Development for measurement of physical characteristics of falling snowflake and its application to radio wave attenuation

落雪物理特性测量及其在无线电波衰减中的应用的开发

• 批准号: 09555124
• 负责人: MURAMOTO Ken-ichiro
• 金额: $ 4.74万
• 依托单位: Kanazawa University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09555124/
• 关键词: image processing; snowflake; falling pattern; size distribution; snowfall rate; radar reflectivity factor; radio wave attenuation; 降雪電波反射特性

It is thought that snowflakes grow by the collision and adhesion of snowflake crystals during their fall. This growing process is effected by shape and falling motion of snowflake. It is not only important in consideration relating to the cloud physics, but also for various engineering applications such as remote sensing and telecommunications and lately in the field of global climate monitoring. Precipitation phenomena play an important part in fields related to radio wave attenuation and propagation. In the study of precipitation, one of the main instrument used is the radar. Radar measurements of precipitation are based on the relation between the radar reflectivity factor Z and precipitation rate R. In order to determine the Z-R relationship for snowfall, Z and R have to be measured independently with high accuracy at short time intervals. However, few systems have been developed for measurement of snowfall rate with high degree of accuracy and temporal resolution.In order to measure the physical parameter of snowflakes, natural falling snowflakes were photographed by TV cameras. The diameter, velocity and density of each snow particle were computed from these images. Snowfall rates calculated from image data are computed with values directly obtained using an electronic balance. During this observation, the received power was measured using a small X-band Doppler radar. The relationship between X-band wave attenuation and snowfall rate was investigated and compared to the physical characteristics of snow particles. It was suggested that the power spectrum was related with the density of snow particles.

人们认为雪花是在下落过程中通过雪花晶体的碰撞和粘附而生长的。这个生长过程受雪花的形状和下落运动的影响。它不仅在与云物理有关的考虑中是重要的，而且对于各种工程应用，如遥感和电信以及最近在全球气候监测领域中也是重要的。降水现象在无线电波衰减和传播相关领域中起着重要作用。在降水研究中，雷达是主要的仪器之一。雷达测量降水是根据雷达反射率因子Z和降水率R之间的关系。为了确定降雪的Z-R关系，必须在短时间间隔内独立地测量Z和R。然而，目前还没有开发出高精度和高时间分辨率的降雪率测量系统，为了测量雪花的物理参数，人们用电视摄像机拍摄了自然飘落的雪花。每个雪颗粒的直径、速度和密度都是从这些图像中计算出来的。根据图像数据计算的降雪率是使用电子天平直接获得的值计算的。在这次观测中，使用小型X波段多普勒雷达测量接收功率。研究了X波段波衰减与降雪率之间的关系，并与雪粒子的物理特性进行了比较。结果表明，功率谱与雪粒子的密度有关。

项目成果

H. Servomaa, T. Shiina, K. Muramoto, T. Harimaya: "Experimental determination of a Z-R relation for snowfall and its evaluation by shape characteristics."Technical Report of IEICE. AP98-99. 49-54 (1998)

H. Servomaa、T. Shiina、K. Muramoto、T. Harimaya：“降雪 Z-R 关系的实验测定及其形状特征的评估。”IEICE 的技术报告。

T. Harimaya, T. Sawada, N. Kanemura: "Regional characteristics of the riming growth process."Geophysical Bulletin of Hokkaido University, Sapporo, Japan. No. 62. 1-13 (1999)

T. Harimaya、T. Sawada、N. Kanemura：“雾凇生长过程的区域特征。”日本札幌北海道大学地球物理通报。

H. Servomaa, T. Shiina, K. Muramoto: "Radar measurement of snowfall and its evaluation by shape characteristics."Abst. 16th Int. Union of Radio Science. 343 (1999)

H. Servomaa、T. Shiina、K. Muramoto：“降雪的雷达测量及其形状特征的评估。”摘要。

H. Servomaa, K. Muramoto and T. Shiina: "Snowfall rate determined by image processing"Abst. 16th Int. Union of Radio Science. 382 (1999)

H. Servomaa、K. Muramoto 和 T. Shiina：“通过图像处理确定降雪率”摘要。

播磨屋敏生、沢田敏隆、金村直俊: "降雪粒子の雲粒捕捉成長過程の地域特性"北海道大学地球物理学研究報告. 62. 1-13 (1999)

Toshio Harimaya、Toshitaka Sawada、Naotoshi Kanemura：“云捕获雪颗粒生长过程的区域特征”北海道大学地球物理研究报告 62. 1-13 (1999)。