An algorithm for retrieval of cloud microphysics using 95-GHz cloud radar and lidar
An algorithm for retrieval of cloud microphysics using 95-GHz cloud radar and lidar
复制标题
使用 95 GHz 云雷达和激光雷达检索云微物理的算法
DOI：
10.1029/2001jd001225
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发表时间：
2003
影响因子：
--
通讯作者：
H. Kumagai
中科院分区：
文献类型：
--
作者：
H. Okamoto;S. Iwasaki;M. Yasui;H. Horie;H. Kuroiwa;H. Kumagai
[1]利用95GHz（3.16mm）测云雷达和波长为0.532 μm的激光雷达，提出了一种新的反演云中冰晶有效尺寸和冰水含量的正演算法。单独使用雷达或激光雷达有一个基本的困难，以获得云的微观物理，因为云粒子的大小分布的各种各样的，虽然它是有效的，以获得云的宏观物理信息，如云的边界。雷达和激光雷达的结合使用可以克服这个问题。该算法的一个独特之处是衰减校正的激光雷达信号根据云微物理确定的雷达和激光雷达信号的后向散射和消光查找表。因此，组合系统能够检索有效半径（reff）和冰水含量（IWC）的垂直剖面。我们进行了几个数值分析的检索值的潜在来源的错误，即，尺寸分布的形状，在雷达和激光雷达信号的偏差，以及多重散射的影响。然后，我们提供的配方，描述作为给定的偏差和光学厚度的函数的检索错误。最后，我们演示了2000年2月在日本鹿岛进行的卷云地面观测的微物理反演。我们研究了reff，IWC，下降速度，和去极化率的垂直分布以及它们之间的相互关系。粒子的半径在云底附近最大，粒子的下落速度也呈现出与reff趋势一致的趋势。没有现场测量来验证观测所检索的参数。相反，支持参数的基础上，从文献中的云微物理参数之间的关系的预期行为的信息。
[1] We develop a new forward algorithm for the retrieval of effective size and ice water content (IWC) of ice crystals in clouds by using collocated 95-GHz (3.16 mm) cloud radar and lidar with the wavelength of 0.532 μm. Use of radar or lidar alone has a fundamental difficulty to obtain cloud microphysics because of the wide variety of size distributions of cloud particles, though it is effective to obtain cloud macrophysical information such as cloud boundaries. The combined use of radar and lidar can overcome this problem. One unique feature of the algorithm is the attenuation-correction to the lidar signals according to the cloud microphysics determined by look-up tables of backscattering and extinction for the radar and lidar signals. Consequently, the combined system enables the retrieval of vertical profiles of the effective radius (reff) and ice water content (IWC). We perform several numerical analyses of the retrieved values for potential sources of errors, that is, the shape of the size distribution, biases in the radar and lidar signals, and the effect of multiple scattering. Then we provide the formulations that describe the retrieval errors as a function of the given bias and optical thickness. Finally, we demonstrate retrieval of microphysics for ground-based observation of cirrus clouds in February 2000 in Kashima, Japan. We examine the vertical distributions of reff, IWC, fall velocity, and depolarization ratio as well as the interrelationships between them. The radius of the particles turns out to be the largest near the cloud bottom, and the fall velocity also shows a trend consistent with the reff tendency. There are no in situ measurements to validate the retrieved parameters for the observations. Instead, supporting arguments are given on the basis of information about the expected behavior of the relationships between the cloud microphysical parameters from the literature.