Download or read book Radar Measurements and Simulations of Ice Crystal Growth in Arctic Mixed phase Clouds written by Robert Stephen Schrom and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Polarimetric radar measurements offer the potential to better understand the microphysical processes in cloud and precipitation systems. The large uncertainties in current microphysical theories and corresponding numerical models of the ice growth processes suggest a natural area where these measurements can yield large benefits. However, these uncertainties make interpretations of a given set of radar observations ambiguous. Additionally, understanding the theoretical framework behind the scattering of individual ice particles, as well as the bulk signal of a population of ice particles, is necessary to fully make use of polarimetric radar observations.Given a particular set of ice crystal physical properties, there is still uncertainty in their scattering properties. The homogeneous, reduced-density simplification for the structure of branched planar crystals is shown to produce large errors in their scattering properties. The reduced-density representations underestimatethe ZDR and KDP of individual ice crystals due to their inability to represent the distribution of mass within the particles, and the importance this distribution has on the electric-field interactions between dipoles comprising the particle.To more accurately map simple physical properties of branched planar crystals such as maximum dimension, aspect ratio, and effective density to their scattering properties, a set of electromagnetic scattering calculations for a range of realistic particle shapes were performed. The resulting scattering properties were then fit to the physical properties using polynomials; for long wavelengths (i.e., at frequencies above Ku-band), Rayleigh theory was used to determine representative scattering properties of the branched planar crystals through the use of equivalent-scattering solid-ice spheroids. These equivalent spheroids are therefore are valid at all wavelengths large relative to the maximum dimension. Using this mapping procedure, a forward model was then developed for the polarimetric radar signaturesof populations of branched planar crystals.The ambiguity in the ice crystal structure given a particular effective density leads to an inherent uncertainty in the resulting forward-simulated radar variables. This uncertainty in the forward model was accounted for by perturbing the dimensions of the equivalent-solid ice spheroids associated with a given set of physicalproperties, and using these perturbations to generate a certain number of realizations of forward-simulated radar variables. These uncertainties are largest for particles with the lowest aspect ratios and lowest effective densities, and therefore the forward model uncertainty depends on the specific distribution of ice crystal physical properties. In comparison to the spatial variability of radar observations during an Arctic mixed-phase cloud case, the forward model uncertainty is relatively low, suggesting the importance in accurately characterizing the growth environment and properly constraining the assumptions about the spectra of ice particle properties associated with the given set of radar observations. In order to better interpret radar measurements of planar crystal growth in an Arctic mixed-phase cloud, where polarimetric radar observations were collected by the ARM XSAPR in Barrow, AK, the radar forward model was coupled to a bin microphysical model of vapor depositional growth. The microphysical model is driven by a simplified 2-D kinematic model with idealized updraft and downdraft cells. Given the uncertainties in the properties of these updrafts, an ensemble of simulations with different perturbations for the updraft characteristics and the ice particle concentration was created and analyzed. In addition, a new formulation for the deposition density associated with vapor growth was implemented in the model. This new deposition density is based on the shape generation procedure for the scattering calculations and therefore more realistically captures the evolution of natural branched planar crystal structures. Given the uncertainties in these ice crystal structures, the structural quantities in the deposition density formulation were also perturbed in the ensemble.The resulting simulations were able to capture the general features of the observed radar profiles, with comparable values of ZH and ZDR . However, none of the simulations produced the observed decrease in ZDR from the top to the bottom of the profile, likely due to the differential sedimentation of hydrometeors or the lack of aggregation in the model. The simulations that fell within the variability of the observations suggested two general interpretations: one with a higher concentration of ice particles, smaller sizes, and higher densities, and another with lower concentration of ice particles, larger sizes, and lower densities. These two clusters produced KDP profiles with vastly different magnitudes; lower and higher magnitudes were observed with the low- and high-concentration clusters.Given the ubiquity of aggregation and riming in Arctic clouds, the potential for radar measurements to inform the understanding of this processes is discussed. The use of observations from multiple cases and the addition of multi-frequency observations is also likely to further improve the understanding of ice growth processes in cloud and precipitation systems.
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 Simulating Mixed phase Arctic Stratus Clouds written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during October 9th-10th, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-hour simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and subsaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.
Download or read book Simulating Mixed phase Arctic Stratus Clouds written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during 9th-10th October, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-h simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and undersaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.
Download or read book Light Scattering by Ice Crystals written by Kuo-Nan Liou and published by Cambridge University Press. This book was released on 2016-10-06 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume outlines the fundamentals and applications of light scattering, absorption and polarization processes involving ice crystals.
Download or read book Ice Formation and Evolution in Clouds and Precipitation written by Darrel Baumgardner and published by . This book was released on 2018-03-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Ice crystals, with their myriad shapes, sizes and densities, play an important role in the formation, evolution and subsequent impact of ice and mixed-phase clouds on weather and climate. There are numerous pathways through which ice crystals nucleate, grow and dissipate. Although many of these are understood theoretically and have been simulated in the laboratory and cloud chambers, they are less well documented in natural clouds. The challenges of making measurements from moving platforms in an environment that is spatially inhomogenous and temporally unsteady, as well as sometimes at high altitudes and in clouds with icing potential makes these clouds difficult to observe. Nevertheless, the importance of ice clouds on climate and the hydrological cycle compels us to better understand ice processes through improved measurements over as broad of a temporal and geographical scale as possible. This monograph represents a collection of articles that do exactly that."-- Book jacket.
Download or read book Shape temperature Relationship of Ice Crystals in Mixed phase Clouds Based on Observations with Polarimetric Cloud Radar written by Alexander Myagkov and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unique Ice Crystal Observations from the ICE Ball Field Campaign Combined with Model Simulations Elucidate Cirrus Development written by Marley Majetic and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cirrus clouds are ubiquitous over large spatial domains on Earth, yet the detailed morphology of the small ice crystals that compose these clouds is not well understood. Ice crystal surface structure influences crystal growth rates and radiative properties that can have either a positive or negative contribution to climatic warming. This work provides new observations of small cirrus particles collected during the Ice Cryo Encapsulation by Balloon (ICE-Ball) campaign that took place in Oklahoma for three weeks during the fall of 2021. Scanning Electron Microscope (SEM) images of crystals exhibit the frequent occurrence of complex polycrystalline habits, such as scroll rosettes, and frequent hollowing of small ice crystals, suggesting that faceting instability occurs on crystals with dimensions as small as 20 [mu]m. These results indicate that the effective density of small crystals may be less than prior in-situ estimates. Backward and forward trajectory calculations using the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) are used together with meteorological characterization based on ERA5 reanalysis to analyze the background airmass characteristics in which the observed cirrus formed. These analyses provide forcing for one-dimensional model simulations of a cirrus case that occurred on October 23rd, 2021; scroll rosettes were the dominant habit sampled. Laboratory measurements of rosette growth are used to inform model microphysics, thereby facilitating a more accurate depiction of the vapor depositional growth of cirrus crystals. These model simulations, in conjunction with the ICE-Ball in-situ samples, vertically pointing radar and lidar measurements, satellite observations, and reanalysis data, are used to estimate the spatiotemporal extent and lifetime of the cirrus cloud field observed on October 23rd, 2021, contributing to the understanding of ice crystal morphological development and the associated environmental feedbacks.
Download or read book Shape temperature Relationship of Ice Crystals in Mixed phase Clouds Based on Observations with Polarimetric Cloud Radar written by Alexander Myagkov and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fast Processes in Large Scale Atmospheric Models written by Yangang Liu and published by John Wiley & Sons. This book was released on 2023-12-11 with total page 483 pages. Available in PDF, EPUB and Kindle. Book excerpt: Improving weather and climate prediction with better representation of fast processes in atmospheric models Many atmospheric processes that influence Earth’s weather and climate occur at spatiotemporal scales that are too small to be resolved in large scale models. They must be parameterized, which means approximately representing them by variables that can be resolved by model grids. Fast Processes in Large-Scale Atmospheric Models: Progress, Challenges and Opportunities explores ways to better investigate and represent multiple parameterized processes in models and thus improve their ability to make accurate climate and weather predictions. Volume highlights include: Historical development of the parameterization of fast processes in numerical models Different types of major sub-grid processes and their parameterizations Efforts to unify the treatment of individual processes and their interactions Top-down versus bottom-up approaches across multiple scales Measurement techniques, observational studies, and frameworks for model evaluation Emerging challenges, new opportunities, and future research directions The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Download or read book Snow Crystals written by Kenneth G. Libbrecht and published by Princeton University Press. This book was released on 2021-12-21 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Despite substantial, cross-disciplinary interest in the subject as a scientific case study, surprisingly little has been written on the science of snowflakes and their formation. For materials scientists, snowflakes constitute archetypal examples of crystal growth; for chemists, the site of complex molecular dynamics at the ice surface. Physicists can learn from snowflake symmetry and self-assembly; geologists study snow as mineral crystals; and biologists can even gain insight into the creation of shape and order in organisms. In the humble snowflake are condensed many of the processes-many of them still not fully understood-that govern the organization of classical systems at all levels of the natural world. This book by Kenneth Libbrecht-inarguably the world's foremost expert on the subject-will be the authoritative text on the science of snow crystals. It will cover all of the physical processes that govern the life of a snowflake, including how snowflakes grow and why they have the shapes they do. It will also outline techniques for creating and experimenting with snow crystals, both with computer models and in the lab. Featuring hundreds of color illustrations, the book will be comprehensive and is sure to become definitive resource for researchers for years, if not decades, to come"--
Download or read book Cloud Dynamics written by PRUPPACHER and published by Birkhäuser. This book was released on 1976 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Growth of Ice Crystals by Diffusion in Mixed Phase Clouds written by Kiran Sonnad and published by . This book was released on 1998 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radar Polarimetry for Weather Observations written by Alexander V. Ryzhkov and published by Springer. This book was released on 2019-03-25 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph offers a wide array of contemporary information on weather radar polarimetry and its applications. The book tightly connects the microphysical processes responsible for the development and evolution of the clouds’ bulk physical properties to the polarimetric variables, and contains the procedures on how to simulate realistic polarimetric variables. With up-to-date polarimetric methodologies and applications, the book will appeal to practicing radar meteorologists, hydrologists, microphysicists, and modelers who are interested in the bulk properties of hydrometeors and quantification of these with the goals to improve precipitation measurements, understanding of precipitation processes, or model forecasts.
Download or read book Polarimetric Doppler Weather Radar written by V. N. Bringi and published by Cambridge University Press. This book was released on 2001-08-30 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 2001 book provides a detailed introduction to the principles of Doppler and polarimetric radar, focusing in particular on their use in the analysis of weather systems. The design features and operation of practical radar systems are highlighted throughout the book in order to illustrate important theoretical foundations. The authors begin by discussing background topics such as electromagnetic scattering, polarization, and wave propagation. They then deal in detail with the engineering aspects of pulsed Doppler polarimetric radar, including the relevant signal theory, spectral estimation techniques, and noise considerations. They close by examining a range of key applications in meteorology and remote sensing. The book will be of great use to graduate students of electrical engineering and atmospheric science as well as to practitioners involved in the applications of polarimetric radar systems.
Download or read book Snow and Climate written by Richard L. Armstrong and published by Cambridge University Press. This book was released on 2008-04-24 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the prevailing state of snow-climate science for researchers and advanced students.
Download or read book An Introduction to Clouds written by Ulrike Lohmann and published by Cambridge University Press. This book was released on 2016-06-23 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: An Introduction to Clouds provides a fundamental understanding of clouds, ranging from cloud microphysics to the large-scale impacts of clouds on climate. On the microscale, phase changes and ice nucleation are covered comprehensively, including aerosol particles and thermodynamics relevant for the formation of clouds and precipitation. At larger scales, cloud dynamics, mid-latitude storms and tropical cyclones are discussed leading to the role of clouds on the hydrological cycle and climate. Each chapter ends with problem sets and multiple-choice questions that can be completed online, and important equations are highlighted in boxes for ease of reference. Combining mathematical formulations with qualitative explanations of underlying concepts, this accessible book requires relatively little previous knowledge, making it ideal for advanced undergraduate and graduate students in atmospheric science, environmental sciences and related disciplines.
