This panel shows an example of how wind speed and the radar return ("sigma0" on the left axis) are related for a variety of angles between the satellite and the sea surface.  Low returns (low sigma0) occur at low wind speeds.  High returns (high sigma0) occur at high wind speeds.  This wind speed model function is calibrated by comparing with independent measurements of ocean winds from ships or ocean buoys.

• Are wind measurements more accurate at large or small incidence angles?

    Large incidence angles.   For small incidence angles, such as 10 degrees,
    a small range of sigma0 corresponds to a large range of wind speeds.  In
    this case, sigma0 must be measured very precisely to obtain an accurate
    wind measurement.  For larger incidence angles, a large range of sigma0
    corresponds to a large range of wind speeds and a less precise sigma0
    measurement can produce an accurate wind measurement.

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