From AMS Glossary
In radar, a series of consecutive scans, either around the horizon or in a sector, that together sweep out a volume of space.
Volume scans are typically performed by conducting a series of horizontal scans, each at a progressively higher elevation angle. A less common method is to conduct a series of vertical scans between the horizon and the zenith, each at a different azimuth angle. Volume scans are used to develop three-dimensional views of the reflectivity field and, in the case of a Doppler radar, the radial velocity field associated with the targets illuminated by the radar.