Exploring the statistical characteristics of coastal winter precipitation measured using a Parsivel2 disdrometer: A case study in North Carolina

A drop size distribution (DSD) of a precipitation event is a key characteristic and plays a critical role in quantitative precipitation estimation. In this study, DSD datasets were collected by a Parsivel(2) disdrometer in Elizabeth City, North Carolina, U.S. from October 2021 to April 2022. The microphysical and statistical characteristics of the DSD were examined. For this period, the contribution of small raindrops (< 1 mm) to the total number concentration (Nt) was the largest, while the contribution of large raindrops (3-8 mm) to Nt was the smallest. As expected, large raindrops had the largest impact on rain rate (R), liquid water content (W), and radar reflectivity factor (Z), while small raindrops had the least. The shape of the averaged DSDs was similar for different rain rates while the width of the raindrop concentration spectrum increased as rain rates increased. The average mass-weighted diameter D-m (log(10)N(w), generalized intercept parameter) value for all rain events was found to be 1.11 mm (4.54), while for stratiform rains D-m was 1.18 mm (4.65), and for convective rains, it was 0.89 mm (4.17). The empirical relationships between rain intercept parameter (N-0) vs shape factor (mu), mu vs slope factor (Lambda), log(10)N(w) vs median volume diameter (D-0), D-0 vs R, R vs kinetic energy (KE), and Z-R relationship were also derived. These findings are useful for design of rainfall simulators and for better understanding erosive properties of rainfall that contribute to contaminant fate and transport.