Reconstruction of cloud geometry using a scanning cloud radar
Reconstruction of cloud geometry using a scanning cloud radar
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DOI：
10.5194/amt-8-2491-2015
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发表时间：
2014-11
影响因子：
3.8
通讯作者：
Florian Ewald;C. Winkler;T. Zinner
中科院分区：
文献类型：
--
作者：
Florian Ewald;C. Winkler;T. Zinner
抽象的。云是天气气候预报不确定性的主要原因之一。部分原因是云微物理学遥感的局限性。目前的方法往往使用被动光谱测量的云微物理参数的遥感。三维（3-D）辐射传输效应和云的不均匀性引入了很大的不确定性。这种效应主要是由云面的未知方向或云上的阴影区域引起的。有了这类关于云的几何形状的额外知识，以高空间分辨率对云的特性进行被动地面遥感将得到极大的改进。为此，在这项工作中开发了一种从云雷达测量数据精确重建3-D云几何形状的方法。使用雷达模拟器和模拟被动测量的模型云的基础上的大涡模拟（LES），不同的雷达扫描分辨率和不同的插值方法的影响进行了评估。实际上，由于云层变化很快，必须在扫描分辨率和扫描持续时间之间找到一个折衷。合理的选择是1到2度的扫描分辨率。确定的最合适的插值程序是重心插值法。三维重建方法演示使用雷达扫描对流云的情况下，与慕尼黑miraMACS，35 GHz的扫描云雷达。作为一个成功的概念证明，在雷达位置收集的摄像机图像再现所观察到的云的情况下，通过3-D体积重建和3-D辐射传输模拟。所提出的重建方法提供的数据集将有助于被动光谱地面云侧的测量，以检索微物理参数。
Abstract. Clouds are one of the main reasons of uncertainties in the forecasts of weather and climate. In part, this is due to limitations of remote sensing of cloud microphysics. Present approaches often use passive spectral measurements for the remote sensing of cloud microphysical parameters. Large uncertainties are introduced by three-dimensional (3-D) radiative transfer effects and cloud inhomogeneities. Such effects are largely caused by unknown orientation of cloud sides or by shadowed areas on the cloud. Passive ground-based remote sensing of cloud properties at high spatial resolution could be crucially improved with this kind of additional knowledge of cloud geometry. To this end, a method for the accurate reconstruction of 3-D cloud geometry from cloud radar measurements is developed in this work. Using a radar simulator and simulated passive measurements of model clouds based on a large eddy simulation (LES), the effects of different radar scan resolutions and varying interpolation methods are evaluated. In reality, a trade-off between scan resolution and scan duration has to be found as clouds change quickly. A reasonable choice is a scan resolution of 1 to 2\degree. The most suitable interpolation procedure identified is the barycentric interpolation method. The 3-D reconstruction method is demonstrated using radar scans of convective cloud cases with the Munich miraMACS, a 35 GHz scanning cloud radar. As a successful proof of concept, camera imagery collected at the radar location is reproduced for the observed cloud cases via 3-D volume reconstruction and 3-D radiative transfer simulation. Data sets provided by the presented reconstruction method will aid passive spectral ground-based measurements of cloud sides to retrieve microphysical parameters.