The impact of explicit cloud boundary information on ice cloud microphysical property retrievals from infrared radiances
The impact of explicit cloud boundary information on ice cloud microphysical property retrievals from infrared radiances
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明确的云边界信息对红外辐射冰云微物理性质反演的影响
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
G. Stephens
中科院分区：
文献类型：
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作者：
S. Cooper;T. L’Ecuyer;G. Stephens
[1]卷云对地-气系统的辐射平衡有着深远的影响。准确表示它们的辐射特性对于了解气候和预测气候变化至关重要。本文将分裂窗卷云反演技术应用于最优估计框架中，便于直接包含来自互补传感器的显式云边界信息，并提供一套诊断工具来评估所有反演量中的主要不确定性源。利用所提取的微物理性质中的误差来确定在计算全球尺度辐射预算时产生的误差。在没有明确云边界信息的情况下，光学深度和有效半径的不确定度分别从�45%和�80%减小到�15%和�60%，当包括基于雷达或基于激光雷达的准确估计时。结果表明，准确的云边界信息对卷云光学性质的改善可以使它们对地球辐射平衡的影响的模拟精度提高3倍之多。地球观测系统(EOS)Aqua卫星上的中分辨率成像光谱仪(MODIS)仪器的共址红外辐射和CloudSat卫星的云雷达观测不久将使本文所述的反演工作能够融入对全球范围云特性垂直分布的业务反演。指标术语：0320大气组成和结构：云物理和化学；3359气象和大气动力学：辐射过程；3360气象和大气动力学：遥感；3374气象和大气动力学：热带气象学；3394气象和大气动力学：仪器和技术；关键词：卷云，分裂窗，云卫星，辐射通量
[1] Cirrus clouds have a profound impact on the radiation balance of the Earth–atmosphere system. Accurate representation of their radiative properties is critical to understanding climate and predicting climate change. This paper casts the split-window cirrus cloud retrieval technique in an optimal estimation framework facilitating direct inclusion of explicit cloud boundary information from complementary sensors as well as providing a suite of diagnostic tools for evaluating the dominant sources of uncertainty in all retrieved quantities. Errors in retrieved microphysical properties are used to determine the resulting errors in the calculation of global-scale radiative budgets. Uncertainties in optical depth and effective radius are found to diminish from � 45% and � 80%, respectively, in the absence of explicit cloud boundary information to � 15% and � 60% when accurate radarbased or lidar-based estimates are included. It is demonstrated that the improvements to cirrus cloud optical properties afforded by accurate cloud boundary information may lead to as much as a factor of 3 increase in the accuracy to which their impact on the Earth’s radiative balance can be modeled. Colocated infrared radiances from the ModerateResolution Imaging Spectroradiometer (MODIS) instrument aboard the Earth Observing System (EOS) Aqua satellite and cloud radar observations from the CloudSat satellite will soon allow the retrieval presented here to be integrated into an operational retrieval of the vertical distribution of cloud properties on a global scale. INDEX TERMS: 0320 Atmospheric Composition and Structure: Cloud physics and chemistry; 3359 Meteorology and Atmospheric Dynamics: Radiative processes; 3360 Meteorology and Atmospheric Dynamics: Remote sensing; 3374 Meteorology and Atmospheric Dynamics: Tropical meteorology; 3394 Meteorology and Atmospheric Dynamics: Instruments and techniques; KEYWORDS: cirrus clouds, split-window, CloudSat, radiative fluxes