"Ground clutter" occurs when radar side-lobes bounce off objects and the ground in the vicinity of the radar. Most of the ground clutter echoes are stationary (since objects on the ground are not moving) and can be filtered out by NEXRAD "declutter" algorithms so it is not seen by users. However, there are always some echoes which do not have coherence from one scan to the next which show up even though the declutter algorithm is being applied. Much of it may be insects or other close-in scatterers as well as actual echoes from the ground.
Therefore, ground clutter has a different appearance than precipitation echoes which are contiguous and have spatial coherence. Ground clutter usually has a somewhat speckled appearance and changes from scan to scan.
Most sites being shown in this figure are displaying ground clutter. The echoes in central Oklahoma are anomalous propagation.
Ground clutter usually shows up more strongly in clear-air mode than in precipitation mode, because clear-air mode is a more sensitive level of operation. The following radar is operating in VCP 35, the newest clear air mode VCP, and shows ground clutter around the radar location.
