Building a climatology of precipitation system organization in the Carolinas using the NOAA radar-based Multi-Sensor Precipitation Estimation (MPE) product

This paper presents early results of a novel 5-year climatology of precipitation system organization in the Carolinas. The premise of this NSF-funded study is that a climatology of precipitation system “mode of delivery” will lead to improved regional climate and hydrological forecasts, and provide a unique tool for process-based downscaling of climate simulations. “Mode of delivery” refers to the structural, temporal and water phase characteristics of a precipitation system. Examples of mode of delivery that occur in North Carolina within various synoptic regimes include short duration and spatially heterogeneous convective cells, large mesoscale convective systems, widespread long-lasting frontal precipitation, tropical cyclones, and winter precipitation. Each “mode of delivery” may produce similar time-averaged precipitation totals, but have very different climate and hydrological impacts due to different spatial and temporal distributions of precipitation.

The analysis is based on the NOAA high resolution multi-sensor precipitation estimation (MPE) dataset, extracting a portion of the NMQ Q2 national radar reflectivity three-dimensional mosaic centered on North Carolina to identify and analyze precipitation systems. We will illustrate our approach by contrasting two 5-day periods representing summer and winter regimes. For each, all near-surface rainfall features > 0.1 mm/hr are identified and segregated into size categories, which determine whether or not each is associated with a mesoscale convective system. Within these features, rainfall is divided into convective vs. stratiform portions, frozen vs. liquid precipitation, and shallow (warm) rain. The duration of each precipitation type at each pixel is tracked and integrated over hourly, daily and weekly time periods. Finally, frequency distributions of feature area, maximum length, echo top height, and the various rainfall types are determined on daily and weekly timescales.