THE SPATIAL-TEMPORAL STATISTICS OF RAIN RATE RANDOM FIELDS
THE SPATIAL-TEMPORAL STATISTICS OF RAIN RATE RANDOM FIELDS
复制标题
降雨率随机场的时空统计
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
K. Paulson
中科院分区：
文献类型：
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作者：
K. Paulson
简称：降雨的时空统计。摘要近地面雨量可以解释为随机变量的集合，形成一个由三个坐标参数化的随机场：两个空间坐标和一个时间坐标。无线电传播界的兴趣主要集中在这些随机变量的一阶统计量上，主要是雨率作为位置函数的年平均概率分布。然而，人们越来越感兴趣的是描述高分辨率雨率在时间和空间上的变化的二阶统计量。该信息对于衰落对策的设计和有效的频谱管理是重要的。本文利用2001年1月5日英国东南部一次大范围、慢速移动、强对流降水过程的雷达资料，计算了对数雨率时空变化的二阶统计量。结果表明，原木降雨率在三个坐标下都是自相似的，且时空变化具有对称性。这些数据被用来建立一个各向同性的时空对数雨率模型，假设对数雨率是一个均匀的高斯随机场。该模型被进一步发展，以给出相关雨率、比衰减和对数比衰减随机场的二阶统计量的闭合形式表达式。此外，建立了无线电链路对经历的雨衰减的时间协方差的表达式，并用来自实验链路的测量的雨衰减数据对这些表达式进行了检验。
Short Title: Spatial-Temporal Statistics of Rain. Abstract Rain rate near the ground can be interpreted as a collection of random variables forming a random field parameterised by three coordinates: two spatial coordinates and one temporal. Interest among the radio propagation community has been focused on the first order statistics of these random variables, principally on the average annual probability distribution of rain rate as a function of location. However, increasingly interest is turning to second order statistics describing high-resolution rain rate variation in both time and space. This information is important for the design of fade countermeasures and for efficient spectrum management. In this paper radar data from a wide spread, slow moving and intense, convective rain event experienced by the South Eastern UK on 1/5/2001 are used to calculate the second order statistics of spatial-temporal log rain rate variation. It is demonstrated that log rain rate is self-similar in all three coordinates and that symmetry exists between the spatial and temporal variation. These data are used to develop an isotropic, spatial-temporal log rain rate model assuming that log rain rate is a homogeneous Gaussian random field. This model is developed further to yield closed form expressions for the second order statistics of the associated rain rate, specific attenuation and log specific attenuation random fields. Furthermore, expressions for the temporal covariance of the rain attenuation experienced by pairs of radio links are developed and these expressions are tested against measured rain attenuation data from an experimental link.