Application of M5 Model Tree in Passive Remote Sensing of Thin Ice Cloud Microphysical Properties in Terahertz Region
Application of M5 Model Tree in Passive Remote Sensing of Thin Ice Cloud Microphysical Properties in Terahertz Region
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M5模型树在太赫兹区薄冰云微物理特性被动遥感中的应用
DOI：
10.3390/rs13132569
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发表时间：
2021-07-01
期刊：
影响因子：
5
通讯作者：
Bu, Lingbing
中科院分区：
文献类型：
--
作者：
Dong, Pingyi;Liu, Lei;Bu, Lingbing
本文提出了一种新的太赫兹波段冰云体积等效球径（IWP < 100 g/m2，Dme< 80 μm）的反演方法。利用大气辐射传输模拟器（ARTS）模拟了325.15、448.0、664.0和874.0GHz波段冰云引起的上升流亮温低压。将模拟的前向辐射传输模型作为M5模型树算法的历史数据，构造了一组分段函数来表示模拟的亮温凹陷与IWP之间的关系。在前人研究的基础上，总结了薄冰云IWP和DME的经验关系，并对反演结果进行了优化。利用模拟的亮度温度反演IWP和Dme，并分析了所选通道的反演性能。874.4 ± 6.0 GHz通道的计算结果最准确，这是因为在前向辐射传输模型中，亮温对IWP的变化有很强的响应。为了提高太赫兹波段中高频通道冰云IWP和Dmer反演精度，提出了一种448.0± 3.0 GHz和664.0 ± 4.2 GHz通道联合反演的方法。误差分析表明，874.4 ± 6.0 GHz信道和双信道反演结果是可靠的，IWP反演结果满足前人研究提出的误差要求范围。
This article presents a new method for retrieving the Ice Water Path (IWP), the median volume equivalent sphere diameter (Dme) of thin ice clouds (IWP < 100 g/m2, Dme< 80 μm) in the Terahertz band. The upwelling brightness temperature depressions caused by the ice clouds at 325.15, 448.0, 664.0 and 874.0 GHz channels are simulated by the Atmospheric Radiative Transfer Simulator (ARTS). The simulated forward radiative transfer models are taken as historical data for the M5 model tree algorithm to construct a set of piecewise functions which represent the relation of simulated brightness temperature depressions and IWP. The inversion results are optimized by an empirical relation of the IWP and the Dmefor thin ice clouds which is summarized by previous studies. We inverse IWP and Dmewith the simulated brightness temperature and analyze the inversion performance of selected channels. The 874.4 ± 6.0 GHz channel provides the most accurate results, because of the strong brightness temperature response to the change of IWP in the forward radiative transfer model. In order to improve the thin ice clouds IWP and Dmeretrieval accuracy at the middle-high frequency channels in Terahertz band, a dual-channel inversion method was proposed that combines the 448.0± 3.0 GHz and 664.0 ± 4.2 GHz channel. The error analysis shows that the results of the 874.4 ± 6.0 GHz channel and the dual-channel inversion are reliable, and the IWP inversion results meet the error requirement range proposed by previous studies.