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全文摘要次数: 162 全文下载次数: 162
引用本文:

DOI:

10.11834/jrs.20220211

收稿日期:

2020-06-16

修改日期:

2022-02-24

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太赫兹冰云辐射散射特性研究和探测参数设计
陈柯1, 董杉彬1, 李迎雪1, 徐红新2, 谢振超2, 姜丽菲2, 李恩晨2, 吴琼3, 商建3
1.华中科技大学;2.上海航天电子技术研究所;3.国家卫星气象中心
摘要:

星载被动太赫兹遥感是目前最具潜力的冰云探测手段,而理解冰云参数如何影响太赫兹辐射传输过程,掌握太赫兹频段冰云辐射散射特性是实现高精度太赫兹冰云定量探测的前提,对冰云探测仪器的设计和冰云参数反演也非常重要。基于DOTLRT大气辐射传输模式模拟计算太赫兹频段冰云辐射亮温及其雅可比矩阵,以FNL气象再分析资料为初值驱动WRF中尺度模式预报得到冰云参数作为DOTLRT模式的输入。通过与ATMS的183GHz频段观测亮温对比验证了模拟太赫兹冰云亮温具有较好的精度,并且表明太赫兹亮温同时受到冰云中的冰粒子和霰粒子的影响,且具有不同的特性。定量分析了冰云中冰、霰两种粒子的特性参数(等效粒径Dme、路径总量IWP、GWP)和观测几何对冰云太赫兹亮温的影响。在综合了太赫兹亮温的敏感性分析、雅可比矩阵的峰值高度分析和痕量气体吸收的基础上,给出了太赫兹冰云探测器的优化探测频段(183GHz, 243GHz, 325GHz, 448GHz, 664GHz and 874GHz)和观测角度(53±5°)。通过模拟亮温与观测亮温的对比证明了太赫兹冰云探测需要同时考虑冰粒子和霰粒子。提供了冰、霰两种冰云粒子的辐射散射特性,突破现有研究仅仅计算单一冰粒子的局限,可为我国发展冰云太赫兹探测载荷提供技术支撑。

Study on THz radiation and scattering characteristics of ice cloud and sounding parameters design
Abstract:

[Objective]: Spaceborne passive terahertz ice cloud remote sensing technique has been developed over the past decade due to a few potential advantages that complement existing visible and infrared techniques. Since the wavelength of terahertz radiation is comparable to the size of ice particles in cirrus clouds, observed brightness temperature changes from cirrus are well correlated to ice mass. The major objectives of this paper are to provide the terahertz radiation and scattering characteristics of ice particles and graupel particles that make up ice clouds and to understand how ice cloud parameters affect the terahertz radiation transmission, which is important for instrument design and ice cloud parameter retrieval. [Method]: In this study, the terahertz observed brightness temperature and Jacobian matrix are calculated by applying the DOTLRT (Discrete-Ordinate Tangent Linear Radiative Transfer) model to the spatially and microphysically detailed output of ice clouds predicted by the WRF (Weather Research and Forecasting) model and FNL (Final Analysis) reanalysis data. The DOTLRT model use the classical Mie scattering formula to the scattering characteristics of liquid, rain, ice, snow and graupel particles that make up ice clouds. The validity of the simulated terahertz brightness temperature is verified by comparison with the 183GHz brightness temperature observed by ATMS (Advanced Technology Microwave Sounder). The comparison also shows that the terahertz brightness temperature of ice clouds is affected by both ice particles and graupel particles with different properties. Then, the impacts of the observation geometry and parameters of ice particles and graupel particles that make up ice clouds on the terahertz brightness temperature, including Dme (mass equivalent spherical diameter), IWP (Ice Water Path) and GWP (Graupel Water Path), were quantitatively analyzed. [Result]: Finally, the optimized sounding frequency bands (183GHz, 243GHz, 325GHz, 448GHz, 664GHz and 874GHz) and observation angle (53±5°) of the terahertz ice cloud sounding instrument were derived based on the sensitivity analysis of the terahertz brightness temperature, Jacobian matrix and trace gas absorption. [Conclusion]: In this paper, the comparison between the simulated brightness temperature and ATMS observation proves that both ice particles and graupel particles need to be considered in the terahertz ice cloud remote sensing. The terahertz radiation and scattering characteristics of ice particles and graupel particles studied in this paper can provide technical support for the development of the future ice cloud terahertz sounding instrument.

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