OFFSHORE RESOURCE ASSESSMENT - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 215

SAR is mapping wakes from operating offshore wind projects. The extent of wake
influences offshore is an important issue, as very large wind projects are planned in
areas such as the North Sea, and realistic wake simulations remain a difficult challenge
for numerical models.
In interpreting wind speeds derived from all satellite-based microwave sensors, it
is important to keep the following in mind:
• Microwave sensors cannot retrieve wind speeds when the sea surface is covered
by ice, which means that for some parts of the world, the winter season can be
underrepresented in the image or data sample.
• The wind speeds represent spatial averages over the sensor's effective resolution
for a particular moment in time, whereas anemometers and surface-based remote
sensing systems typically measure time-averaged winds for a specific point. This
difference means that satellite-based measurements rarely match surface-based
measurements exactly.
• Most satellites are in polar orbits that take them over the same location at specific
times each day. For instance, the QuikSCAT satellite passed twice daily over
Eastern Canada at approximately 10:00 UTC and 22:00 UTC. It is, therefore,
not possible to obtain the full diurnal cycle of wind speeds from those satellites.
Fortunately, the diurnal pattern of wind speed variation offshore is usually much
less than it is on land, and therefore, the errors introduced by this limited sampling
are generally minor.
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