THE CLIMATE ADJUSTMENT PROCESS - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 152

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THE CLIMATE ADJUSTMENT
PROCESS
The last major step in characterizing the wind resource at a wind monitoring station,
before extrapolating it to the wind turbine locations, is to adjust the observed wind
climate to the historical norm. Average wind speeds can vary substantially from the
norm even over periods of a year or longer. Typically, the uncertainty in the long-term
mean wind speed based on a year of measurement alone is about 3 - 6%, 1 correspond-
ing to perhaps 5 - 10% in the mean wind plant production — a significant factor when
assessing the risk of financing a wind project. Reducing this uncertainty is the primary
goal of the climate adjustment process.
The leading method for performing climate adjustments is popularly called MCP ,
which stands for measure, correlate, predict. The wind resource is measured at a site
(sometimes called the target ) over a period ranging from several months to several
years. The observed winds at the target site are correlated with those recorded at a
long-term reference, such as an airport weather station, and a relationship between
1 On the basis of an analysis by AWS Truepower of data from first-order meteorological stations in North
America. At some locations, the interannual variability may be larger or smaller than this range.