Ghost Echoes

Ghost echoes are returns which are displayed at an incorrect range. This is a failure of the Range Unfolding Algorithm, which is only apparent under a rare combination of conditions. Fortunately, the potential for ghost echoes can be eliminated.

In this example from Lubbock, TX, note that this Reflectivity product was generated in VCP 12 at 1.8 degrees, which is the lowest elevation for Batch Mode. The real echoes are the storms at longer range, with the stronger cells identified as D, E, and F. The associated ghost echoes are closer to the radar with the stronger returns at points A, B, and C. The ghost echoes appear as a result of a failure of the Range Unfolding Algorithm which occurs only when all bins suppression is performed in the Batch mode elevations. The ROC has issued a document with additional information on this potential problem.

Though rare, ghost echoes can occur with any VCP and any recent RPG Build. They are possible under the following conditions:

1. Elevations where Batch mode is employed (1.65 to 6.4 degrees for VCPs 11, 12, 21 and 121)

2. All bins clutter suppression has been applied to these elevations (high segment)

3. When there is significant echo beyond the unambiguous range of the velocity data

The possibility of ghost echoes can be eliminated by only using the bypass map for clutter suppression within the high segment.