A non-uniform Vertical Profile of Reflectivity (VPR) is an important source of error. For precipitation accumulation products, gauge adjustement cannot correct all VPR effects.

VPR correction schemes include estimation of VPR using 3D radar reflectivity data, NWP output, satellite data, etc. and extrapolation of reflectivity measured at a given altitude to ground level using estimated VPR. VPR profiles vary significantly both spatially and temporally.