Remote sensing of optical and microphysical properties of cirrus clouds using Moderate-Resolution Imaging Spectroradiometer channels: Methodology and sensitivity to physical assumptions
Remote sensing of optical and microphysical properties of cirrus clouds using Moderate-Resolution Imaging Spectroradiometer channels: Methodology and sensitivity to physical assumptions
复制标题
使用中分辨率成像光谱仪通道遥感卷云的光学和微物理特性：方法论和对物理假设的敏感性
DOI：
--
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
G. McFarquhar
中科院分区：
文献类型：
--
作者：
P. Rolland;K. Liou;M. King;S. Tsay;G. McFarquhar
介绍了一种利用反射太阳光反演卷云微物理和光学特性的方法。该方法基于对地观测系统（EOS）中分辨率成像光谱仪（MODIS）上0.65、1.6和2.2 μm三个通道的双向反射率的相关性。验证研究使用微物理测量和MODIS机载模拟器（MAS）的观测说明了检索的光学深度和平均有效冰晶大小的潜在错误的性质。随后评估了算法中使用的涉及冰晶尺寸分布和形状的物理假设的影响。在用于辐射计算的微物理模型方面，发现冰晶形状假设对反演参数的影响最大。背景表面反射率对检索结果的影响进行了进一步研究，我们表明，为了可靠地推断nonblack卷云参数从太阳反射率测量，它是必要的，以适当地考虑在陆地和海洋表面的背景辐射。最后，我们提出了测量的热带卷云的冰微物理数据作为云的发展和环境温度的函数，以说明验证研究的垂直不均匀性的重要性。
A methodology for the retrieval of cirrus cloud microphysical and optical properties based on observations of reflected sunlight is introduced. The retrieval method is based on correlation of the bidirectional reflectance of three channels, 0.65, 1.6, and 2.2 μm, that are available onboard Earth Observing System (EOS) Moderate-Resolution Imaging Spectroradiometer (MODIS). Validation studies using microphysical measurements and MODIS airborne simulator (MAS) observations illustrate the nature of the potential errors associated with the retrieved optical depth and mean effective ice crystal size. The effects of the physical assumptions involving ice crystal size distribution and shape employed in the algorithm are subsequently assessed. In terms of the microphysical models used for radiation calculations the ice crystal shape assumption is found to have the most significant impact on the retrieved parameters. The effect of the background surface reflectance on the retrieval results is further examined, and we show that in order to reliably infer nonblack cirrus parameters from solar reflectance measurements it is essential to properly account for the background radiation over both land and ocean surfaces. Finally, we present the measured ice microphysical data for tropical cirrus as a function of cloud development and ambient temperature to illustrate the importance of vertical inhomogeneity for validation studies.