Scintillation is a fluctuation in the amplitude of a target on a radar display. It is closely related to target glint, or wander, an apparent displacement of the target from its mean position. This effect can be caused by a shift of the effective reflection point on the target, but has other causes as well. The fluctuations can be slow (scan-to-scan) or rapid (pulse-to-pulse).
It appears especially at seaside level.
Scintillation and glint are actually two manifestations of the same phenomenon and are most properly linked to one another in target modeling.
References
Scintillation (radar) Wikipedia(Text) CC BY-SA