Characteristics of the mirror image of precipitation observed by the TRMM precipitation radar
Characteristics of the mirror image of precipitation observed by the TRMM precipitation radar
复制标题
TRMM降水雷达观测降水镜像特征
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
K. Nakamura
中科院分区：
文献类型：
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作者：
Ji Li;K. Nakamura
镜像是当机载或星载雷达用于观测海洋降雨时，来自海洋表面“下方”的降水的虚拟图像。这是由于能量从海面反射到降水，然后通过海面的第二次反射返回雷达。利用TRMM（Tropical Rainfall Measuring Mission使命）降水雷达资料，研究了海洋上空的镜像特征，发现：1）雷达可以清晰地探测到海洋上空的镜像; 2)在最低点和近最低点入射角下，镜像回波与直接雨回波对应良好。3)在弱雨区，镜面回波强度与直达回波功率几乎成正比，但与雷达噪声电平无关。4)在强雨区，雨衰减效应明显。5)镜面回波功率与直射回波功率的比值受雨衰减的影响，雨衰减随明带高度和目标雨距地面距离的变化而变化。此外，为了确认上述特性，进行了简单的模拟。仿真中考虑了信号波动、噪声污染、雨衰减和地表横截面积等因素。模拟结果证实了观测结果。
A mirror image is a virtual image of precipitation from "below" the ocean surface when an airborne or a spaceborne radar is used to view rainfall over the ocean. It is due to a reflection of energy from the sea surface tothe precipitation and back to the radar via a second reflection at the sea surface. The mirror image characteristics were investigated using Tropical Rainfall Measuring Mission (TRMM) precipitation radar data and the following was found. 1) The radar can detect the mirror image clearly over the ocean. 2) The mirror image echo corresponds well to the direct rain echo at nadir and near-nadir incidence angles. 3) In a weak rain region, the mirror echo intensity is nearly proportional to the direct echo power except near the radar noise level. 4) In the strong rain region, rain attenuation effects clearly appear. 5) The ratio of the mirror echo power to the direct echo power is affected by the rain attenuation, which varies with the brightband height and the range of the target rain from surface. Further, a simple simulation was performed in order to confirm the above characteristics. The signal fluctuation, noise contamination, rain attenuation, and surface cross section are taken into account in the simulation. The results of simulation confirmed the observation results.