The Role of WSR-88D VCPs and Intra-Volume Scanning Strategies on Volumetric Analyses of Thunderstorm Intensity using Simulated Observations

Changes to volume coverage patterns (VCPs) to allow intra-volume scans of the lowest tilt has been implemented on the WSR-88D network. Additionally, a new precipitation VCP is being added that blends the best attributes of three precipitation VCPs (11, 12, 21). This new VCP named 215 combines the low level scanning strategy of VCP 12, the upper level scanning strategy of VCP 11, and the improved data quality of VCP 21. VCP 215 also allows for one additional intra-volume scan of 0.5 degrees. This new VCP and intra-volume scanning parameters increase the frequency of low level scans which aid in the more rapid detection of tornadic and low level wind signatures. However, the trade off is a slower update time in the mid and upper levels of the atmosphere by upwards of 90 seconds. This added latency has the potential to affect performance of vertically derived products in the Multiple-Radar Multiple-Sensor (MRMS) system. Potentially any algorithm that relies on timely volumetric sampling of precipitation may be affected.

To investigate the potential impact of these changes to the WSR-88D network, high-resolution idealized simulations using CM1 were conducted simulating a fast and slow moving supercell. The model output is decomposed to create synthetic WSR-88D observations using different VCPs and intra-volume options at various ranges to the precipitation echoes. The radar ranges to the storm are based on the mean distance of any location to the nearest four radars across three regions of the United States (e.g. East, Central, and West). These synthetic observations are then merged into the MRMS system to investigate how these new VCP options are sampling the simulated storm and the effects these VCP differences have on altering the downstream MRMS products. This presentation highlights the strengths and limitations 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.