Using Simulated Radar Data to Determine the Effects of Volume Coverage Patterns on MRMS Products

The implementation of two adaptive intra-volume scanning options in volume coverage patterns (VCP) 12 and 212 named the Supplemental Adaptive Intra-Volume Low-Level Scan (SAILS) and the Mid-Volume Rescan of Low-Level Elevations (MRLE) recently have enhanced the low-level temporal resolution of the weather surveillance radar 88 Doppler (WSR-88D). These adaptive scanning strategies increase the revisit time of the low-level radar elevation angles, but concurrently can decrease the revisit time on the mid- and upper-level elevation angles by several minutes. Furthermore, these new scanning strategies give National Weather Service offices additional choices to consider when determining which VCP to run, resulting in neighboring WSR-88D sites running different VCPs during weather events. When these radar volumes are ingested into the Multiple-Radar Multiple-Sensor (MRMS) framework, the increased low-level scanning frequency could affect many MRMS algorithms that rely on adequate volumetric sampling of a thunderstorm. Yet, such an analysis to determine the extent of these potential errors has yet to be performed.

High-resolution idealized simulations using CM1 were conducted simulating different thunderstorm convective modes. The model output is then decomposed to create synthetic WSR-88Ds observations using different VCPs and intra-volume options at different ranges and locations to the precipitation echoes. These synthetic observations are then merged into the MRMS system to investigate how these intra-volume options are sampling the simulated storm and the effects these VCP differences have on altering the downstream MRMS products.. This presentation highlights the positive and negative effects of these adaptive intra-volume options on the MRMS system, including storm coverage by WSR-88D, vertically derived products, and new challenges created by adaptive VCPs utilized during convective events.