A dopplergraph or dopplergram is a two-dimensional representation of the approaching and receding motions of an object or area. The word "dopplergraph" is a combination of the words doppler and photograph. Dopplergraphs are two-dimensional records of variations in the doppler shift in light intensity.
Dopplergraphs do not need to be a record of the shift of visible light, but of any radiated wave, which includes electromagnetic waves and acoustic waves.[1]
Because the doppler shift is caused by the velocity of the radiating source towards or away from the viewer, a dopplergraph is a picture of the velocities associated with the sources being viewed.