Cirrus Microphysical Properties From Stellar Aureole Measurements Phase I
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| Release | : 2012 |
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While knowledge of the impact of aerosols on climate change has improved significantly due to the routine, ground-based, sun photometer measurements of aerosols made at AERONET sites world-wide, the impact of cirrus clouds remains much less certain because they occur high in the atmosphere and are more difficult to measure. This report documents work performed on a Phase I SBIR project to retrieve microphysical properties of cirrus ice crystals from stellar aureole imagery. The Phase I work demonstrates that (1) we have clearly measured stellar aureole profiles; (2) we can follow the aureole profiles out to 1̃/4 degree from stars (1̃/2 degree from Jupiter); (3) the stellar aureoles from cirrus have very distinctive profiles, being flat out to a critical angle, followed by a steep power-law decline with a slope of -̃3; (4) the profiles are well modeled using exponential size distributions; and (5) the critical angle in the profiles is 0̃.12 degrees, (6) indicating that the corresponding critical size ranges from 1̃50 to 2̃00 microns. The stage has been set for a Phase II project (1) to proceed to validating the use of stellar aureole measurements for retrieving cirrus particle size distributions using comparisons with optical property retrievals from other, ground-based instruments and (2) to develop an instrument for the routine, automatic measurement of thin cirrus microphysical properties.
| Author | : David K. Lynch |
| Publisher | : Oxford University Press, USA |
| Total Pages | : 499 |
| Release | : 2002 |
| Genre | : Cirrus clouds |
| ISBN | : 0195130723 |
This text, devoted entirely to cirrus clouds, captures the state of knowledge of cirrus clouds and serves as a practical handbook as well.
| Author | : Chenxi Wang |
| Publisher | : |
| Total Pages | : 180 |
| Release | : 2013 |
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This dissertation focuses on the global investigation of optically thin cirrus cloud optical thickness [tau] and microphysical properties, such as, effective particle size (D_(eff)) and ice crystal habits (shapes), based on the global satellite observations and fast radiative transfer models (RTMs). In the first part, we develop two computationally efficient RTMs simulating satellite observations under cloudy-sky conditions in the visible/shortwave infrared (VIS/SWIR) and thermal inferred (IR) spectral regions, respectively. To mitigate the computational burden associated with absorption, thermal emission and multiple scattering, we generate pre-computed lookup tables (LUTs) using two rigorous models, i.e., the line-by-line radiative transfer model (LBLRTM) and the discrete ordinates radiative transfer model (DISORT). The second part introduces two methods (i.e., VIS/SWIR- and IR-based methods) to retrieve [tau] and D_(eff) from satellite observations in corresponding spectral regions of the two RTMs. We discuss the advantages and weakness of the two methods by estimating the impacts from different error sources on the retrievals through sensitivity studies. Finally, we develop a new method to infer the scattering phase functions of optically thin cirrus clouds in a water vapor absorption channel (1.38-[mu]m). We estimate the ice crystal habits and surface structures by comparing the inferred scattering phase functions and numerically simulated phase functions calculated using idealized habits. We find two critical features of the two retrieval methods: (1) the IR-based method is more sensitive to optically thin cirrus cloud, and (2) the VIS/SWIR-based method is more sensitive to the pre-assumed ice cloud microphysical parameterization schemes. We derive the optically thin cirrus cloud phase functions based on the two methods. We find that small column-like particles (e.g., solid columns and column-aggregates) and droxtals with rough surfaces are likely to reside in optically thin cirrus clouds. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151213
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| Release | : 2001 |
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The main work activity during this period was the refinement and GCM parameterization of the treatment of ice cloud radiative properties, developed for this project. The treatment has now been rigorously tested and improved, and can now be used with confidence in radiation transfer schemes. The ice Cloud radiation scheme has also proven useful in satellite remote sensing. The radiation scheme differs from others in the thermal infrared, where it is assumed that photon tunneling does not occur for real ice particles (tunneling can be viewed as a process by which photons outside a particle's area-cross section can still be absorbed). Single particle T-matrix and Mie calculations suggest that a particle's ability to capture energy through tunneling depends on surface morphology, with more tunneling the more circular (or less angular) a surface is. This assumption leads to retrievals of mean particle size which are similar to those observed in tropical cirrus by optical imaging probes, whereas retrieved sizes using Mie theory are about 1/3 those predicted by this scheme. The retrieval method requires channels in the 8--9[micro]m and 11--12[micro]m ranges. This assumption about tunneling, as well as treating size distributions in the radiation scheme as bimodal, allows retrievals over a broader range of mean particle size than previous schemes permitted, making such size retrievals applicable to most types of cirrus clouds.
| Author | : Alexander A. Kokhanovsky |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 154 |
| Release | : 2008-03-18 |
| Genre | : Science |
| ISBN | : 3540499091 |
This new text offers experienced students a comprehensive review of available techniques for the remote sensing of aerosols. These small particles influence both atmospheric visibility and the thermodynamics of the atmosphere. They are also of great importance in any consideration of climate change problems. Aerosols may also be responsible for the loss of harvests, human health problems and ecological disasters. Thus, this detailed study of aerosol properties on a global scale could not be more timely.
| Author | : Johan H. Knapen |
| Publisher | : Springer |
| Total Pages | : 367 |
| Release | : 2017-07-09 |
| Genre | : Science |
| ISBN | : 3319565702 |
This book consists of invited reviews written by world-renowned experts on the subject of the outskirts of galaxies, an upcoming field which has been understudied so far. These regions are faint and hard to observe, yet hide a tremendous amount of information on the origin and early evolution of galaxies. They thus allow astronomers to address some of the most topical problems, such as gaseous and satellite accretion, radial migration, and merging. The book is published in conjunction with the celebration of the end of the four-year DAGAL project, an EU-funded initial training network, and with a major international conference on the topic held in March 2016 in Toledo. It thus reflects not only the views of the experts, but also the scientific discussions and progress achieved during the project and the meeting. The reviews in the book describe the most modern observations of the outer regions of our own Galaxy, and of galaxies in the local and high-redshift Universe. They tackle disks, haloes, streams, and accretion as observed through deep imaging and spectroscopy, and guide the reader through the various formation and evolution scenarios for galaxies. The reviews focus on the major open questions in the field, and explore how they can be tackled in the future. This book provides a unique entry point into the field for graduate students and non-specialists, and serves as a reference work for researchers in this exciting new field.
| Author | : K. Shmulovich |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 348 |
| Release | : 1994-12-31 |
| Genre | : Science |
| ISBN | : 9780412563201 |
For much of the 20th century, scientific contacts between the Soviet Union and western countries were few and far between, and often super ficial. In earth sciences, ideas and data were slow to cross the Iron Curtain, and there was considerable mutual mistrust of diverging scient ific philosophies. In geochemistry, most western scientists were slow to appreciate the advances being made in the Soviet Union by os. Korz hinskii, who put the study of ore genesis on a rigorous thermodynamic basis as early as the 1930s. Korzhinskii appreciated that the most fun damental requirement for the application of quantitative models is data on mineral and fluid behaviour at the elevated pressures and temper atures that occur in the Earth's crust. He began the work at the Institute of Experimental Mineralogy (IEM) in 1965, and it became a separate establishment of the Academy of Sciences in Chernogolovka in 1969. The aim was to initiate a major programme of high P-T experimental studies to apply physical chemistry and thermodynamics to resolving geological problems. For many years, Chernogolovka was a closed city, and western scient ists were unable to visit the laboratories, but with the advent of peres troika in 1989, the first groups of visitors were eagerly welcomed to the IEM. What they found was an experimental facility on a massive scale, with 300 staff, including 80 researchers and most of the rest pro viding technical support.
| Author | : William E. Sharp |
| Publisher | : |
| Total Pages | : 12 |
| Release | : 1966 |
| Genre | : Sky |
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| Author | : Gary E. Thomas |
| Publisher | : Cambridge University Press |
| Total Pages | : 554 |
| Release | : 2002-01-28 |
| Genre | : Nature |
| ISBN | : 9780521890618 |
Provides a foundation of the theoretical and practical aspects of radiative transfer, for the atmospheric, oceanic and environmental sciences.
| Author | : National Aeronautics and Space Adm Nasa |
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| Total Pages | : 48 |
| Release | : 2018-11 |
| Genre | : |
| ISBN | : 9781729394434 |
The contributions of complex rays and the secondary radiation shed by surface waves to scattering by a dielectric sphere are calculated in the context of the Debye series expansion of the Mie scattering amplitudes. Also, the contributions of geometrical rays are reviewed and compared with the Debye series. Interference effects between surface waves, complex waves, and geometrical waves are calculated, and the possibility of observing these interference effects is discussed. Experimental data supporting the observation of a surface wave-geometrical pattern is presented. Hovenac, Edward A. and Lock, James A. Unspecified Center NAS3-25266; RTOP 505-62-00...
