Classification of precipitation and volcanic clouds using operational X-band polarimetric radar parameters

Explosive volcanic eruptions are severe natural phenomena that produce pyroclastic materials, eruption columns, and volcanic ash clouds. During moist weather conditions, volcanic eruption products can be coated with water, resulting in wet ash and/or mixtures of ash and rain. Wet ash, which is heavier than dry ash increases the risk of towers and poles collapsing, and rain mixed with volcanic ash is a harmful natural phenomenon that threatens human life, infrastructures, economies, agriculture, etc. Optical measurements, which are made with ground-based instruments (ex, two-dimensional video disdrometer (2DVD), parsivel, etc.), cameras, and satellites, are limited in their ability to detect volcanic ash clouds and eruption columns in cloudy or precipitation conditions. Weather radar is one of the key instruments for studying and monitoring both precipitation and volcanic ash clouds, since it can observe both types of system and can provide valuable information that can discriminate between the two systems through the use of polarimetric parameters. In this paper, our goal is to find characteristic of polarimetric parameters for volcanic ash clouds and precipitation using observed radar data, and to make a classification algorithm for discriminating two systems.爆炸性火山喷发是一种剧烈的自然现象，会产生火山碎屑物质、喷发柱以及火山灰云。在潮湿天气条件下，火山喷发产物会附着水分，形成湿火山灰，或是火山灰与雨水的混合物。湿火山灰比干火山灰更重，会增加塔架和杆塔倒塌的风险；而火山灰与雨水的混合物则是一种有害自然现象，会威胁人类生命、基础设施、经济以及农业等领域。基于地基仪器（例如二维视频雨滴谱仪（two-dimensional video disdrometer，2DVD）、Parsivel等）、相机以及卫星开展的光学测量，在多云或降水条件下检测火山灰云和喷发柱的能力存在局限。气象雷达是研究和监测降水与火山灰云的关键仪器之一，因为它既能观测这两类气象系统，还可通过极化参数提供可区分二者的有效信息。本文旨在利用实测雷达数据，提取火山灰云和降水对应的极化参数特征，并构建用于区分这两类系统的分类算法。