Impact of WSR-88D MESO-SAILS Usage on MRMS-Based Quantitative Precipitation Estimation

Quantitative precipitation estimation (QPE) is a critical aspect of the United States' operational Weather Surveillance Radar 1988-Doppler (WSR-88D) network. By estimating QPE accurately, radar data can be fed into hydrological models to provide near-real time flash flood guidance to forecasters issuing life-saving warnings. Among the most commonly used tools by forecasters are the Multi-Radar Multi-Sensor (MRMS) QPE products, which utilize WSR-88D data to re-process QPE as a mosaic that is corrected by ground-based rain gauges. As part of ongoing WSR-88D upgrades, enhancements, and service-life extension plans, the National Weather Service (NWS) Radar Operations Center (ROC) regularly adds new Volume Coverage Pattern (VCP) options to the network. In the past decade, this has included the option for supplemental adaptive intra-volume low-level scans (SAILS), as well as the multiple elevation scan option for SAILS (MESO-SAILS). SAILS and MESO-SAILS allow radar operators to insert between one and three additional base tilt(s) evenly spaced throughout a VCP. It is shown in this study that since the MRMS QPE initial inputs are derived from WSR-88D Level-II estimates, and additional base scans at higher temporal resolution decreases the integration period for QPE, errors in QPE decrease as the number of SAILS scans increases. Presentation of statistically quantified results are supported by a discussion of the applicability to future weather radar networks such as phased array radar systems.