Hurricane rainbands are very efficient rain producers, but details on drop size distributions are still lacking. This study focuses on the rainbands of hurricane Dorian as they traversed the densely instrumented NASA precipitation-research facility at Wallops Island, VA, over a period of 8 h. Drop size distribution (DSD) was measured using a high-resolution meteorological particle spectrometer (MPS) and 2D video disdrometer, both located inside a double-fence wind shield. The shape of the DSD was examined using double-moment normalization, and compared with similar shapes from semiarid and subtropical sites. Dorian rainbands had a superexponential shape at small normalized diameter values similar to those of the other sites. NASA’s S-band polarimetric radar performed range height-indicator (RHI) scans over the disdrometer site, showing some remarkable signatures in the melting layer (bright-band reflectivity peaks of 55 dBZ, a dip in the copolar correlation to 0.85 indicative of 12–15 mm wet snow, and a staggering reflectivity gradient above the 0 °C level of –10 dB/km, indicative of heavy aggregation). In the rain layer at heights < 2.5 km, polarimetric signatures indicated drop break-up as the dominant process, but drops as large as 5 mm were detected during the intense bright-band period.

中文翻译：

---

NASA Wallops降水研究设施的Dorian飓风外雨带的液滴尺寸分布测量

飓风雨带是非常有效的雨水产生者，但仍缺乏有关雨滴大小分布的细节。这项研究着重研究了多利安飓风的雨带，历时8小时，它们穿过弗吉尼亚州瓦洛普斯岛密密麻麻的NASA降水研究设施。液滴尺寸分布（DSD）使用高分辨率气象颗粒光谱仪（MPS）和2D视频测速仪进行测量，二者均位于双栅栏挡风玻璃内。使用双矩归一化检查DSD的形状，并与来自半干旱和亚热带地区的相似形状进行比较。多里安雨带在与其他站点相似的较小归一化直径值下具有超指数形状。美国国家航空航天局（NASA）的S波段极化雷达执行的测距高度指示器（RHI）扫描了整个测速仪站点，在融化层中显示出一些显着的特征（亮带反射率峰值为55 dBZ，共极相关性下降到0.85，表明有12–15 mm的积雪，以及0°C时–10 dB之上的惊人的反射率梯度/ km，表示严重聚集）。在高度小于2.5 km的雨层中，极化特征表明液滴破裂是主要过程，但在强烈的亮带时期可检测到最大5 mm的液滴。