Download or read book Turbulence and Life Time Studies of Shallow Cumuli Clouds Using Scanning Cloud Radar Observations written by Paloma Borque and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Les nuages jouent un rôle critique dans le système climatique terrestre. L'étude des éléments de nuage lors de leur transition à travers diverses étapes de leur cycle de vie est donc d'une importance vitale. Le suivi des nuages à l'aide des radars de nuage à balayage peut aider à documenter l'évolution temporelle des propriétés de nuages bien avant la formation des grosses gouttes (le premier écho radar). Un nouvel algorithme d'identification et de suivi (CITA) est développé pour faire le suivi des éléments de nuages à partir d'observations verticales dans le sens des vents d'une population the cumulus peu profonds (avec et sans précipitation). Basé sur le CITA, l'évolution temporelle des propriétés des éléments de nuage (nombre, taille, réflectivité maximale) et leur connexion avec l'environnement peuvent être analysées. La turbulence affecte fortement le cycle de vie des nuages, surtout leurs stages de formation et de dissipation. Des observations coïncidentes de profilage d'un lidar Doppler et de radars sont utilisées pour estimer la vitesse de dissipation de l'énergie turbulente ([epsilon]) à partir de différentes sources de données: vitesse Doppler radar, vitesse Doppler lidar et les mesures de largeur spectrale de radar Doppler. Les évaluations de vitesse de dissipation de turbulence basées sur les mesures de vitesse Doppler sont consistantes lors des conditions de bruine mais aussi en leur absence, suggérant que la vitesse de dissipation de tourbillon peut être estimée à travers la couche de nuage sans contrainte quant à la présence de précipitation. Par contre, l'utilisation des séries temporelles de vélocité Doppler radar et lidar pour mesurer [epsilon] requierent de longues périodes (~20 minutes) d'observations continues. Étant donné la courte durée de vie des nuages cumulus (3-10 minutes selon les radars nuages à profilage) ces techniques sont surtout limitées au nuages stratiformes. Cela motive le travail exploratoire sur une nouvelle technique basée sur les observations à double longueur d'onde pour estimer la vitesse de dissipation des tourbillons de nuages de courte durée." --

Download or read book First Observations of Tracking Clouds Using Scanning ARM Cloud Radars written by and published by . This book was released on 2014 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tracking clouds using scanning cloud radars can help to document the temporal evolution of cloud properties well before large drop formation (''first echo''). These measurements complement cloud and precipitation tracking using geostationary satellites and weather radars. Here, two-dimensional (2-D) Along-Wind Range Height Indicator (AW-RHI) observations of a population of shallow cumuli (with and without precipitation) from the 35-GHz scanning ARM cloud radar (SACR) at the DOE Atmospheric Radiation Measurements (ARM) program Southern Great Plains (SGP) site are presented. Observations from the ARM SGP network of scanning precipitation radars are used to provide the larger scale context of the cloud field and to highlight the advantages of the SACR to detect the numerous, small, non-precipitating cloud elements. A new Cloud Identification and Tracking Algorithm (CITA) is developed to track cloud elements. In CITA, a cloud element is identified as a region having a contiguous set of pixels exceeding a preset reflectivity and size threshold. The high temporal resolution of the SACR 2-D observations (30 sec) allows for an area superposition criteria algorithm to match cloud elements at consecutive times. Following CITA, the temporal evolution of cloud element properties (number, size, and maximum reflectivity) is presented. The vast majority of the designated elements during this cumulus event were short-lived non-precipitating clouds having an apparent life cycle shorter than 15 minutes. The advantages and disadvantages of cloud tracking using an SACR are discussed.

Download or read book Mesoscale Meteorology in Midlatitudes written by Paul Markowski and published by John Wiley & Sons. This book was released on 2011-09-20 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mesoscale Meteorology in Mid-Latitudes presents the dynamics of mesoscale meteorological phenomena in a highly accessible, student-friendly manner. The book's clear mathematical treatments are complemented by high-quality photographs and illustrations. Comprehensive coverage of subjects including boundary layer mesoscale phenomena, orographic phenomena and deep convection is brought together with the latest developments in the field to provide an invaluable resource for mesoscale meteorology students. Mesoscale Meteorology in Mid-Latitudes functions as a comprehensive, easy-to-use undergraduate textbook while also providing a useful reference for graduate students, research scientists and weather industry professionals. Illustrated in full colour throughout Covers the latest developments and research in the field Comprehensive coverage of deep convection and its initiation Uses real life examples of phenomena taken from broad geographical areas to demonstrate the practical aspects of the science

Download or read book Collaborative Research written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a collaborative project with Dr. Ping Zhu at Florida International University. It was designed to address key issues regarding the treatment of boundary layer cloud processes in climate models with UM's research focusing on the analyses of ARM cloud radar observations from MMCR and WACR and FIU's research focusing on numerical simulations of boundary layer clouds. This project capitalized on recent advancements in the ARM Millimeter Cloud Radar (MMCR) processing and the development of the WACR (at the SGP) to provide high temporal and spatial resolution Doppler cloud radar measurements for characterizing in-cloud turbulence, large-eddy circulations, and high resolution cloud structures of direct relevance to high resolution numerical modeling studies. The principal focus of the observational component of this collaborative study during this funding period was on stratocumulus clouds over the SGP site and fair-weather cumuli over the Nauru site. The statistical descriptions of the vertical velocity structures in continental stratocumulus clouds and in the Nauru shallow cumuli that are part of this study represents the most comprehensive observations of the vertical velocities in boundary layer clouds to date and were done in collaboration with Drs. Virendra Ghate and Pavlos Kollias.

Download or read book Observing Weather and Climate from the Ground Up written by National Research Council and published by National Academies Press. This book was released on 2009-01-06 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed weather observations on local and regional levels are essential to a range of needs from forecasting tornadoes to making decisions that affect energy security, public health and safety, transportation, agriculture and all of our economic interests. As technological capabilities have become increasingly affordable, businesses, state and local governments, and individual weather enthusiasts have set up observing systems throughout the United States. However, because there is no national network tying many of these systems together, data collection methods are inconsistent and public accessibility is limited. This book identifies short-term and long-term goals for federal government sponsors and other public and private partners in establishing a coordinated nationwide "network of networks" of weather and climate observations.

Download or read book Shallow Clouds Water Vapor Circulation and Climate Sensitivity written by Robert Pincus and published by Springer. This book was released on 2019-02-01 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents a series of overview articles arising from a workshop exploring the links among shallow clouds, water vapor, circulation, and climate sensitivity. It provides a state-of-the art synthesis of understanding about the coupling of clouds and water vapor to the large-scale circulation. The emphasis is on two phenomena, namely the self-aggregation of deep convection and interactions between low clouds and the large-scale environment, with direct links to the sensitivity of climate to radiative perturbations. Each subject is approached using simulations, observations, and synthesizing theory; particular attention is paid to opportunities offered by new remote-sensing technologies, some still prospective. The collection provides a thorough grounding in topics representing one of the World Climate Research Program’s Grand Challenges. Previously published in Surveys in Geophysics, Volume 38, Issue 6, 2017 The aritcles “Observing Convective Aggregation”, “An Observational View of Relationships Between Moisture Aggregation, Cloud, and Radiative Heating Profiles”, “Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations”, “A Survey of Precipitation-Induced Atmospheric Cold Pools over Oceans and Their Interactions with the Larger-Scale Environment”, “Low-Cloud Feedbacks from Cloud-Controlling Factors: A Review”, “Mechanisms and Model Diversity of Trade-Wind Shallow Cumulus Cloud Feedbacks: A Review”, “Structure and Dynamical Influence of Water Vapor in the Lower Tropical Troposphere”, “Emerging Technologies and Synergies for Airborne and Space-Based Measurements of Water Vapor Profiles”, “Observational Constraints on Cloud Feedbacks: The Role of Active Satellite Sensors”, and “EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation” are available as open access articles under a CC BY 4.0 license at link.springer.com.

Download or read book An Evaluation of the Observational Capabilities of a Scanning 95 GHz Radar in Studying the 3D Structures of Marine Stratocumulus Clouds written by Kevin Bowley and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine stratocumulus clouds play a critical role in Earth's radiative balance primarily due to the role of their high albedo reflecting incoming solar radiation, causing a cooling effect, while weakly reflecting outgoing infrared radiation. Characterization of the 3-Dimensional (3D) structure of these cloud systems over scales of 20-40 km is required to accurately account for the role of cloud inhomogeneity and structure on their shortwave forcing and lifetime, which has important applications for Global Climate Models. For first time, such 3D measurements in clouds were made available from a scanning cloud radar during the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program's Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) field campaign in the Azores Islands. The scanning radar observations were complimented by a suite of zenith-pointing active and passive remote sensors that were deployed to provide a deta ...

Download or read book Global Physical Climatology written by Dennis L. Hartmann and published by Academic Press. This book was released on 1994-07-06 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global Physical Climatology is an introductory text devoted to the fundamental physical principles and problems of climate sensitivity and change. Addressing some of the most critical issues in climatology, this text features incisive coverage of topics that are central to understanding orbital parameter theory for past climate changes, and for anthropogenic and natural causes of near-future changes-- Key Features * Covers the physics of climate change * Examines the nature of the current climate and its previous changes * Explores the sensitivity of climate and the mechanisms by which humans are likely to produce near-future climate changes * Provides instructive end-of-chapter exercises and appendices

Download or read book Impacts of Turbulence on Cloud Microphysics and Warm rain Initiation written by Sisi Chen and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "In shallow cloud systems, such as cumulus or stratocumulus clouds, broad droplet size spectra and fast rain formation times are frequently observed using radar and in-situ measurements. However, these observations cannot be represented by classical condensational growth theory. Turbulence has been hypothesized to accelerate the formation of raindrops by enhancing the cloud droplet collision-coalescence process. In this thesis, the direct numerical simulation (DNS) approach is used to investigate the role of turbulence in cloud microphysics processes during warm-rain initiation and to quantify the effect of turbulence on the collision rate between droplets. We developed an accurate and sophisticated modeling framework that couples dynamics and thermodynamics, thus allowing the incorporation of droplet growth by simultaneous condensational and collisional processes under various turbulent conditions. Throughout the thesis, three sets of numerical experiments are conducted to study the turbulence impact on various droplet growth processes: 1) the droplet geometric collision, i.e., collisions without considering the disturbance flow induced by the presence of droplets, 2) the droplet hydrodynamic collisions, by including the disturbance flow, and 3) the interactions between condensational growth and collisional growth by further including the thermodynamic fields. The results of the first two sets of experiments demonstrate that for droplet pairs with different sizes (r1/r20.8), turbulence plays a dominant role in modifying the droplet hydrodynamic response to the local disturbance flow, weakly increasing the droplet relative velocity and creating the clustering of droplets in space. Consequentially, a significant enhancement of the collision efficiency and a mild enhancement of geometric collision kernel resulted. On the other hand, for droplet pairs with similar sizes (r1/r20.8), the turbulence enhancement in geometric collision and droplet hydrodynamic interactions is strong. Since droplet condensational growth produces a narrow droplet size distribution (DSD), we hypothesize that turbulence effectively widens the narrow spectrum by boosting similar-sized collisions. This hypothesis is further verified by conducting simulations of DSD evolution through collision-coalescence at various flow conditions. It is found that turbulence significantly broadens the DSD, and similar-sized collisions contribute to 21-24% of the total collisions compared to only 9% in the still-air experiments. Finally, we study the interaction of thermodynamics and dynamics and its impact on droplet growth by allowing droplets to simultaneously grow by condensation and collision in turbulent and non-turbulent environments. The results show that the condensational process promotes collisions in a turbulent environment while it reduces the collisions when in still air, indicating a positive impact of dynamics (turbulence) on the interaction of condensation and collision.In addition, we investigate the relative importance of different scales of turbulent flow on the collision statistics by varying the computational domain size. It is found that for small droplets (r

Download or read book Aviation Weather for Pilots and Flight Operations Personnel written by United States. Federal Aviation Administration and published by . This book was released on 1975 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Observational Study of the Processes of Entrainment and Detrainment of Cumulus Clouds Using in Situ and Airborne Cloud Radar Data written by Yonggang Wang and published by . This book was released on 2012 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation combines aircraft in situ and airborne mm-wave cloud radar measurements to make contributions to one fundamental aspect of the study of cumulus clouds: the effect of turbulent mixing. The objective is to improve the understanding of processes of entrainment and detrainment of cumulus clouds and their impacts on ambient air. The method used is compositing, i.e. the characterization of typical patterns, and their variations, by combining numerous samples, in this case samples of shallow to mediocre cumulus clouds. Clear evidence is produced to prove the existence of horizontal vortex-ring structures commonly observed within the top of cumulus clouds. Significant lateral and vertical entrainment of ambient air into clouds is described. The lateral entrainment occurs through relatively small eddies and the typical lateral mixing length is 10-15% of the cloud diameter, whereas vertical entrainment mainly occurs through a vortex-ring concentration within the upper half of cloud. In the developing stage of cumulus clouds, the cloud-scale vortex-ring circulation at cloud top has a more erosive effect on clouds than laterally-mixing eddies because the former penetrates deeper and thus reduces the buoyancy more effectively than the latter. The detrainment signature of a life cycle of non-precipitating moist convection is described as well. The layer containing orographic cumuli clearly becomes enriched with moist static energy immediately downwind of the cumuli. This enrichment reduces potential instability but increases ambient humidity, which may facilitate successive cumulus growth.

Download or read book Thriving on Our Changing Planet A Decadal Strategy for Earth Observation from Space written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2019-06-18 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: We live on a dynamic Earth shaped by both natural processes and the impacts of humans on their environment. It is in our collective interest to observe and understand our planet, and to predict future behavior to the extent possible, in order to effectively manage resources, successfully respond to threats from natural and human-induced environmental change, and capitalize on the opportunities â€" social, economic, security, and more â€" that such knowledge can bring. By continuously monitoring and exploring Earth, developing a deep understanding of its evolving behavior, and characterizing the processes that shape and reshape the environment in which we live, we not only advance knowledge and basic discovery about our planet, but we further develop the foundation upon which benefits to society are built. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space (National Academies Press, 2018) provides detailed guidance on how relevant federal agencies can ensure that the United States receives the maximum benefit from its investments in Earth observations from space, while operating within realistic cost constraints. This short booklet, designed to be accessible to the general public, provides a summary of the key ideas and recommendations from the full decadal survey report.

Download or read book Toward a Diurnal Climatology of Cold Season Turbulence Statistics in Continental Stratocumulus as Observed by the Atmospheric Radiation Millimeter Wavelength Cloud Radars written by and published by . This book was released on 2005 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerous observational studies of marine stratocumulus have demonstrated a pronounced diurnal cycle. At night, longwave flux divergence at the top of the cloud drives negatively buoyant eddies that tend to keep the boundary layer well mixed. During the day, solar absorption by the cloud tends to reduce the turbulent intensity and often decouples the planetary boundary layer (PBL) into cloud- and sub-cloud circulations. The delicate balance between turbulent intensity, entrainment, and fluxes dictates cloud geometry and persistence, which can significantly impact the shortwave radiation budget. Millimeter-wavelength cloud radars (MMCRs) have been used to study the turbulent structure of boundary layer stratocumulus (e.g. Frisch et al. 1995; Kollias and Albrecht 2000). Analysis is confined to nondrizzling or lightly drizzling cloud systems for which precipitation contamination is negligible. Under such assumptions the Doppler velocity field becomes a proxy for vertical velocity. Prior research has mainly consisted of a few case studies of specific cloud systems using radar scan strategies optimized for this particular cloud type. The MMCR operating at the Southern Great Plains Atmospheric Radiation Measurement Climate Research Facility is broadly configured to be able to detect many different cloud types over a broad range of reflectivities and altitudes, so it is not specifically optimized for PBL clouds. Being in more-or-less continuous operation since the end of 1996, it does, however, have the advantage of long data coverage, which suggests that statistically significant measures of the diurnal cycle of turbulence should be attainable. This abstract summarizes the first few steps toward this goal, using 7 months of cold season MMCR data.

Download or read book Airborne Measurements for Environmental Research written by Manfred Wendisch and published by John Wiley & Sons. This book was released on 2013-03-22 with total page 659 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first comprehensive review of airborne measurement principles covers all atmospheric components and surface parameters. It describes the common techniques to characterize aerosol particles and cloud/precipitation elements, while also explaining radiation quantities and pertinent hyperspectral and active remote sensing measurement techniques along the way. As a result, the major principles of operation are introduced and exemplified using specific instruments, treating both classic and emerging measurement techniques. The two editors head an international community of eminent scientists, all of them accepted and experienced specialists in their field, who help readers to understand specific problems related to airborne research, such as immanent uncertainties and limitations. They also provide guidance on the suitability of instruments to measure certain parameters and to select the correct type of device. While primarily intended for climate, geophysical and atmospheric researchers, its relevance to solar system objects makes this work equally appealing to astronomers studying atmospheres of solar system bodies with telescopes and space probes.

Download or read book The Atmosphere and Climate of Mars written by Robert M. Haberle and published by Cambridge University Press. This book was released on 2017-06-29 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Humanity has long been fascinated by the planet Mars. Was its climate ever conducive to life? What is the atmosphere like today and why did it change so dramatically over time? Eleven spacecraft have successfully flown to Mars since the Viking mission of the 1970s and early 1980s. These orbiters, landers and rovers have generated vast amounts of data that now span a Martian decade (roughly eighteen years). This new volume brings together the many new ideas about the atmosphere and climate system that have emerged, including the complex interplay of the volatile and dust cycles, the atmosphere-surface interactions that connect them over time, and the diversity of the planet's environment and its complex history. Including tutorials and explanations of complicated ideas, students, researchers and non-specialists alike are able to use this resource to gain a thorough and up-to-date understanding of this most Earth-like of planetary neighbours.

Download or read book An Introduction to Boundary Layer Meteorology written by Roland B. Stull and published by Springer Science & Business Media. This book was released on 1988-07-31 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part of the excitement in boundary-layer meteorology is the challenge associated with turbulent flow - one of the unsolved problems in classical physics. An additional attraction of the filed is the rich diversity of topics and research methods that are collected under the umbrella-term of boundary-layer meteorology. The flavor of the challenges and the excitement associated with the study of the atmospheric boundary layer are captured in this textbook. Fundamental concepts and mathematics are presented prior to their use, physical interpretations of the terms in equations are given, sample data are shown, examples are solved, and exercises are included. The work should also be considered as a major reference and as a review of the literature, since it includes tables of parameterizatlons, procedures, filed experiments, useful constants, and graphs of various phenomena under a variety of conditions. It is assumed that the work will be used at the beginning graduate level for students with an undergraduate background in meteorology, but the author envisions, and has catered for, a heterogeneity in the background and experience of his readers.

Download or read book Next Generation Earth System Prediction written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2016-08-22 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the nation's economic activities, security concerns, and stewardship of natural resources become increasingly complex and globally interrelated, they become ever more sensitive to adverse impacts from weather, climate, and other natural phenomena. For several decades, forecasts with lead times of a few days for weather and other environmental phenomena have yielded valuable information to improve decision-making across all sectors of society. Developing the capability to forecast environmental conditions and disruptive events several weeks and months in advance could dramatically increase the value and benefit of environmental predictions, saving lives, protecting property, increasing economic vitality, protecting the environment, and informing policy choices. Over the past decade, the ability to forecast weather and climate conditions on subseasonal to seasonal (S2S) timescales, i.e., two to fifty-two weeks in advance, has improved substantially. Although significant progress has been made, much work remains to make S2S predictions skillful enough, as well as optimally tailored and communicated, to enable widespread use. Next Generation Earth System Predictions presents a ten-year U.S. research agenda that increases the nation's S2S research and modeling capability, advances S2S forecasting, and aids in decision making at medium and extended lead times.