State Library
PO Box 201800
Helena, MT 59620-1800
Telephone: 406-444-5354
TDD/TTY: Montana Relay 711
Fax: 406-444-0266
Distribution liability The Montana State Library provides this product/service for informational purposes only. The Library did not produce it for, nor is it suitable for legal, engineering, or surveying purposes. Consumers of this information should review or consult the primary data and information sources to ascertain the viability of the information for their purposes. The Library provides these data in good faith but does not represent or warrant its accuracy, adequacy, or completeness. In no event shall the Library be liable for any incorrect results or analysis; any direct, indirect, special, or consequential damages to any party; or any lost profits arising out of or in connection with the use or the inability to use the data or the services provided. The Library makes these data and services available as a convenience to the public, and for no other purpose. The Library reserves the right to change or revise published data and/or services at any time.
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Metadata date 12/19/2013

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