Radar Precipitation Echoes Experiments on Temporal, Spatial, and Frequency Correlation

This paper summarizes measurements of the characteristics of precipitation clutter. The goal was to provide for the radar engineer a description of the spectrum, the spatial uniformity, and the frequency correlation properties of precipitation echoes. These experiments resulted in a more complete description of the clutter characteristics than has heretofore been available. The wind shear phenomenon was found to have a dominant effect on the spectra at distant ranges. An analytical model for the spectral width is suggested. Other results show that the mean backscatter cross section is rarely uniform in space and that the frequency correlation characteristics confirm the theory predicting that echoes from pulses separated in frequency by at least the reciprocal of the pulse width are uncorrelated.