Assessing Impacts of PBL and Surface Layer Schemes in Simulating the Surface-atmosphere Interactions and Precipitation Over the Tropical Ocean Using Observations from AMIE/DYNAMO. PDF Download
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Category :
Languages : en
Pages : 20
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Book Description
Accuracy of turbulence parameterization in representing Planetary Boundary Layer (PBL) processes in climate models is critical for predicting the initiation and development of clouds, air quality issues, and underlying surface-atmosphere-cloud interactions. In this study, we 1) evaluate WRF model-simulated spatial patterns of precipitation and surface fluxes, as well as vertical profiles of potential temperature, humidity, moist static energy and moisture tendency terms as simulated by WRF at various spatial resolutions and with PBL, surface layer and shallow convection schemes against measurements, 2) identify model biases by examining the moisture tendency terms contributed by PBL and convection processes through nudging experiments, and 3) evaluate the dependence of modeled surface latent heat (LH) fluxes onPBL and surface layer schemes over the tropical ocean. The results show that PBL and surface parameterizations have surprisingly large impacts on precipitation, convection initiation and surface moisture fluxes over tropical oceans. All of the parameterizations tested tend to overpredict moisture in PBL and free atmosphere, and consequently result in larger moist static energy and precipitation. Moisture nudging tends to suppress the initiation of convection and reduces the excess precipitation. The reduction in precipitation bias in turn reduces the surface wind and LH flux biases, which suggests that the model drifts at least partly because of a positive feedback between precipitation and surface fluxes. The updated shallow convection scheme KF-CuP tends to suppress the initiation and development of deep convection, consequently decreasing precipitation. The Eta surface layer scheme predicts more reasonable LH fluxes and the LH-Wind Speed relationship than the MM5 scheme, especially when coupled with the MYJ scheme. By examining various parameterization schemes in WRF, we identify sources of biases and weaknesses of current PBL, surface layer and shallow convection schemes in reproducing PBL processes, the initiation of convection and intra-seasonal variability of precipitation.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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Book Description
Accuracy of turbulence parameterization in representing Planetary Boundary Layer (PBL) processes in climate models is critical for predicting the initiation and development of clouds, air quality issues, and underlying surface-atmosphere-cloud interactions. In this study, we 1) evaluate WRF model-simulated spatial patterns of precipitation and surface fluxes, as well as vertical profiles of potential temperature, humidity, moist static energy and moisture tendency terms as simulated by WRF at various spatial resolutions and with PBL, surface layer and shallow convection schemes against measurements, 2) identify model biases by examining the moisture tendency terms contributed by PBL and convection processes through nudging experiments, and 3) evaluate the dependence of modeled surface latent heat (LH) fluxes onPBL and surface layer schemes over the tropical ocean. The results show that PBL and surface parameterizations have surprisingly large impacts on precipitation, convection initiation and surface moisture fluxes over tropical oceans. All of the parameterizations tested tend to overpredict moisture in PBL and free atmosphere, and consequently result in larger moist static energy and precipitation. Moisture nudging tends to suppress the initiation of convection and reduces the excess precipitation. The reduction in precipitation bias in turn reduces the surface wind and LH flux biases, which suggests that the model drifts at least partly because of a positive feedback between precipitation and surface fluxes. The updated shallow convection scheme KF-CuP tends to suppress the initiation and development of deep convection, consequently decreasing precipitation. The Eta surface layer scheme predicts more reasonable LH fluxes and the LH-Wind Speed relationship than the MM5 scheme, especially when coupled with the MYJ scheme. By examining various parameterization schemes in WRF, we identify sources of biases and weaknesses of current PBL, surface layer and shallow convection schemes in reproducing PBL processes, the initiation of convection and intra-seasonal variability of precipitation.
Author: David A. Randall
Publisher: Springer
ISBN: 9811333963
Category : Science
Languages : en
Pages : 377
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Book Description
This book focuses on the development of physical parameterization over the last 2 to 3 decades and provides a roadmap for its future development. It covers important physical processes: convection, clouds, radiation, land-surface, and the orographic effect. The improvement of numerical models for predicting weather and climate at a variety of places and times has progressed globally. However, there are still several challenging areas, which need to be addressed with a better understanding of physical processes based on observations, and to subsequently be taken into account by means of improved parameterization. And this is all the more important since models are increasingly being used at higher horizontal and vertical resolutions. Encouraging debate on the cloud-resolving approach or the hybrid approach with parameterized convection and grid-scale cloud microphysics and its impact on models’ intrinsic predictability, the book offers a motivating reference guide for all researchers whose work involves physical parameterization problems and numerical models.
Author: J. R. Garratt
Publisher: Cambridge University Press
ISBN: 9780521467452
Category : Mathematics
Languages : en
Pages : 340
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Book Description
The book gives a comprehensive and lucid account of the science of the atmospheric boundary layer (ABL). There is an emphasis on the application of the ABL to numerical modelling of the climate. The book comprises nine chapters, several appendices (data tables, information sources, physical constants) and an extensive reference list. Chapter 1 serves as an introduction, with chapters 2 and 3 dealing with the development of mean and turbulence equations, and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modelling of the ABL is crucially dependent for its realism on the surface boundary conditions, and chapters 4 and 5 deal with aerodynamic and energy considerations, with attention to both dry and wet land surfaces and sea. The structure of the clear-sky, thermally stratified ABL is treated in chapter 6, including the convective and stable cases over homogeneous land, the marine ABL and the internal boundary layer at the coastline. Chapter 7 then extends the discussion to the cloudy ABL. This is seen as particularly relevant, since the extensive stratocumulus regions over the subtropical oceans and stratus regions over the Arctic are now identified as key players in the climate system. Finally, chapters 8 and 9 bring much of the book's material together in a discussion of appropriate ABL and surface parameterization schemes in general circulation models of the atmosphere that are being used for climate simulation.
Author: RB Singh
Publisher: Springer
ISBN: 3319289772
Category : Science
Languages : en
Pages : 404
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Book Description
This book provides information essential for anyone interested in climate and environmental change of the Himalayan region, including land and resource managers, environmental planners, conservationists, environmentalists, geographers, climatologists, ecologists, and students. The book is unique in its coverage of the current understanding of the science of climate change in the Himalayan mountain system and of the major impacts on physical systems and ecosystems. The book gives an overview of the physical science basis of climate change and explains drivers and processes of glacier and vegetation dynamics. The book covers relevant aspects of accelerated climate change observed in the Himalayan mountain system, and highlights the regional differentiation of climatic changes and associated environmental modifications. The focus is on climate variability and change, and how physical systems and ecosystems respond to climate change impacts. Consequences include impacts on physical systems such as glacier shrinkage, glacial lake outburst floods, altered hydrological characteristics, permafrost warming and thawing, and mass movements on slopes. Climate change is also a powerful stressor on ecosystems and induces range shifts of plant and animal species and alterations in terms of phenology, biomass, plant cover, plant group dominance and species composition. Thus, ecosystem structure and functioning will be strongly affected. The book has an introductory chapter followed by a section on climate change, a section on impacts on glaciers and hydrology, and a section on vegetation dynamics. Each section has several chapters presenting key concepts, major drivers and key processes of environmental change in the Himalayan region from different perspectives. Climate change impacts in the Himalaya have not been studied in much detail, and respective findings were not presented so far in a comprehensive overview. This book summarizes the current knowledge of interactions between climate change and the dynamics of glaciers, hydrology, and vegetation.
Author: David J. Stensrud
Publisher: Cambridge University Press
ISBN: 0521865409
Category : Science
Languages : en
Pages : 408
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Book Description
Contents: 1.
Author: S. Pal Arya
Publisher: Academic Press
ISBN: 0120593548
Category : Nature
Languages : en
Pages : 448
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Book Description
James R. Holton
Author: J. C. Kaimal
Publisher: Oxford University Press, USA
ISBN: 0195062396
Category : Nature
Languages : en
Pages : 304
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Book Description
This text gives a simple view of the structure of the boundary layer, the instruments available for measuring its mean and turbulent properties, how best to make the measurements, and ways to process and analyze the data.
Author: Robert A. Houze Jr.
Publisher: Elsevier
ISBN: 0080502105
Category : Science
Languages : en
Pages : 605
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Book Description
Clouds play a critical role in the Earth's climate, general atmospheric circulation, and global water balance. Clouds are essential elements in mesoscale meteorology, atmospheric chemistry, air pollution, atmosphericradiation, and weather forecasting, and thus must be understood by any student or researcher in the atmospheric sciences.Cloud Dynamics provides a skillful and comprehensive examination of the nature of clouds--what they look like and why, how scientists observe them, and the basic dynamics and physics that underlie them. The book describes the mechanics governing each type of cloud that occurs in Earth's atmosphere, and the organization of various types of clouds in larger weather systems such as fronts, thunderstorms, and hurricanes.This book is aimed specifically at graduate students, advanced undergraduates, practicing researchers either already in atmospheric science or moving in from a related scientific field, and operational meteorologists. Some prior knowledge of atmospheric dynamics and physics is helpful, but a thorough overview of the necessary prerequisites is supplied. - Provides a complete treatment of clouds integrating the analysis of air motions with cloud structure, microphysics, and precipitation mechanics - Describes and explains the basic types of clouds and cloud systems that occur in the atmosphere-fog, stratus, stratocumulus, altocumulus, altostratus, cirrus, thunderstorms, tornadoes, waterspouts, orographically induced clouds, mesoscale convection complexes, hurricanes, fronts, and extratropical cyclones - Presents a photographic guide, presented in the first chapter, linking the examination of each type of cloud with an image to enhance visual retention and understanding - Summarizes the fundamentals, both observational and theoretical, of atmospheric dynamics, thermodynamics, cloud microphysics, and radar meteorology, allowing each type of cloud to be examined in depth - Integrates the latest field observations, numerical model simulations, and theory - Supplies a theoretical treatment suitable for the advanced undergraduate or graduate level
Author: Shunlin Liang
Publisher: Springer Science & Business Media
ISBN: 3319025880
Category : Technology & Engineering
Languages : en
Pages : 171
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Book Description
This book describes the algorithms, validation and preliminary analysis of the Global LAnd Surface Satellite (GLASS) products, a long-term, high-quality dataset that is now freely available worldwide to government organizations and agencies, scientific research institutions, students and members of the general public. The GLASS products include leaf area index, broadband albedo, broadband emissivity, downward shortwave radiation and photosynthetically active radiation. The first three GLASS products cover 1981 to 2012 with 1km and 5km spatial resolutions and 8-day temporal resolution, and the last two GLASS products span 2008 to 2010 with 3-hour temporal resolution and 5km spatial resolution. These GLASS products are unique. The first three are spatially continuous and cover the longest period of time among all current similar satellite products. The other two products are the highest spatial-resolution global radiation products from satellite observations that are currently available. These products can be downloaded from Beijing Normal University at http://glass-product.bnu.edu.cn/ and the University of Maryland Global Land Cover Facility at http://www.glcf.umd.edu/ The GLASS products are the outcome of a key research project entitled “Generation & Applications of Global Products of Essential Land Variables”, supported by funding from the High-Tech Research and Development Program of China and involving dozens of institutions and nearly one hundred scientists and researchers. Following an introduction, the book contains five chapters corresponding to these five GLASS products: background, algorithm, quality control and validation, preliminary analysis and applications. It discusses the long-term environmental changes detected from the GLASS products and other data sources at both global and local scales and also provides detailed analysis of regional hotspots where environmental changes are mainly associated with climate change, drought, land-atmosphere interactions, and human activities. The book is based primarily on a set of published journal papers about these five GLASS products and includes updated information. Since these products have now begun to be widely used, this book is an essential reference document. It is also a very helpful resource to anyone interested in satellite remote sensing and its applications.
Author: Stéphane Vannitsem
Publisher: Elsevier
ISBN: 012812248X
Category : Science
Languages : en
Pages : 364
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Book Description
Statistical Postprocessing of Ensemble Forecasts brings together chapters contributed by international subject-matter experts describing the current state of the art in the statistical postprocessing of ensemble forecasts. The book illustrates the use of these methods in several important applications including weather, hydrological and climate forecasts, and renewable energy forecasting. After an introductory section on ensemble forecasts and prediction systems, the second section of the book is devoted to exposition of the methods available for statistical postprocessing of ensemble forecasts: univariate and multivariate ensemble postprocessing are first reviewed by Wilks (Chapters 3), then Schefzik and Möller (Chapter 4), and the more specialized perspective necessary for postprocessing forecasts for extremes is presented by Friederichs, Wahl, and Buschow (Chapter 5). The second section concludes with a discussion of forecast verification methods devised specifically for evaluation of ensemble forecasts (Chapter 6 by Thorarinsdottir and Schuhen). The third section of this book is devoted to applications of ensemble postprocessing. Practical aspects of ensemble postprocessing are first detailed in Chapter 7 (Hamill), including an extended and illustrative case study. Chapters 8 (Hemri), 9 (Pinson and Messner), and 10 (Van Schaeybroeck and Vannitsem) discuss ensemble postprocessing specifically for hydrological applications, postprocessing in support of renewable energy applications, and postprocessing of long-range forecasts from months to decades. Finally, Chapter 11 (Messner) provides a guide to the ensemble-postprocessing software available in the R programming language, which should greatly help readers implement many of the ideas presented in this book. Edited by three experts with strong and complementary expertise in statistical postprocessing of ensemble forecasts, this book assesses the new and rapidly developing field of ensemble forecast postprocessing as an extension of the use of statistical corrections to traditional deterministic forecasts. Statistical Postprocessing of Ensemble Forecasts is an essential resource for researchers, operational practitioners, and students in weather, seasonal, and climate forecasting, as well as users of such forecasts in fields involving renewable energy, conventional energy, hydrology, environmental engineering, and agriculture. - Consolidates, for the first time, the methodologies and applications of ensemble forecasts in one succinct place - Provides real-world examples of methods used to formulate forecasts - Presents the tools needed to make the best use of multiple model forecasts in a timely and efficient manner
