利用辐射数据构建云物理结构

霍娟

doi:10.3878/j.issn.1006-9895.1801.17156

利用辐射数据构建云物理结构

doi: 10.3878/j.issn.1006-9895.1801.17156

霍娟

中国科学院大气物理研究所中层大气和全球环境探测开发重点实验室, 北京 100029

基金项目:

国家自然科学基金项目 41275040

国家自然科学基金项目 41775032

详细信息

作者简介:
霍娟, 女, 1977年出生, 博士、副研究员, 主要从事云相关遥感与辐射研究。E-mail:huojuan@mail.iap.ac.cn

中图分类号: P401
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出版历程
- 收稿日期: 2017-04-21
- 网络出版日期: 2018-01-16
- 刊出日期: 2018-09-15

Constructing Cloud Physical Structure Based on Radiation Data

Juan HUO

Key Laboratory for Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029

Funds:

National Natural Science Foundation of China 41275040

National Natural Science Foundation of China 41775032

摘要

摘要: 本文运用CloudSat卫星上搭载的雷达探测数据和AQUA卫星搭载的辐射光谱仪探测数据，选择2007年1月至2010年12月期间，地理位置位于（15°~45°N，145°~165°E）区域内（远海）发生的云场数据开展分析，研究云的物理结构特征与其光谱辐射特性的相互关系。不同光谱波段对云物理结构变化的响应情况各有不同，首先从MODIS光谱仪22个云相关光谱波段中分析并选择出与云物理结构特征密切相关的光谱组合（包含13个波段），而后开展了这些光谱波段的云辐射特性与云物理结构特征的相互变化关系研究。统计分析表明，在外部大气、地表条件以及太阳入射辐射变化不大情况下，云的结构变化与其光谱辐射变化之间总体存在单调相关关系，物理结构变化不大的云廓线之间其光谱辐射的变化也小，反之也成立，即光谱辐射变化小的云廓线之间物理结构变化也小。从而，对于某些内部物理结构特征未知的云，利用与其光谱辐射特性相近的云结构数据可实现自身垂直结构信息的重建。基于光谱辐射相近则云物理结构很可能相近的特点，本文对未知云场的物理结构重建开展了模拟试验，试验结果表明光谱相近原则匹配物理结构的方法一定程度上能够实现云物理结构的构建，为利用被动遥感数据推测云物理结构特征研究提供参考。
- MODIS光谱仪 /
- CloudSat卫星 /
- 垂直结构 /
- 三维云 /
- 辐射
Abstract: Radars can actively detect cloud internal physical structure while radiometers can passively measure the integral radiation characteristics of clouds. This study uses cloud products from CloudSat (active detection) and AQUA (passive detection) during the period from 1 January 2007 to 31 December 2010 over the area (15°-45°N, 145°-165°E) to study the relationships between the variations of radiation characteristics and the physical structure characteristics of clouds. MODIS (MODerate-resolution Imaging Spectroradiometer) uses 22 wavebands that have various sensitivities to cloud physical properties to measure radiation from cloud. Firstly, 13 wavebands demonstrating high correlation with the cloud physical structures are screened out based on correlation analysis. Then, the relationship between the radiation variations of these 13 wavebands and changes in the cloud physical structures are studied. Statistical analysis shows that the variation in cloud radiation illustrates a monotonic change with the variation in cloud physical structures when conditions (e.g., atmospheric environment, surface characteristics) change little. This means two cloud profiles with close radiative properties may also have similar physical structures. For some cloud profiles with unknown internal structures, their vertical structures can be inferred from other cloud profiles with similar spectral radiative properties. Preliminary tests for reconstructing the cloud vertical structure are performed and it is found that cloud physical structures constructed based on the nearest radiative characteristics principle are close to the structures measured by radars.
- MODIS (MODerate-resolution Imaging Spectroradiometer) /
- CloudSat satellite /
- Cloud structure /
- 3D cloud /
- Radiation

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图 1 MODIS与CPR观测视场范围示例。方形格点代表MODIS的数据像元，灰色椭圆代表CPR的单廓线扫描范围

Figure 1. Footprints of MODIS and CPR (Cloud Profiling Radar, gray ellipse)

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图 2 发生于2007年8月14日位于（15°~45°N，145°~165°E）区域内的云例：（a）MODIS所测辐射值（单位：W m⁻² μm ⁻¹ sr⁻¹）；（b）CPR观测雷达反射率值Z_e（单位：dBZ）

Figure 2. Clouds occurring on 14 August 2007 over region (15°–45°N, 145°–165°E): (a) The radiance (units: W m⁻² μm ⁻¹ sr⁻¹) measured by MODIS; (b) the radar reflectivity factor Z_e (units: dBZ) measured by CPR

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图 3 根据图 2云场MODIS的22个波段辐射值计算彼此之间的辐射相关系数。图中横坐标和纵坐标都是波段号，“B”代表波段

Figure 3. Correlation coefficients of radiation between 22 MODIS wavebands for cloud case in Fig. 2. The x-axis and y-axis show the numbers of wavebands, letter "B" means waveband

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图 4 根据2007~2010年区域（15°~45°N，145°~165°E）内MODIS的22个光谱通道探测的所有云廓线辐射数据，计算各通道之间的辐射相关系数：（a）将所有云廓线集中一起计算辐射相关系数；（b）针对各天云廓线数据分别计算通道辐射相关系数，然后求平均

Figure 4. Correlation coefficients of radiation between 22 MODIS wavebands for all cloudy profiles occurred over the area (15°–45°N, 145°–165°E) during 2007–2010: (a) Correlation coefficients of radiation calculated from all cloudy profiles; (b) the mean value of those radiation correlation coefficients which are calculated individually from cloudy profiles occurred in the same day.

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图 5 一个结构距离和辐射距离分析示例：（a）2008年12月15日所选区域内CPR观测雷达反射率因子Z_e；（b）以图a中红色线所在云廓线为参照计算的各廓线与其之间的辐射距离和结构距离；（c）辐射距离随结构距离单调变化

Figure 5. A cloud case showing the distribution of Dst (Standardized Euclidean distance of structure) and Drd (Standardized Euclidean distance of radiation): (a) Z_e measured by CPR on 15 December 2008 in the selected area; (b) Dst and Drd between the red profile in Fig. a and other profiles; (c) the monotonic relation between Dst and Drd

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图 6 （a）8条云廓线的Z_e垂直结构；（b）黑色方点廓线与其他廓线的辐射距离以及结构距离

Figure 6. Contrast of the Drds and Dsts between cloud profiles with different vertical structures: (a) Vertical structures of eight cloud pofiles; (b) Drds and Dsts of the black square profile with other profiles

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图 7 （a）MODIS通道一的辐亮度（单位：W m^-2 μm^-1 sr^-1）分布，图上白色实线A为CPR扫描路径，白色虚线B距离白色实线A大约10 km。（b）从上到下分别对应图a中线段B、线段A和线段C的垂直结构分布。线段B和C的云结构构建是基于最近辐射特征原则匹配而成

Figure 7. (a) Radiance (units: W m^-2 μm^-1 sr^-1) of waveband 1 from MODIS, line A (white solid line) is the scan path of CPR, line B (white dashed line) is about 10 km from line A. (b) The panel from top to bottom shows the cloud vertical structures of line B, Line A, and Line C. Vertical structures of line B and line C are constructed based on the nearest radiative characteristics principle

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表 1 MODIS光谱仪的22个云相关光谱波段宽度、分辨率以及主要用途

Table 1. The bandwidth, data resolution, and primary use of 22 MODIS (MODerate-resolution Imaging Spectroradiometer) wavebands which are related to cloud

波段	波段宽度	数据分辨率/m	主要用途
1	620~670 nm	250	地表/云/气溶胶边界层
2	841~867 nm	250
3	459~479 nm	500	地表/云/气溶胶特征
4	545~565 nm	500
5	1230~1250 nm	500
6	1628~1652 nm	500
7	2105~2155 nm	500
17	890~920 nm	1000	云/大气水汽特征
18	931~941 nm	1000
19	915~965 nm	1000
20	3.66~3.84 μm	1000	地表/云温度
26	1.36~1.39 μm	1000	卷云/水汽/湿度
27	6.535~6.895 μm	1000
28	7.175~7.475 μm	1000
29	8.4~8.7 μm	1000	云属性
30	9.58~9.88 μm	1000	臭氧
31	10.78~11.28 μm	1000	地表/云温度
32	11.77~12.27 μm	1000
33	13.185~13.485 μm	1000	云高/云量
34	13.485~13.785 μm	1000
35	13.785~14.085 μm	1000
36	14.085~14.385 μm	1000

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