Motion of echo structures observed with volume imaging atmospheric radar

Volume imaging radar often shows echo patterns on horizontal scale ∼100–1000m, moving across the radar. The echoes could be from convection, and moving at near the background wind velocity; other explanations are clouds or regions of turbulence. This paper studies the motion of echoes, with a two-dimensional correlation method widely used for cloud motion winds and tracking weather radar echoes, but not applied before to wind profiling radar. Data are from the MU (middle and upper atmosphere) radar, Japan. Several factors causing an underreading of echo speed are removed; however, remaining data still show echoes moving a few ms-1 slower than the background wind, with similar direction. This could be explained by convection, consistent also with some increased vertical-beam spectral width showing turbulence. Motion of convective echoes slower than the background wind could bias other radar wind measurements.