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首页> 外文学位 >A study of tropical cirrus: Multisensor algorithm development for space-based observation and the role of cirrus in regulating the humidity of the tropical upper troposphere.
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A study of tropical cirrus: Multisensor algorithm development for space-based observation and the role of cirrus in regulating the humidity of the tropical upper troposphere.

机译：热带卷云的研究：用于天基观测的多传感器算法开发以及卷云在调节热带对流层上部湿度中的作用。

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摘要

Cirrus clouds, through their radiative properties which are determined by their microphysical properties and macroscopic structure, have a strong radiative effect in the climate system. A suite of algorithms prepared for the A-Train are developed to derive cirrus cloud properties from observational data. Algorithms convert the data streams from the individual multiple remote sensors into layer-averaged cirrus bulk microphysical properties. Due to the wide range of cirrus properties that can be expected in the global upper troposphere, the algorithms are capable of treating cirrus layers that range from very tenuous and below the detection threshold of cloud radars, to layers that can cause significant lidar attenuation. Two field cases from the CRYSTAL-FACE campaign are used to illustrate the requirements for an algorithm suite and multiple remote sensors and to demonstrate the implementation of the algorithms. The algorithms are also compared to validated ground-based retrievals.; Water vapor is the principal contributor to the earth's greenhouse effect due to the dominance of infrared absorption. Motivated by the coverage difference between cirrus clouds and convection systems, the relationship between upper-tropospheric humidity (UTH) and cirrus is explored to explain the role of cirrus to moisten the upper troposphere in the tropical region. Using satellite observations, we show that UTH is highly correlated with cirrus-cloud coverage, especially in the regions without frequent and widespread active convection. The intra annual variations of the high cloud coverage and the UTH averaged between 5°S and 5°N agree well with the MJO structure, which indicates that the UTH must be primarily controlled by the large-scale dynamics. The UTH tendency change with the presence of cirrus is explored from a Lagrangian perspective. The results show that thicker cirrus is associated with higher moistening rates than thin cirrus and clear-sky conditions, and the periods of cirrus decay are related to enhanced moistening of the upper troposphere compared with clear-sky conditions. However, the large scatter and the large range of humidities indicate that cirrus ice water content (IWC) alone can not explain the variability of tropical moisture. So, the presence of cirrus clouds perturbs the UTH in relatively small scale. It is also shown by a model simulation that cirrus clouds, through their radiative effects, cause redistribution of the upper-tropospheric water vapor resulting in a moistening of the cloudy columns.
机译：卷云通过其辐射特性（由其微观物理特性和宏观结构决定）在气候系统中具有很强的辐射作用。开发了一套为A-Train准备的算法，以从观测数据中导出卷云特性。算法将来自单个多个远程传感器的数据流转换为平均层数的卷云体微物理特性。由于在全球对流层中可以预期到大范围的卷云特性，因此该算法能够处理从非常微弱且低于云雷达的检测阈值的卷云层，到可以引起显着激光雷达衰减的层。 CRYSTAL-FACE活动的两个现场案例用于说明算法套件和多个远程传感器的要求，并演示算法的实现。还将算法与经过验证的地面检索进行比较。由于红外吸收的优势，水蒸气是导致地球温室效应的主要因素。由卷云和对流系统之间的覆盖差异引起，探讨了对流层上湿度（UTH）与卷云之间的关系，以解释卷云在热带地区增湿对流层中的作用。利用卫星观测，我们发现UTH与卷云的覆盖高度相关，尤其是在没有频繁和广泛的主动对流的地区。高云层的年内变化和平均UTH在5°S和5°N之间的平均变化与MJO结构非常吻合，这表明UTH必须主要由大规模动力学控制。从拉格朗日的角度探讨了存在卷云时UTH趋势的变化。结果表明，与薄卷云和晴空条件相比，较厚的卷云与较高的增湿速率有关，与晴空条件相比，卷云的衰变时期与对流层上层增湿程度有关。但是，大范围的散布和大范围的湿度表明仅卷云冰水含量（IWC）不能解释热带水分的变化。因此，卷云的存在以较小的规模干扰了UTH。模型仿真还表明，卷云通过其辐射效应引起对流层上层水蒸气的重新分布，从而导致阴天柱变湿。

著录项

  • 作者

    Zhang, Yuying.;

  • 作者单位

    The University of Utah.;

  • 授予单位 The University of Utah.;
  • 学科 Physics Atmospheric Science.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 184 p.
  • 总页数 184
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 大气科学（气象学）;
  • 关键词

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