The accuracy of rainfall estimates by radar as a function of range

High-spatial-resolution data were collected for nearby convective storms by using a volume scanning weather radar with 200m resolution, and for stratiform events by using a high-resolution (20m) vertically pointing radar. Errors in the estimation of rainfall by the scanning radar, due to the radar beam intersecting or overshooting features such as the bright band, were simulated by using these high-resolution images. It was found that these effects define a maximum useful range for the radar that is a strong function of the prevailing meteorological conditions (e.g. bright-band height, intense cell diameter and height). Sudden changes in bright-band height over short times and the large scatter observed in its thickness limit the accuracy with which corrections for the vertical profile of reflectivity may be precalculated in stratiform rain events. A scheme for using a vertically pointing radar to produce these corrections in real time is proposed. the convective events show enough significant storm-to-storm variability that caution is required in extending the useful range of the radar too far.