The seeder–feeder interactions (SFIs), where raindrops from upper clouds grow by accreting cloud droplets in the lower clouds, have been extensively studied. However, there are few studies on the modification of raindrop size distribution (DSD) through this process. In the present study, rainfall from the landfalling rainbands of a typhoon was observed using an optical disdrometer and an X-band polarimetric radar. Rainfall was classified into the following three types based on the DSD characteristics at the surface and the existence of a ρ_HV minimum in the upper layer: convective rainfall accompanied by a melting layer (type SF), convective rainfall without a melting layer (type C), and stratiform rainfall with a melting layer (type S). Type SF rainfall was regarded as having undergone SFIs between stratiform precipitation and shallow convection. The DSD for SF type rainfall was characterized by more small- to medium-sized raindrops and a larger normalized intercept parameter than rainfall types C and S. An analysis using vertical profiles of radar-derived DSD parameters for type SF rainfall suggested that the median-volume diameter of raindrops increased by accreting cloud droplets in the lower clouds, and that small- to medium-sized raindrops were produced by a warm rain process and breakup of raindrops.

中文翻译：

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X波段极化雷达和光学偏差计观测到的层状降水和浅对流之间的种子-馈线相互作用导致雨滴尺寸分布的修正

来自上层云的雨滴通过在下层云中吸积云滴而生长的播种机-馈线相互作用 (SFI) 已被广泛研究。然而，很少有关于通过该过程修改雨滴尺寸分布（DSD）的研究。在本研究中，使用光学偏差计和 X 波段极化雷达观测来自台风登陆雨带的降雨。根据地表 DSD 特征和ρ _HV的存在，降雨分为以下三种类型上层极小值：有融层的对流降雨（SF型），无融层的对流降雨（C型），有融层的层状降雨（S型）。SF 型降雨被认为在层状降水和浅层对流之间经历了 SFI。与降雨类型 C 和 S 相比，SF 型降雨的 DSD 具有更多的中小型雨滴和更大的归一化截距参数。使用雷达衍生的 SF 降雨的 DSD 参数的垂直剖面分析表明，中值雨滴体积直径因低层云滴的增加而增大，而中小雨滴则是由暖雨过程和雨滴分解产生的。