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Author: Yong-Keun Lee Publisher: ISBN: Category : Languages : en Pages :
Book Description
This dissertation reports on three different yet related topics in light scattering computation, radiative transfer simulation, and remote sensing implementation, regarding the cloud properties and the retrieval of cloud properties from satellite-based infrared radiometric measurements. First, the errors associated with the use of circular cylinders as surrogates for hexagonal columns in computing the optical properties of pristine ice crystals at infrared (8-12 [micron]) wavelengths are investigated. It is found that the differences between the results for circular cylinders and hexagonal columns are on the order of a few percent at infrared wavelengths. Second, investigated in this dissertation are the outgoing broadband longwave and window channel radiances at the top-of-atmosphere under clear-sky conditions on the basis of the data acquired by the Cloud and the Earth's Radiant Energy System (CERES) instrument onboard the NASA Terra satellite platform. Based on the comparison of the observed broadband radiances with those obtained from rigorous radiative transfer simulations, it is found that the theoretical results tend to be larger than their measured counterparts. Extensive sensitivity studies regarding the uncertainties of various parameters were carried out. Within the considered uncertainties of various factors, the computed radiances are still larger than the observed radiances if thin cirrus clouds are excluded. Thus, a potential cause for the differences could be associated with the presence of thin cirrus clouds whose visible optical thickness is smaller than approximately 0.3. Third, presented in this dissertation is an illustration of the application of hyperspectral infrared channel observations to the retrieval of the cloud properties. Specifically, the hyperspectral measurements acquired from the Atmospheric Infrared Sounder (AIRS) aboard the NASA Aqua platform are used to infer cloud top pressure, effective cloud amount, cloud thermodynamic phase, cloud optical thickness, and the effective size of cloud particles. The AIRS-based retrievals are compared with the counterparts of the operational cloud products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). The two retrievals agree reasonably well except for the retrieved cloud effective particle size. Furthermore, the diurnal and seasonal contrasts of cloud properties are also investigated on the basis of the cloud properties retrieved from the AIRS data.
Author: Yong-Keun Lee Publisher: ISBN: Category : Languages : en Pages :
Book Description
This dissertation reports on three different yet related topics in light scattering computation, radiative transfer simulation, and remote sensing implementation, regarding the cloud properties and the retrieval of cloud properties from satellite-based infrared radiometric measurements. First, the errors associated with the use of circular cylinders as surrogates for hexagonal columns in computing the optical properties of pristine ice crystals at infrared (8-12 [micron]) wavelengths are investigated. It is found that the differences between the results for circular cylinders and hexagonal columns are on the order of a few percent at infrared wavelengths. Second, investigated in this dissertation are the outgoing broadband longwave and window channel radiances at the top-of-atmosphere under clear-sky conditions on the basis of the data acquired by the Cloud and the Earth's Radiant Energy System (CERES) instrument onboard the NASA Terra satellite platform. Based on the comparison of the observed broadband radiances with those obtained from rigorous radiative transfer simulations, it is found that the theoretical results tend to be larger than their measured counterparts. Extensive sensitivity studies regarding the uncertainties of various parameters were carried out. Within the considered uncertainties of various factors, the computed radiances are still larger than the observed radiances if thin cirrus clouds are excluded. Thus, a potential cause for the differences could be associated with the presence of thin cirrus clouds whose visible optical thickness is smaller than approximately 0.3. Third, presented in this dissertation is an illustration of the application of hyperspectral infrared channel observations to the retrieval of the cloud properties. Specifically, the hyperspectral measurements acquired from the Atmospheric Infrared Sounder (AIRS) aboard the NASA Aqua platform are used to infer cloud top pressure, effective cloud amount, cloud thermodynamic phase, cloud optical thickness, and the effective size of cloud particles. The AIRS-based retrievals are compared with the counterparts of the operational cloud products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). The two retrievals agree reasonably well except for the retrieved cloud effective particle size. Furthermore, the diurnal and seasonal contrasts of cloud properties are also investigated on the basis of the cloud properties retrieved from the AIRS data.
Author: Gary E. Thomas Publisher: Cambridge University Press ISBN: 9780521890618 Category : Nature Languages : en Pages : 554
Book Description
Provides a foundation of the theoretical and practical aspects of radiative transfer, for the atmospheric, oceanic and environmental sciences.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The optical properties of aerosol particles are the controlling factors in determining direct aerosol radiative forcing. These optical properties depend on the chemical composition and size distribution of the aerosol particles, which can change due to various processes during the particles' lifetime in the atmosphere. Over the course of this project we have studied how cloud processing of atmospheric aerosol changes the aerosol optical properties. A counterflow virtual impactor was used to separate cloud drops from interstitial aerosol and parallel aerosol systems were used to measure the optical properties of the interstitial and cloud-scavenged aerosol. Specifically, aerosol light scattering, back-scattering and absorption were measured and used to derive radiatively significant parameters such as aerosol single scattering albedo and backscatter fraction for cloud-scavenged and interstitial aerosol. This data allows us to demonstrate that the radiative properties of cloud-processed aerosol can be quite different than pre-cloud aerosol. These differences can be used to improve the parameterization of aerosol forcing in climate models.
Author: Kuo-Nan Liou Publisher: Cambridge University Press ISBN: 0521889162 Category : Science Languages : en Pages : 461
Book Description
This volume outlines the fundamentals and applications of light scattering, absorption and polarization processes involving ice crystals.
Author: Peter Hobbs Publisher: Elsevier ISBN: 0323140971 Category : Science Languages : en Pages : 512
Book Description
Clouds: Their Formation, Optical Properties, and Effects deals with the formation of clouds as well as the theoretical and experimental aspects of their microphysical and optical properties. Discussions are grouped under the headings of structure of clouds, interaction of passive radiation with clouds, and interaction of active radiation with clouds. This book is organized into three sections and has 11 chapters. After analyzing the spatial and temporal scales involved in the formation and organization of clouds and precipitation, this text examines the microphysical measurement techniques used in probing the microstructure of clouds. The reader is then methodically introduced to the microstructure of atmospheric clouds and precipitation; the formation and structure of fog; and basic shortwave characteristics of “ideal clouds. The temporal behavior of clouds and their interaction with the radiation field are considered, along with the possible effects of cloud models in general circulation studies. The remaining chapters explore the light scattering properties of ice crystals and the radiative characteristics of ice clouds; the laser measurements in clouds; the transmission and reflectivity of ice clouds by active probing; and the theory of multiple scattering of laser beams in clouds. The book concludes by presenting the measurements of the temporal and spatial spreading of a blue-green pulse through clouds and fogs as a function of optical thickness and receiver field-of-view. This text will be helpful to advanced researchers and program managers in terms of reviewing the state of the art and identifying those areas requiring further research efforts.
Author: Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The specific objective of this research has been the development and improvement of theoretical models to simulate the effect of nonsphericity on single scattering properties of cirrus cloud particles in the visible and infrared spectral regions. First, we have shown that using a matrix inversion scheme based on a special LU factorization rather than on the standard Gaussian elimination significantly improves the numerical stability of T-matrix computations for nonabsorbing and weakly absorbing nonspherical particles. Second, we use exact T-matrix computations and the Kirchhoff approximation to show that the delta function transmission peak predicted by the GO approximation for hexagonal ice crystals is an artifact of GO completely ignoring physical optics effects and must be convolved with the Fraunhofer pattern, thereby producing a phase function component with an angular profile similar to the standard diffraction component. Third, we have used the improved T-matrix method to compute the linear depolarization ration for polydispersions of randomly oriented ice spheroids, circular cylinders, and Chebyshev particles with sizes typical of young contrails. We have shown that ice crystals with effective radii as small as several tenths of a micron can already produce 3 exceeding 0.5 at visible wavelengths.
Author: Constantin Andronache Publisher: Elsevier ISBN: 012810550X Category : Science Languages : en Pages : 302
Book Description
Mixed-Phase Clouds: Observations and Modeling presents advanced research topics on mixed-phase clouds. As the societal impacts of extreme weather and its forecasting grow, there is a continuous need to refine atmospheric observations, techniques and numerical models. Understanding the role of clouds in the atmosphere is increasingly vital for current applications, such as prediction and prevention of aircraft icing, weather modification, and the assessment of the effects of cloud phase partition in climate models. This book provides the essential information needed to address these problems with a focus on current observations, simulations and applications. Provides in-depth knowledge and simulation of mixed-phase clouds over many regions of Earth, explaining their role in weather and climate Features current research examples and case studies, including those on advanced research methods from authors with experience in both academia and the industry Discusses the latest advances in this subject area, providing the reader with access to best practices for remote sensing and numerical modeling
Author: Alexander Marshak Publisher: Springer Science & Business Media ISBN: 3540285199 Category : Science Languages : en Pages : 688
Book Description
Developments in three-dimensional cloud radiation over the past few decades are assessed and distilled into this contributed volume. Chapters are authored by subject-matter experts who address a broad audience of graduate students, researchers, and anyone interested in cloud-radiation processes in the solar and infrared spectral regions. After two introductory chapters and a section on the fundamental physics and computational techniques, the volume extensively treats two main application areas: the impact of clouds on the Earth's radiation budget, which is an essential aspect of climate modeling; and remote observation of clouds, especially with the advanced sensors on current and future satellite missions.
Author: Yong-Keun Lee
Author: Yong-Keun Lee
Author: Bruce Anthony Wielicki
Author: Gary E. Thomas
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Author: Kuo-Nan Liou
Author: Peter Hobbs
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Author: 
Author: Constantin Andronache
Author: Alexander Marshak