| 利用MODIS数据反演多层云光学厚度和有效粒子半径 |
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| 引用本文： | 叶晶,李万彪,严卫.利用MODIS数据反演多层云光学厚度和有效粒子半径[J].气象学报,2009,67(4):613-622. |
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| 作者姓名： | 叶晶 李万彪 严卫 |
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| 作者单位： | 叶晶(北京大学物理学院大气科学系,北京,100871;解放军95871部队,衡阳,421002);李万彪(北京大学物理学院大气科学系,北京,100871);严卫(解放军理工大学气象学院,南京,211101) |
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| 基金项目： | 国家科技支撑计划课题 |
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| 摘 要： | 利用卫星资料反演云微物理参数不仅有助于对天气变化的监测和预报,而且对人工影响天气的研究十分有益.目前卫星反演云微物理参数的算法一般是假设视场中只有一层云,但是实际环境中多层云出现很频繁.文中研究了多层云的光学厚度和有效粒子半径微物理参数的反演算法,主要针对薄的冰云覆盖在低层水云的多层云情形.算法利用中分辨率成像光谱仪(MODIS)吸收通道和非吸收通道同时进行反演,在此基础上利用SBDART辐射传输模式模拟冰云覆盖在低层水云上的多层云对云微物理参数反演的影响,模拟表明反演时将多层云作为单层云处理会使反演结果产生较大误差.为此,文中提出了云光学厚度和有效粒子半径反演算法中要考虑多层云的因素,并设计了一套云光学厚度和有效粒子半径反演方案.该方案使用SBDART辐射传输模式建立不同观测几何条件、下垫面类型、大气环境等条件下以光学厚度和有效粒子半径为函数变量的多层云、水云和冰云辐射查找表.经过云检测、云相态识别和多层云检测后,在该查找表的基础上,对MODIS通道1和通道7的数据采用最小方差拟合法反演光学厚度、有效粒子半径.利用该方案对2006年7月12日TERRA卫星MODIS数据进行反演试验,反演结果与NASA发布的MOD06产品中云的光学厚度和有效粒子半径的结果较一致,表明方案具有合理性.
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| 关 键 词： | 多层云 光学厚度 有效粒子半径 |
| 收稿时间： | 2008/1/21 0:00:00 |
| 修稿时间： | 2009/4/17 0:00:00 |
Retrieval of the optical thickness and effective radius of multilayered
cloud using MODIS data |
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| YE Jing,LI Wanbiao and YAN Wei.Retrieval of the optical thickness and effective radius of multilayered
cloud using MODIS data[J].Acta Meteorologica Sinica,2009,67(4):613-622. |
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| Authors: | YE Jing LI Wanbiao and YAN Wei |
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| Institution: | Department of Atmospheric Sciences, Peking University, Beijing 100871, China; No.95871 Navy of PLA, Hengyang 421002, China,Department of Atmospheric Sciences, Peking University, Beijing 100871, China and Institute of Meteorology. PLA University of Science & Technolgy, Nanjing 211101, China |
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| Abstract: | The retrieval of cloud microphysical properties using satellite data is crucial to not only weather monitoring and forecast but also the weather modification research. At present the main assumption for the operational retrieval of cloud microphysical properties is that only single layered clouds exist in the view field of the satellite. However, multilayer clouds appear very frequently. An algorithm using a combination of MODIS absorbing and nonabsorbing channels is presented for the retrieval of the optical thickness and effective particle radius of multilayer cloud, specially for cases with optically thin ice clouds overlying lower-level water clouds. Base on this algorithm the impact of the multilayer cloud that ice cloud lies over water cloud on the retrieval of cloud microphysical properties is simulated with SBDART radiative transfer model. The stimulated result shows that the error caused by considering a multilayer cloud as a single layer cloud is evident. In terms of the stimulation, an algorithm for the retrieval of the optical thickness and effective particle radius considering the effect of the multilayer cloud is presented in this paper, and a scheme is designed for the retrieval of the optical thickness and effective particle radius. In this scheme, the radiative databases of the optical thickness and effective particle radius of water cloud, ice cloud and multilayered cloud are established with SBDART radiative transfer model, considering various geometrical conditions, surface types, and atmospheric environment. After the detection of cloud mask, cloud phase and multilayer cloud, the optical thickness and effective particle radius are retrieved based on those databases, processing the channel 1 data and channel 7 data of MODIS with the method of least-squares fit. The scheme is applied to the MODIS data of TERRA on 12 July 2007, and the case study shows that our retrieval results are in good agreement with those of the MOD06 released by NASA, which indicates that the scheme is reasonable. |
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| Keywords: | SBDART |
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