An atmospheric river affecting Australia and the Southern Ocean on 28–29 January 2018 during the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES) is analyzed using nadir‐pointing W‐band cloud radar measurements and in situ microphysical measurements from a Gulfstream‐V aircraft. The AR had a two‐band structure, with the westernmost band associated with a cold frontal boundary. The bands were primarily stratiform with distinct radar bright banding. The microphysical evolution of precipitation is described in the context of the tropical‐ and midlatitude‐sourced moisture zones above and below the 0°C isotherm, respectively, identified in Part I. In the tropical‐sourced moisture zone, ice particles at temperatures less than −8°C had concentrations on the order of 10 L⁻¹, with habits characteristic of lower temperatures, while between −8°C and −4°C, an order of magnitude increase in ice particle concentrations was observed, with columnar habits consistent with Hallett‐Mossop secondary ice formation. Ice particles falling though the 0°C level into the midlatitude‐sourced moisture region and melting provided “seed” droplets from which subsequent growth by collision‐coalescence occurred. In this region, raindrops grew to sizes of 3 mm and precipitation rates averaged 16 mm hr⁻¹.

中文翻译：

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澳大利亚和南大洋上的大气河的结构：II。微物理进化

在2018年1月28日至29日进行的南大洋云，辐射，气溶胶传输实验研究（SOCRATES）期间，一条影响澳大利亚和南大洋的大气河流使用了最低点W波段云雷达测量结果和来自湾流的原位微物理测量结果进行了分析-V飞机。AR具有两波段结构，最西端的波段与冷锋边界相关。这些频带主要是层状的，具有明显的雷达亮带。在第一部分中分别描述了在0°C等温线以上和以下的热带和中纬度水汽带的背景下描述了降水的微物理演化。在热带水汽带中，温度低于-8°C的浓度约为10 L ^-1在-8°C至-4°C之间具有较低温度的习性特征，观察到冰粒浓度增加了一个数量级，柱状习性与Hallett-Mossop次生冰形成一致。冰粒通过0°C落入中纬度水汽区并融化，形成“种子”液滴，随后通过碰撞凝聚而生长。在该区域，雨滴长到3毫米，降水速率平均为16毫米hr ^-1。