Download or read book Sensitivity of Convective Precipitation Forecasts to Soil Moisture and Vegetation written by Thomas William Collow and published by . This book was released on 2014 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Land surface properties play a major role in convective precipitation events through impacting the amount of surface evaporation which results in changes to near surface temperature and humidity. This study examines the effects of using soil moisture data from the North American Regional Reanalysis (NARR) and the Soil Moisture Ocean Salinity Satellite (SMOS) on short term weather forecasts using the Weather Research and Forecasting Model (WRF). SMOS soil moisture data were compared to in-situ observations and it was found that although they captured the spatial variation in soil moisture, the actual measurements had a dry bias of roughly 0.10 m3/m3. Large differences existed between the in-situ observations, even for probes only a few meters apart. Observations from different sensors within a SMOS footprint differed from each other by a larger amount than they differed from the SMOS retrieval. Removing the mean and normalizing the data brought the in-situ observations into better agreement with each other and with SMOS but they still contained substantial differences. WRF sensitivity experiments demonstrated that changes to initial values of soil moisture resulted in no significant changes in precipitation. However, more of an impact was seen when the vegetation was changed, with barren vegetation yielding a substantial decrease in precipitation. Adding soil moisture resulted in significant changes to 2 m temperature and dewpoint relative to the control runs for each vegetation type. However, it was found that convective available potential energy and moist static energy change little, as the temperature and humidity impacts on these variables cancel each other out, which explain the limited precipitation response. SMOS data resulted in no significant changes in precipitation forecasts but had some impacts on temperature and humidity forecasts. However, because these results were not seen in all cases, no definitive conclusions about the usefulness of SMOS for high resolution numerical modeling can be made at this time. These results provide major implications for future satellite missions such as Soil Moisture Active Passive showing that experiments using true data assimilation methods which give only partial weight to satellite data may also not provide significant improvements to weather forecasts.
Download or read book The Representation of Cumulus Convection in Numerical Models written by Kerry Emanuel and published by Springer. This book was released on 2015-03-30 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents descriptions of numerical models for testing cumulus in cloud fields. It is divided into six parts. Part I provides an overview of the problem, including descriptions of cumulus clouds and the effects of ensembles of cumulus clouds on mass, momentum, and vorticity distributions. A review of closure assumptions is also provided. A review of "classical" convection schemes in widespread use is provided in Part II. The special problems associated with the representation of convection in mesoscale models are discussed in Part III, along with descriptions of some of the commonly used mesoscale schemes. Part IV covers some of the problems associated with the representation of convection in climate models, while the parameterization of slantwise convection is the subject of Part V.
Download or read book Sensitivity of Summertime Weather Forecasts to Differences in Soil Moisture and the Implication for Ensemble Weather Forecasting written by Christian Johann Sutton and published by . This book was released on 2005 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Improvement in Convective Precipitation and Land Surface Prediction Over Complex Terrain written by Tiantian Xiang and published by . This book was released on 2016 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Land surface fluxes of energy and mass developed over heterogeneous mountain landscapes are fundamental to atmospheric processes. However, due to their high complexity and the lack of spatial observations, land surface processes and land-atmosphere interactions are not fully understood in mountain regions. This thesis investigates land surface processes and their impact on convective precipitation by conducting numerical modeling experiments at multiple scales over the North American Monsoon (NAM) region. Specifically, the following scientific questions are addressed: (1) how do land surface conditions evolve during the monsoon season, and what are their main controls?, (2) how do the diurnal cycles of surface energy fluxes vary during the monsoon season for the major ecosystems?, and (3) what are the impacts of surface soil moisture and vegetation condition on convective precipitation? Hydrologic simulation using the TIN-based Real-time Integrated Basin Simulator (tRIBS) is firstly carried out to examine the seasonal evolution of land surface conditions. Results reveal that the spatial heterogeneity of land surface temperature and soil moisture increases dramatically with the onset of monsoon, which is related to seasonal changes in topographic and vegetation controls. Similar results are found at regional basin scale using the uncoupled WRF-Hydro model. Meanwhile, the diurnal cycles of surface energy fluxes show large variation between the major ecosystems. Differences in both the peak magnitude and peak timing of plant transpiration induce mesoscale heterogeneity in land surface conditions. Lastly, this dissertation examines the upscale effect of land surface heterogeneity on atmospheric condition through fully-coupled WRF-Hydro simulations. A series of process-based experiments were conducted to identify the pathways of soil moisture-rainfall feedback mechanism over the NAM region. While modeling experiments confirm the existence of positive soil moisture/vegetation-rainfall feedback, their exact pathways are slightly different. Interactions between soil moisture, vegetation cover, and rainfall through a series of land surface and atmospheric boundary layer processes highlight the strong land-atmosphere coupling in the NAM region, and have important implications on convective rainfall prediction. Overall, this dissertation advances the study of complex land surface processes over the NAM region, and made important contributions in linking complex hydrologic, ecologic and atmospheric processes through numerical modeling.
Download or read book Clouds and Climate written by A. Pier Siebesma and published by Cambridge University Press. This book was released on 2020-08-20 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive overview of research on clouds and their role in our present and future climate, for advanced students and researchers.
Download or read book Assessment of Intraseasonal to Interannual Climate Prediction and Predictability written by National Research Council and published by National Academies Press. This book was released on 2010-10-08 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: More accurate forecasts of climate conditions over time periods of weeks to a few years could help people plan agricultural activities, mitigate drought, and manage energy resources, amongst other activities; however, current forecast systems have limited ability on these time- scales. Models for such climate forecasts must take into account complex interactions among the ocean, atmosphere, and land surface. Such processes can be difficult to represent realistically. To improve the quality of forecasts, this book makes recommendations about the development of the tools used in forecasting and about specific research goals for improving understanding of sources of predictability. To improve the accessibility of these forecasts to decision-makers and researchers, this book also suggests best practices to improve how forecasts are made and disseminated.
Download or read book Uncertainties in Numerical Weather Prediction written by Haraldur Olafsson and published by Elsevier. This book was released on 2020-11-25 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: Uncertainties in Numerical Weather Prediction is a comprehensive work on the most current understandings of uncertainties and predictability in numerical simulations of the atmosphere. It provides general knowledge on all aspects of uncertainties in the weather prediction models in a single, easy to use reference. The book illustrates particular uncertainties in observations and data assimilation, as well as the errors associated with numerical integration methods. Stochastic methods in parameterization of subgrid processes are also assessed, as are uncertainties associated with surface-atmosphere exchange, orographic flows and processes in the atmospheric boundary layer. Through a better understanding of the uncertainties to watch for, readers will be able to produce more precise and accurate forecasts. This is an essential work for anyone who wants to improve the accuracy of weather and climate forecasting and interested parties developing tools to enhance the quality of such forecasts. - Provides a comprehensive overview of the state of numerical weather prediction at spatial scales, from hundreds of meters, to thousands of kilometers - Focuses on short-term 1-15 day atmospheric predictions, with some coverage appropriate for longer-term forecasts - Includes references to climate prediction models to allow applications of these techniques for climate simulations
Download or read book Handbook of Hydrometeorological Ensemble Forecasting written by Qingyun Duan and published by Springer. This book was released on 2016-05-06 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrometeorological prediction involves the forecasting of the state and variation of hydrometeorological elements -- including precipitation, temperature, humidity, soil moisture, river discharge, groundwater, etc.-- at different space and time scales. Such forecasts form an important scientific basis for informing public of natural hazards such as cyclones, heat waves, frosts, droughts and floods. Traditionally, and at most currently operational centers, hydrometeorological forecasts are deterministic, “single-valued” outlooks: i.e., the weather and hydrological models provide a single best guess of the magnitude and timing of the impending events. These forecasts suffer the obvious drawback of lacking uncertainty information that would help decision-makers assess the risks of forecast use. Recently, hydrometeorological ensemble forecast approaches have begun to be developed and used by operational collection of hydrometeorological services. In contrast to deterministic forecasts, ensemble forecasts are a multiple forecasts of the same events. The ensemble forecasts are generated by perturbing uncertain factors such as model forcings, initial conditions, and/or model physics. Ensemble techniques are attractive because they not only offer an estimate of the most probable future state of the hydrometeorological system, but also quantify the predictive uncertainty of a catastrophic hydrometeorological event occurring. The Hydrological Ensemble Prediction Experiment (HEPEX), initiated in 2004, has signaled a new era of collaboration toward the development of hydrometeorological ensemble forecasts. By bringing meteorologists, hydrologists and hydrometeorological forecast users together, HEPEX aims to improve operational hydrometeorological forecast approaches to a standard that can be used with confidence by emergencies and water resources managers. HEPEX advocates a hydrometeorological ensemble prediction system (HEPS) framework that consists of several basic building blocks. These components include:(a) an approach (typically statistical) for addressing uncertainty in meteorological inputs and generating statistically consistent space/time meteorological inputs for hydrological applications; (b) a land data assimilation approach for leveraging observation to reduce uncertainties in the initial and boundary conditions of the hydrological system; (c) approaches that address uncertainty in model parameters (also called ‘calibration’); (d) a hydrologic model or other approach for converting meteorological inputs into hydrological outputs; and finally (e) approaches for characterizing hydrological model output uncertainty. Also integral to HEPS is a verification system that can be used to evaluate the performance of all of its components. HEPS frameworks are being increasingly adopted by operational hydrometeorological agencies around the world to support risk management related to flash flooding, river and coastal flooding, drought, and water management. Real benefits of ensemble forecasts have been demonstrated in water emergence management decision making, optimization of reservoir operation, and other applications.
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.
Download or read book Applications of Soil Physics written by Daniel Hillel and published by Elsevier. This book was released on 2012-12-02 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Applications of Soil Physics deals with the applications of soil physics and covers topics ranging from infiltration and surface runoff to groundwater drainage, evaporation from bare-surface soils, and uptake of soil moisture by plants. Water balance and energy balance in the field are also discussed, along with tillage and soil structure management. The development and extension of Penman's evaporation formula is also described. This book is comprised of 14 chapters and begins with a systematic description of the field-water cycle and its management, with emphasis on infiltration and runoff; redistribution and drainage; evaporation and transpiration; and irrigation and tillage. Subsequent chapters focus on transpiration from plant canopies; freezing phenomena in soils; scaling and similitude of soil-water phenomena; spatial variability of soil physical properties; and movement of solutes during infiltration into homogeneous soil. Concepts of soil-water availability to plants are considered, together with principles of irrigation management and the advantages and limitations of drip irrigation. This monograph is intended for upper-level undergraduate and graduate students of the environmental, engineering, and agronomic sciences.
Download or read book Changing Precipitation Regimes and Terrestrial Ecosystems written by Jake F. Weltzin and published by University of Arizona Press. This book was released on 2003-01-01 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: By the beginning of the twenty-first century, few people could deny the reality of global change. But while most alarm has been over increasing temperatures, other changes are occurring in precipitation patternsÑvariations that may be due in part to global warming but also to factors such as changes in atmospheric circulation and land surfaces. This volume provides a central source of information about this newly emerging area of global change research. It presents ongoing investigations into the responses of plant communities and ecosystems to the experimental manipulation of precipitation in a variety of field settingsÑparticularly in the western and central United States, where precipitation is already scarce or variable. By exploring methods that can be used to predict responses of ecosystems to changes in precipitation regimes, it demonstrates new approaches to global change research and highlights the importance of precipitation regimes in structuring ecosystems. The contributors first document the importance of precipitation, soil characteristics, and soil moisture to plant life. They then focus on the roles of precipitation amount, seasonality, and frequency in shaping varied terrestrial ecosystems: desert, sagebrush steppe, oak savanna, tall- and mixed-grass prairie, and eastern deciduous forest. These case studies illustrate many complex, tightly woven, interactive relationships among precipitation, soils, and plantsÑrelationships that will dictate the responses of ecosystems to changes in precipitation regimes. The approaches utilized in these chapters include spatial comparisons of vegetation structure and function across different ecosytems; analyses of changes in plant architecture and physiology in response to temporal variation in precipitation; experiments to manipulate water availability; and modeling approaches that characterize the relationships between climate variables and vegetation types. All seek to assess vegetation responses to major shifts in climate that appear to be occurring at present and may become the norm in the future. As the first volume to discuss and document current and cutting-edge concepts and approaches to research into changing precipitation regimes and terrestrial ecosystems, this book shows the importance of developing reliable predictions of the precipitation changes that may occur with global warming. These studies clearly demonstrate that patterns of environmental variation and the nature of vegetation responses are complex phenomena that are only beginning to be understood, and that these experimental approaches are critical for our understanding of future change.
Download or read book Measuring Precipitation from Space written by V. Levizzani and published by Springer Science & Business Media. This book was released on 2007-05-11 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt: No other book can offer such a powerful tool to understand the basics of remote sensing for precipitation, to make use of existing products and to have a glimpse of the near future missions and instruments. This book features state-of-the-art rainfall estimation algorithms, validation strategies, and precipitation modeling. More than 20 years after the last book on the subject the worldwide precipitation community has produced a comprehensive overview of its activities, achievements, ongoing research and future plans.
Download or read book Hydrological Drought written by Lena M. Tallaksen and published by Gulf Professional Publishing. This book was released on 2004 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: The majority of the examples are taken from regions where the rivers run most of the year.
Download or read book Monthly Weather Review written by and published by . This book was released on 2007 with total page 1652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Decade to Century Scale Climate Variability and Change written by National Research Council and published by National Academies Press. This book was released on 1998-12-24 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Society today may be more vulnerable to global-scale, long-term, climate change than ever before. Even without any human influence, past records show that climate can be expected to continue to undergo considerable change over decades to centuries. Measures for adaption and mitigation will call for policy decisions based on a sound scientific foundation. Better understanding and prediction of climate variations can be achieved most efficiently through a nationally recognized "dec-cen" science plan. This book articulates the scientific issues that must be addressed to advance us efficiently toward that understanding and outlines the data collection and modeling needed.
Download or read book The Heat Balance of the Earth s Surface written by Mikhail Ivanovich Budyko and published by . This book was released on 1958 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Urban Climates written by T. R. Oke and published by Cambridge University Press. This book was released on 2017-09-14 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: Urban Climates is the first full synthesis of modern scientific and applied research on urban climates. The book begins with an outline of what constitutes an urban ecosystem. It develops a comprehensive terminology for the subject using scale and surface classification as key constructs. It explains the physical principles governing the creation of distinct urban climates, such as airflow around buildings, the heat island, precipitation modification and air pollution, and it then illustrates how this knowledge can be applied to moderate the undesirable consequences of urban development and help create more sustainable and resilient cities. With urban climate science now a fully-fledged field, this timely book fulfills the need to bring together the disparate parts of climate research on cities into a coherent framework. It is an ideal resource for students and researchers in fields such as climatology, urban hydrology, air quality, environmental engineering and urban design.
