Renewable Energy Center

How Wind Maps Are Created (and how accurate are they?)

Our version. . .really smart folks take a lot of weather data from US Wind Map
a lot of places and feed into really complicated mathematical models that actually turn out to be pretty accurate estimators of on-the-ground conditions.

If our answer doesn't satisfy you, here's what the wind modeling experts at companies like AWS Truewind, 3Tier and
WindLogics say (the following is from AWS Truewind's website www.awstruewind.com):

How are wind maps created? What data sources are used? How accurate are they?

"Wind modeling companies use mesoscale and microscale atmospheric models. The mesoscale model simulates weather conditions for a representative meteorological year (366 days sampled from 15 years) on a horizontal grid of 2.5 km. Starting from an initial condition established by regional weather data, and using the complete set of physical equations governing the atmosphere, the model simulates the evolution of weather conditions from the start to end of each day in the year. The microscale model then refines the wind fields from the mesoscale model to capture the influence of fine-scale topography and surface roughness changes at a high resolution of 200 m.

The maps have subsequently been fine-tuned through an error-correction procedure developed by AWS Truewind, which uses data from over 1000 wind-monitoring stations from public and authorized private sources."

What data sources are used?

"Incorporated in the initial conditions for the mesoscale simulations are weather observations from many thousands of platforms, including surface stations, instrumented balloons, satellites, aircraft, and others. These data have been assimilated into the NCAR/NCEP Global Reanalysis (NNGR) database, which provide a snapshot of weather conditions every 6 hours on a 2.5 degree resolution grid for nearly the past 60 years. Data from rawinsonde stations (instrumented balloons), as well as sea-surface temperatures, land cover, topography, and other geophysical data, also drive the simulations.

The error-correction procedure relies on data from over 1,000 wind-monitoring stations in AWS Truewind's windObs Database. The data have all been carefully screened, adjusted to represent historical average wind conditions where appropriate, and projected to the map height using a measured or estimated wind shear factor."

How accurate are the wind maps?

"To produce a true estimate of the map error margin, each station in AWS Truewind's database was withheld from the error-correction procedure and the map error (difference between the map speed and the observed speed) at that station was determined.

The standard error (after accounting for uncertainty in the data) is about 0.35 - 0.75 meters per second depending on the resolution. See the chart below for a scatter plot comparing the predicted mean wind speeds with the observed after projection to the same map height."

MapAccuracyChart

Source: AWS Truewind www.awstruewind.com

AWS Truewind's WindNavigator tool can also help you take a look at your wind resource
along with 3Tier's FirstLook tool, another wind modeling company.

AWS Truewind invites others to donate data as well for future map updates.

Saint Francis University