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Remote sensing of the optical and microphysical properties of cirrus clouds using EOS-MODIS channels.

机译：使用EOS-MODIS通道遥感卷云的光学和微物理特性。

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摘要

Generating global maps that describe the spatial and temporal behavior of the optical and microphysical properties of cirrus clouds can help better characterize the modulation of atmospheric radiation fluxes. In addition, improved knowledge of these properties could provide the basis for the atmospheric correction necessary for the accurate remote sensing of atmospheric and surface constituents.; This dissertation documents the development of a methodology for the remote sensing of cirrus optical depth and mean effective ice crystal size, based on measurements of reflected solar radiation collected by a modern spectroradiometer. The algorithm utilizes lookup tables developed using scattering and radiative transfer methods specifically developed to account for the complex microphysics of cirrus clouds. The retrieved results are validated using concurrent radiometric and microphysical measurements collected during field campaigns targeting cirrus clouds.; The effects of the physical assumptions involving ice crystal microphysics and non-Lambertian surface effects are examined. The microphysical assumptions are found to introduce error bars of approximately 10% and 10–20 μm on the retrieved optical depth and mean effective ice crystal size, respectively. The surface effects are found to have the potential to preclude practical retrievals of thin cirrus properties over complex land surfaces.; Explicit calculations of the emerging cloud base reflectance fields are carried out in order to reduce the uncertainty associated with the variability of the surface reflectance. For ocean surfaces, the anisotropic reflectance is atmospherically corrected using appropriate radiative transfer calculations and the retrieved values of aerosol optical depth based on a simple aerosol microphysical model. For land surfaces, a mosaic of ecosystems is used to compute the anisotropic reflectance associated with the surface terrain variability. We show that using these explicit computations of the emerging cloud base reflectance, thin cirrus optical depth and ice crystal size over ocean surfaces can be retrieved accurately. Moreover, uncertainties in the retrieved optical depth and ice crystal size over complex land surfaces are reduced by 20% and 45%, respectively.
机译：生成描述卷云光学和微观物理特性的时空行为的全局图可以帮助更好地表征大气辐射通量的调制。另外，对这些性质的了解增加可以为对大气和地面成分进行精确遥感所必需的大气校正提供基础。本文基于对现代分光辐射仪收集的反射太阳辐射的测量结果，开发了一种用于卷云光学深度和平均有效冰晶尺寸遥感方法的开发。该算法利用了查找表，该查找表是使用散射和辐射转移方法开发的，这些方法是专门为解决卷云的复杂微观物理问题而开发的。使用针对卷云的野外活动期间收集的同时进行的辐射测量和微物理测量，对检索到的结果进行验证。检验了涉及冰晶微观物理学和非朗伯表面效应的物理假设的影响。微观物理假设被发现在所获取的光学深度和平均有效冰晶尺寸上分别引入了大约10％和10–20μm的误差线。发现表面效应有可能阻止在复杂的陆地表面上对薄卷云特性进行实际恢复。为了减少与表面反射率变化相关的不确定性，对新兴的云层反射率场进行了显式计算。对于海洋表面，可使用适当的辐射转移计算和基于简单的气溶胶微物理模型的气溶胶光学深度的取回值对大气的各向异性反射率进行校正。对于陆地表面，使用生态系统的镶嵌来计算与表面地形变化相关的各向异性反射率。我们表明，使用这些新兴的云层反射率的显式计算，可以准确地检索海洋表面的薄卷云光学深度和冰晶尺寸。此外，在复杂陆地表面上获取的光学深度和冰晶尺寸的不确定性分别降低了20％和45％。

著录项

  • 作者

    Rolland, Philippe.;

  • 作者单位

    University of California, Los Angeles.;

  • 授予单位 University of California, Los Angeles.;
  • 学科 Physics Atmospheric Science.; Remote Sensing.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 145 p.
  • 总页数 145
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 大气科学（气象学）;遥感技术;
  • 关键词

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