What is Range Folding (RF)? What does the purple color mean?
Sample radar image with range folded regionsRange Folding is basically when the radar is unable to determine the wind’s velocity. This is due to the speed at which the radar transmits signals, called the pulse repetition frequency (PRF). The faster the pulses are sent by the radar the less time it has to listen for any returned signals. It occurs when the return from a prior pulse is detected during the listening period for the current pulse. Both reflectivity and velocity data are affected by this. The occurrence of range folding can usually be detected by radar software and reflectivity data can be “unfolded” using special programs. However, velocity data cannot be accurately unfolded and therefore the effective range with which Doppler radars can detect velocity data is limited by the frequency of the radar pulses; the higher the pulse rate, the shorter the range within which the velocity field can be determined.
