MesoMap
MesoMap® provides accurate, reliable, and affordable wind
data. MesoMap assesses wind resources over large regions at a high resolution
(typically 200 m, or 10 acres) using a combination of mesoscale and microscale
models and weather data. It has been proven effective, even in complex terrain
and wind regimes, in over 50 countries throughout the world. Wind maps and
atlases have been produced for Southeast Asia, Brazil, China,
Canada, India, the United States,
Great Britain, Ireland, Poland, and many other countries
and regions. Independent validation with data from over 1000 stations worldwide
has established a typical accuracy range of 5-7% in mean speed at hub height.
Value
Until recently, the only way to evaluate the wind energy
potential over a large area and to identify attractive sites for wind projects was
to travel around with topographic maps, find some promising spots, and take measurements—a
costly, time-consuming process that often leaves large gaps in knowledge. With
MesoMap, this task is accomplished quickly and systematically. Governments can
determine how much wind energy may contribute to their future energy supplies
and plan wind monitoring campaigns more effectively. Project developers can
quickly focus their attention on potential sites before any measurements are
taken.
MesoMap does not make conventional wind resource assessment techniques obsolete, but it reduces their cost and multiplies their effectiveness. MesoMap’s unique benefits include:
- Produces reliable results without surface wind measurements (although where available, such data are used to validate and refine the maps).
- Handles complex wind conditions beyond the capability of most models, such as katabatic mountain winds, channeling through mountain passes, lake and sea breezes, low-level jets, and temperature inversions.
- Directly simulates long-term wind conditions, thereby eliminating the need for uncertain climatological adjustments of short-term data.
- Widely tested and validated, more so than any other wind mapping system in use today.
Technology
MesoMap combines the strengths of two models: a mesoscale
weather model (presently MASS) and a microscale wind flow model (presently
WindMap). As a model developer–not just a user–AWS Truewind is continually
improving and updating its models to achieve the best possible performance.
MASS (Mesoscale Atmospheric Simulation System) is a non-hydrostatic numerical weather model developed by AWS Truewind's partner, MESO, Inc. It is similar to other well-known mesoscale models such as MM5 but has been specifically adapted to wind resource assessment. Run in a series of nested grids, MASS establishes the general patterns of wind and weather in a region down to a scale of 1 to 3 km. These patterns reflect the influence of terrain, vegetation, oceans and lakes, solar heating, radiative cooling, convection, and many other factors. The key meteorological inputs to MASS are reanalysis and rawinsonde data, which provide a snapshot of atmospheric conditions at regular time intervals throughout the world over the past several decades. Taking these data as a starting point, MASS simulates the evolution of the atmosphere over 366 days sampled from a 15-year historical period. The sampling method gives the correct weight to different seasons while providing a statistical accuracy in the mean annual speed of 2 to 3%.
The MASS output is then used to drive WindMap, a
mass-conserving wind flow model. WindMap sharpens the picture created by MASS
to account for the localized effects of terrain and surface roughness
variations. It produces wind flow spatial resolutions of 200 m or finer. When the
runs are finished, the results are compiled to produce maps of mean wind speed
and wind power density as well as data bases containing wind speed and direction
distributions.
In the final stage of the mapping process, the maps are compared with wind data from monitoring sites in the region (if available). Depending on the results of this analysis, adjustments may be made to the maps.
Accuracy
The accuracy of the MesoMap system has been verified by
comparing map predictions with independent observations for over 1000 stations around
the world. This validation program is by far the most extensive ever carried
out for a wind mapping system. The US National Renewable Energy Laboratory has
been closely involved.
In open plains and well offshore, the root-mean-square
(rms) error has typically been found to be 5% or less. In more complex regimes, such as coastal mountain passes,
the rms error is typically 0.3–0.5 m/s, or 5–7% of the mean speed. This is comparable
to the error margin associated with one year of measurement from a 50-m mast.
Although extremely effective for mapping large areas and selecting promising project sites, MesoMap does not, of course, produce perfect results. The leading sources of error are the grid resolution of the mesoscale and microscale runs; uncertainty in land cover and surface roughness; and sparse meteorological data in some developing countries. For clients with more demanding accuracy requirements on a smaller scale, these challenges can be met by AWS Truewind’s SiteWind™ system, which employs higher resolution in both the mesoscale and microscale models and uses site data directly in the mapping process to improve accuracy.