Download or read book Studying Clouds and Aerosols with Lidar Depolarization Ratio and Backscatter Relationships written by Hyoun-Myoung Cho and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation consists of three parts, each devoted to a particular issue of significant importance for CALIPSO lidar observation of depolarization ratio (delta) and backscatter (gamma?) to improve current understanding of the microphysical properties of clouds and aerosols. The relationships between depolarization ratio and backscatter allow us to retrieve particle thermodynamic phase and shape and/or orientation of aerosols and clouds. The first part is devoted to the investigation of the relationships between lidar backscatter and the corresponding depolarization ratio for different cloud classifications and aerosol types. For each cloud and aerosol types, layer-averaged backscatter and backscattering depolarization ratio from the CALIPSO measurements are discussed. The present results demonstrate the unique capabilities of the CALIPSO lidar instrument for determining cloud phase and aerosols subtypes. In the second part, we evaluate the MODIS IR cloud phase with the CALIPSO cloud products. The three possible misclassifications of MODIS IR cloud phasealgorithm, which are studied by Nasiri and Kahn (2008) with radiative transfer modeling, are tested by comparing between MODIS IR phase and CALIOP observations. The current results support their hypotheses, which is that the MODIS phase algorithm may tend to classify thin cirrus clouds as water clouds or mixed phase clouds or unknown, and classify midlevel and/or mid-temperature clouds as mixed or unknown phase. In the third part, we present a comparison of mineral dust aerosol retrievals from two instruments, MODIS and CALIPSO lidar. And, we implement and evaluate a new mineral dust detection algorithm based on the analysis of thin dust radiative signature. In comparison, three commonly used visible and IR mineral dust detection algorithms, including BTD procedure, D parameter method, and multi-channel image algorithm, are evaluated with CALIPSO aerosol classification. The comparison reveals that those dust detection algorithms are not effective for optically thin dust layers, but for thick dust storm. The new algorithm using discriminant analysis with CALIPSO observation is much better in detecting thin dust layer of optical thickness between 0.1 and 2.
Download or read book Opportunities to Improve Representation of Clouds and Aerosols in Climate Models with Classified Observing Systems written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2016-08-31 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most significant and uncertain aspects of climate change projections is the impact of aerosols on the climate system. Aerosols influence the climate indirectly by interacting with nearby clouds leading to small changes in cloud cover, thickness, and altitude, which significantly affect Earth's radiative balance. Advancements have been made in recent years on understanding the complex processes and atmospheric interactions involved when aerosols interact with surrounding clouds, but further progress has been hindered by limited observations. The National Academies of Sciences, Engineering, and Medicine organized a workshop to discuss the usefulness of the classified observing systems in advancing understanding of cloud and aerosol interactions. Because these systems were not developed with weather and climate modeling as a primary mission objective, many participants said it is necessary for scientists to find creative ways to utilize the data. The data from these systems have the potential to be useful in advancing understanding of cloud and aerosol interactions. This publication summarizes the presentations and discussions from the workshop.
Download or read book A Basic Comparison of Lidar and Radar for Remote Sensing of Clouds written by Vernon Ellsworth Derr and published by . This book was released on 1978 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Both radar and lidar have proved valuable in studying cloud microphysics and dynamics. Because of the large difference in wavelength, the two techniques have differing penetration capabilities and detection sensitivities. A "system-free" comparison of radar and lidar for several missions and many cloud types is presented to permit the optimum choice of technique for field studies of cloud formation, development, and precipitation.
Download or read book Advances in Atmospheric Remote Sensing with Lidar written by Albert Ansmann and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 603 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lidar or laser radar, the depth-resolved remote measurement of atmospheric parameters with optical means, has become an important tool in the field of atmospheric and environmental remote sensing. In this volume the latest progress in the development of Lidar methods, experiments, and applications is described. The content is based on selected and thoroughly refereed papers presented at the 18th International Laser Radar Conference, Berlin, 22 - 26 July 1996. The book is divided into six parts which cover the topics of tropospheric aerosols and clouds, Lidar in space, wind, water vapor, troposheric trace gases and plumes, and stratospheric and mesospheric profiling. As a supplement to fundamental LIDAR textbooks this volume may serve as a guide through the blossoming field of modern Lidar techniques.
Download or read book Feasibility of monitoring aerosol concentrations by 10 6 um backscatter lidar written by Gordon Lerfald and published by . This book was released on 1977 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerosol Cloud Interactions from Urban Regional to Global Scales written by Yuan Wang and published by Springer. This book was released on 2015-05-05 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: The studies in this dissertation aim at advancing our scientific understandings about physical processes involved in the aerosol-cloud-precipitation interaction and quantitatively assessing the impacts of aerosols on the cloud systems with diverse scales over the globe on the basis of the observational data analysis and various modeling studies. As recognized in the Fifth Assessment Report by the Inter-government Panel on Climate Change, the magnitude of radiative forcing by atmospheric aerosols is highly uncertain, representing the largest uncertainty in projections of future climate by anthropogenic activities. By using a newly implemented cloud microphysical scheme in the cloud-resolving model, the thesis assesses aerosol-cloud interaction for distinct weather systems, ranging from individual cumulus to mesoscale convective systems. This thesis also introduces a novel hierarchical modeling approach that solves a long outstanding mismatch between simulations by regional weather models and global climate models in the climate modeling community. More importantly, the thesis provides key scientific solutions to several challenging questions in climate science, including the global impacts of the Asian pollution. As scientists wrestle with the complexities of climate change in response to varied anthropogenic forcing, perhaps no problem is more challenging than the understanding of the impacts of atmospheric aerosols from air pollution on clouds and the global circulation.
Download or read book Lidar Observations of Natural and Volcanic ash induced Cirrus Clouds written by Christian Rolf and published by Forschungszentrum Jülich. This book was released on 2013 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Relationships Between Lidar Aerosol Extinction and Backscatter Coefficients with CCN Number Concentrations in the Southeast Atlantic written by Emily Lenhardt and published by . This book was released on 2021 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Backscatter Laser Depolarization Studies of Simulated Stratospheric Aerosols written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystallization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds. Sassen, Kenneth and Zhao, Hongjie and Yu, Bing-Kun Unspecified Center NASA-CR-183387, NAS 1.26:183387 NAG1-686...
Download or read book Aerosol cloud climate Interactions written by Peter Victor Hobbs and published by . This book was released on 1993 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol and clouds play important roles in determining the earth's climate, in ways that we are only beginning to comprehend. In conjunction with molecular scattering from gases, aerosols, and clouds determine in part what fraction of solar radiation reaches the earth's surface and what fraction of the longwave radiation from the earth escapes to space. This book provides an overview of the latest. research on atmospheric aerosols and clouds and their effects on global climate
Download or read book Improved Simulation of Aerosol Cloud and Density Measurements by Shuttle Lidar written by and published by . This book was released on 1981 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monte Carlo Simulation of Detection of Cirrus Cloud Properties by Micro Pulse Lidar written by James A. Cotturone and published by . This book was released on 1996-05-01 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of the Micro Pulse Lidar (MPL) provides researchers with a system capable of continuous, eye-safe monitoring of atmospheric properties. The MPL operates with low energy, high pulse repetition frequency radiation in the visible portion of the spectrum. To investigate the interaction between visible radiation and atmospheric constituents, a model using Monte Carlo techniques has been refined to simulate MPL return profiles. An inherent feature of the MPL is its narrow receiver field of view (FOV) which is necessary to limit background noise. The effect of such a FOV and the role multiple scattering effects play in MPL operations are investigated in this study. Cloud base height and the radiative properties of cirrus clouds are important for determining the radiation budget of the planet. Inferred cirrus cloud radiative properties vary with the type of crystals assumed to compose the model clouds. To properly model optically thin clouds, it is important to include a standard background atmosphere composed of Rayleigh and aerosol scatterers. Its inclusion allows one to take advantage of information deduced from both the cloud and above-cloud layer. Information that is unavailable when sampling optically thick clouds. This capability plays a pivotal role in an inversion algorithm that is developed and described. It is shown that the algorithm allows one to infer important cloud optical properties such as volume extinction coefficient, cloud optical depth, and isotropic backscatter to extinction ratio, also known as the lidar ratio.
Download or read book Classification of Polar Stratospheric Clouds Using LIDAR Measurements From the SAGE III Ozone Loss and Validation Experiment written by and published by . This book was released on 2007 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Backscatter LIDAR measurements from the stratospheric aerosol and gas experiment (SAGE) III ozone loss and validation experiment (SOLVE) have been used to identify classes of polar stratospheric clouds (PSCs) and their corresponding characteristics. Volume backscatter at 532 nm (Beta532) and 1064 nm (Beta1064), scattering ratio at 532 nm (R532) and 1064 nm (R1064), aerosol depolarization (delta(a)), and color ratio (Beta532/Beta1064), and temperature (T) were used to categorize PSCs via principal component analysis (PCA) and Cluster Analysis (CA). The clusters found in this study are consistent with previous studies of PSCs of types Ia (R532 1.5 and delta(a) 0.1), Ia-enhanced (R532> 1.4 and delta(a)> 0.1), Ib (R532> 2 and delta(a) 0.025), and II (532 7 and delta(a)> 0.1). In addition, a cluster predominantly found on the outside edges of clouds, which does not fit the definition of these PSCs, which has low R532 and delta(a) values, was found. The clustering analysis of PSC data provides an objective and automated method for the production of image plots that show a two-dimensional distribution of the PSC particle types. Such capabilities will be useful for analyzing large data sets such as will be produced by space-borne LIDARS (laser identification and ranging system).
Download or read book Study on Multi layer aerosol Situations and of aerosol cloud Interactions written by Lucia-Timea Deaconu and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the main objectives of this study is to analyze the consistency between the aerosol above clouds (AAC) retrievals from passive and active satellite measurements. We consider the method based on the passive polarization measurements provided by the POLDER instrument, the operational method developed for the space borne lidar CALIOP, and the CALIOP-based depolarization ratio method (DRM), for which we also propose a calibrated version. We perform a regional analysis and a global multi-annual analysis to provide robust statistics results. Our findings show good agreement between DRM and POLDER AOT retrievals (R2=0.68 at global scale). This result gives confidence in our ability to measure the properties of AAC. Differences occur when the aerosol and cloud layers are in contact. CALIOP operational method is largely underestimating the above cloud AOT, compared to the other two methods.The second objective is to study the impact of aerosols on the cloud properties and their radiative forcing, over the South Atlantic Ocean. We perform a synergy between CALIOP vertical profiles and POLDER retrievals, with collocated meteorological parameters. We performed radiative transfer calculations in the short- and longwave domains, and analyzed the effect of aerosol loading on the cloud properties and meteorology. We found that aerosols and water vapor effects could impact the cloud convection. Our results show that under large loads of AACs, clouds become optically thicker, with an increase in liquid water path of 20 g.m-2 and their cloud top altitudes are lower by 200 m, which may indicate a potential semi-direct effect of aerosols above clouds.
Download or read book Lidar Technologies Techniques and Measurements for Atmospheric Remote Sensing XII written by Upendra N. Singh and published by . This book was released on 2017-02-28 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of SPIE present the original research papers presented at SPIE conferences and other high-quality conferences in the broad-ranging fields of optics and photonics. These books provide prompt access to the latest innovations in research and technology in their respective fields. Proceedings of SPIE are among the most cited references in patent literature.
Download or read book Mixed Phase Clouds written by Constantin Andronache and published by Elsevier. This book was released on 2017-09-28 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book A Plan for a Research Program on Aerosol Radiative Forcing and Climate Change written by Panel on Aerosol Radiative Forcing and Climate Change and published by National Academies Press. This book was released on 1996-05-01 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book recommends the initiation of an "integrated" research program to study the role of aerosols in the predicted global climate change. Current understanding suggest that, even now, aerosols, primarily from anthropogenic sources, may be reducing the rate of warming caused by greenhouse gas emissions. In addition to specific research recommendations, this book forcefully argues for two kinds of research program integration: integration of the individual laboratory, field, and theoretical research activities and an integrated management structure that involves all of the concerned federal agencies.
