OVERVIEW OF A WIND RESOURCE ASSESSMENT CAMPAIGN - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 19

2.3.3 Estimating the Hub Height Resource
Since meteorological towers are often shorter than a turbine's hub height (the center
of the rotor), where its power curve is defined, it is often necessary to extrapolate
speed measurements between heights. This task requires a careful and often subjective
analysis of information about the mast and site, including the observed shear, local
meteorology, topography, and land cover. The information in Chapter 11 helps guide
the analyst through this process.
2.3.4 Climate Adjustment
The objective of climate adjustment is to correct measurements taken over a
limited period to long-term historical conditions. This is important because wind
speeds can vary substantially from the norm even over a period of a year or longer.
A process known as measure, correlate, predict (MCP) is typically used to relate and
adjust on-site measurements to a long-term reference. This reduces the uncertainty
in energy production estimates. Chapter 12 provides an overview of the MCP
process.
2.3.5 Wind Flow Modeling
Since on-site wind measurements are usually limited to just a few locations within
a project area, wind flow modeling, most often done with computer software, must
ordinarily be used to estimate the wind resource at all locations where wind turbines
might be deployed. Chapter 13 provides an overview of the types of wind flow models
that are available, their inputs and appropriate applications, and the uncertainties and
challenges associated with them.
2.3.6 Uncertainty in Wind Resource Assessment
A sound understanding of the uncertainty associated with the wind resource assessment
process is necessary for project financing. Chapter 15 reviews the potential sources
of uncertainty and how they are estimated and provides typical ranges of uncertainty
values.
2.3.7 Project Design and Energy Production
The last stage is to design the project and estimate its energy production. This often
complicated process is usually performed with specialized software, which, starting
from the results of the numerical wind flow modeling, allows the user to rapidly test
different turbine layouts and to arrive at one that maximizes energy production. The
software also calculates losses resulting from the wakes cast by turbines. Chapter
16 provides an overview of the project design and energy production estimation
process.