A simple Procedure to Build Instantaneous Polar Volumes from Time-Sampled Multiple Elevation Sweeps

This is a long-standing problem in radar sampling of precipitation volume. Typical volume scans take about 5 minutes to complete, but we also know that convective systems move at speeds of the order of 50 to even 100 km per hour. However, it is common practice to construct a 3D picture stacking these multiple elevation PPIs, sampled about 5 minutes apart. In various applications, radar observations from volume scans need to be compared with other data, such as observations from vertically pointing profilers, downward looking satellite observations, or numerical model outputs. Typically, the observation time for the radar volume scan is considered to be the nominal time (e.g., the scan start time), overlooking the fact that different sweeps within the volume are collected at different times, spanning several minutes. To effectively compare this data with observations collected over a much shorter time frame (e.g., a vertical profile), it is crucial to adjust for the displacement of precipitation relative to the reference time, in particular for systems subject to moderate to strong advection. By analyzing subsequent radar observations to compute motion vectors, we can synchronize the radar data, allowing us to treat the three-dimensional volume information as though it were collected instantaneously. In this work, we present a straightforward method for correcting radar observations in the polar domain, including example applications (e.g. comparison between vertical cuts extracted from a polar volume and profiler observations) and error estimation.