A Comparison Study of Precipitation Forecasts from Three Numerical Weather Prediction Systems PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download A Comparison Study of Precipitation Forecasts from Three Numerical Weather Prediction Systems PDF full book. Access full book title A Comparison Study of Precipitation Forecasts from Three Numerical Weather Prediction Systems by Madalina Surcel. Download full books in PDF and EPUB format.
Author: Madalina Surcel
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: Madalina Surcel
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: Robert S Plant
Publisher: World Scientific
ISBN: 1783266929
Category : Technology & Engineering
Languages : en
Pages : 1169
Get Book Here
Book Description
Precipitating atmospheric convection is fundamental to the Earth's weather and climate. It plays a leading role in the heat, moisture and momentum budgets. Appropriate modelling of convection is thus a prerequisite for reliable numerical weather prediction and climate modelling. The current standard approach is to represent it by subgrid-scale convection parameterization.Parameterization of Atmospheric Convection provides, for the first time, a comprehensive presentation of this important topic. The two-volume set equips readers with a firm grasp of the wide range of important issues, and thorough coverage is given of both the theoretical and practical aspects. This makes the parameterization problem accessible to a wider range of scientists than before. At the same time, by providing a solid bottom-up presentation of convection parameterization, this set is the definitive reference point for atmospheric scientists and modellers working on such problems.Volume 1 of this two-volume set focuses on the basic principles: introductions to atmospheric convection and tropical dynamics, explanations and discussions of key parameterization concepts, and a thorough and critical exploration of the mass-flux parameterization framework, which underlies the methods currently used in almost all operational models and at major climate modelling centres. Volume 2 focuses on the practice, which also leads to some more advanced fundamental issues. It includes: perspectives on operational implementations and model performance, tailored verification approaches, the role and representation of cloud microphysics, alternative parameterization approaches, stochasticity, criticality, and symmetry constraints.
Author: Mudasser Muneer Khan
Publisher:
ISBN:
Category : Numerical weather forecasting
Languages : en
Pages : 408
Get Book Here
Book Description
Precipitation forecasts play a key role in decision making for water resource planning and management. They also influence decisions taken for routine day-to-day operations by the users in various sectors including but not limited to agriculture, transportation, construction, hydropower generation, recreation and so forth. Streamflow forecasting is another major area of application where the quality of precipitation forecasts can greatly affect the overall performance of the system. The errors contained in the precipitation forecasts are introduced to the system at the very beginning. They may also lead to a final result that is far from the actual reality when propagated through different components of a streamflow forecasting system. Improving river flow forecasts for longer lead times by incorporating numerical weather predictions (NWP) into streamflow forecasting systems has attracted the attention of hydrologists in recent years. In order to account for the uncertainties in weather forecasting, meteorologists usually prefer to use an ensemble of NWP forecasts instead of relying on a single result. The process becomes considerably more complex and resource hungry when ensembles of NWP forecasts, known as ensemble prediction systems (EPS) are used to feed the flow forecasting models. In an operational setting, where the use of large weather ensembles may not be feasible due to the computational burden, identification of an objective methodology for optimal selection of smaller subsets becomes crucial. Forecasting of flash flooding demands a quick response and using multiple weather forecasts might not meet the requirements for timely decisions. Furthermore, more might not always result in better; inclusion or exclusion of some forecasts may affect the final forecast product. Hydrologists are therefore constrained to use a limited set of precipitation forecasts. There are very few studies in the literature addressing the issue of how ensemble size may affect the overall quality of the precipitation forecasts. Moreover, most of the previous research in this area is based on verification of ensemble systems against only the intense events. On the other hand, different users of weather forecasts have different needs and all are not always primarily interested in forecasts for the intense events. This study is the first to provide a comprehensive comparison of different ensemble prediction systems for their precipitation forecasts corresponding to users' needs in different sectors. The research also presents a unique evaluation of two combination methods for making a multi-model ensemble. This study leads also in comparing three statistical techniques to simplify ensembles. The research aims to provide users with an opportunity to select an ensemble of their choice, from the pool of current operational systems, keeping in view their specific needs and available resources. The target is achieved by presenting a size-based comparison of multiple ensemble systems in different decision scenarios. Three unimodel ensemble systems operational at the China Meteorological Agency (CMA), UK Met Office (UKMO) and the European Centre for Medium-Range Weather Forecasts (ECMWF) were tested for their precipitation forecasts to study the effect of ensemble size on its performance for a lead time as large as 10 days. Two multimodel ensembles constructed by using two distinct approaches for combining ensembles were also tested in this thesis. The study is based on precipitation forecasts from the above stated five ensemble systems and the precipitation and discharge data observed for the Waikato River in New Zealand. A comprehensive comparison of all the ensembles was made for four different applications of the precipitation forecasts. The deterministic and probabilistic performance of the ensemble forecasts were evaluated separately. Three different forecast attributes, accuracy, reliability and resolution, were evaluated for each ensemble. In attempting to find a suitable strategy for reducing the ensemble size, three statistical techniques were employed to obtain a reduced set of the precipitation ensembles. A river flow forecasting model based on gene expression programming (GEP) was subsequently forced by these reduced ensembles and the resulting ensemble forecasts for the river flow were evaluated against the corresponding observed flow. The results indicate that, in general, the size of an ensemble has small effect on its performance. The Control ensemble, consisting only of the control forecasts (generated using the best available estimate of the current state of the atmosphere) from the participating ensembles, was found to be as good in forecasting occurrence of rainfall as the Grand ensemble which consists of all 90 members of the three unimodel ensemble systems. Similarly, the ensemble forecasts for the most likely precipitation event, probability of exceeding a certain precipitation threshold and the magnitude of precipitation from the smaller ensembles were also comparable with the larger ensemble systems. No significant difference was observed between the flow forecasts driven by the smaller ensembles reduced by applying three stratification techniques and the corresponding full counterparts. In addition to the above findings, this research also presents the framework to evaluate different ensemble systems for their specific use. In this way, this PhD research attempts to develop a deeper understanding of the diverse applications of ensemble precipitation forecasts, as well as adding some case studies of a quantitative nature unlike most of the previous qualitative studies.
Author: Committee on the Assessment of the National Weather Service's Modernization Program
Publisher: National Academies Press
ISBN: 0309259738
Category : Science
Languages : en
Pages : 110
Get Book Here
Book Description
During the 1980s and 1990s, the National Weather Service (NWS) undertook a major program called the Modernization and Associated Restructuring (MAR). The MAR was officially completed in 2000. No comprehensive assessment of the execution of the MAR plan, or comparison of the promised benefits of the MAR to its actual impact, had ever been conducted. Therefore, Congress asked the National Academy of Sciences to conduct an end-to-end assessment. That report, The National Weather Service Modernization and Associated Restructuring: A Retrospective Assessment, concluded that the MAR was a success. Now, twelve years after the official completion of the MAR, the challenges faced by the NWS are no less important than those of the pre-MAR era. The three key challenges are: 1) Keeping Pace with accelerating scientific and technological advancement, 2) Meeting Expanding and Evolving User Needs in an increasingly information centric society, and 3) Partnering with an Increasingly Capable Enterprise that has grown considerably since the time of the MAR. Weather Services for the Nation presents three main recommendations for responding to these challenges. These recommendations will help the NWS address these challenges, making it more agile and effective. This will put it on a path to becoming second to none at integrating advances in science and technology into its operations and at meeting user needs, leading in some areas and keeping pace in others. It will have the highest quality core capabilities among national weather services. It will have a more agile organizational structure and workforce that allow it to directly or indirectly reach more end-users, save more lives, and help more businesses. And it will have leveraged these capabilities through the broader enterprise. This approach will make possible societal benefits beyond what the NWS budget alone allows.
Author: Madalina Surcel
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
"Despite the increased realism of convective-allowing Numerical Weather Prediction (NWP) forecasts, their accuracy has not improved as expected, especially for quantitative precipitation forecasting (QPF). Many factors can account for the poor QPF skill, from intrinsic predictability limitations to shortcomings of the evaluation method. Given the complexity of precipitation processes, more effort is needed to understand their predictability.In this thesis, data from NOAA's Hazardous Weather Testbed (HWT) forecasting Spring Experiments of 2008-2013 are analyzed to study precipitation predictability at the mesoscale. This unique data set, consisting of high-resolution (4-km grid spacing) ensemble precipitation forecasts covering most of the Continental US, with different types of perturbation methodologies and mesoscale data assimilation, allows the investigation of the QPF sensitivity to different forecast uncertainties.Several questions are addressed. First, a methodology is developed to quantify the loss of precipitation predictability with spatial scale and forecast time. Then, this methodology is applied to the 2008 data to characterize the scale dependence of the predictability of precipitation by an ensemble that has both large-scale initial and lateral boundary condition (IC/LBC) perturbations and varied model physics. The predictability by the ensemble is found to be very short-lived (2 hours for meso-[gamma] scales, and 10 hours for meso-[beta] scales). When compared to radar derived precipitation maps, the ensemble forecasts fully lose skill at meso-[beta] scales after the first 3 hours.The case-dependence of precipitation predictability is also explored. Statistical relationships between predictability and the effect of large-scale forcing are usually weak. However, two different types of precipitation systems can be identified: widespread systems associated with mid-latitude cyclones, and mesoscale systems whose evolution is modulated by the diurnal cycle of solar heating. While the overall predictability differs between these two types of cases, the rate at which predictability is lost with forecast time and spatial scale does not.By applying the methodology to the entire data set of 2008-2013, the impact of different types of ensemble perturbations can be assessed. The results show that all the types of perturbations analyzed here fail to generate sufficient dispersion, but that large-scale IC/LBC uncertainties account for most of the forecast error.The gain in QPF skill achieved through radar-data-assimilation, and the advantage of using these sophisticated NWP models rather than simpler statistical forecasting methods for very-short term forecasting are also discussed." --
Author: Lewis F. Richardson
Publisher:
ISBN:
Category : Numerical weather forecasting
Languages : en
Pages : 258
Get Book Here
Book Description
Author: Andrew Robertson
Publisher: Elsevier
ISBN: 012811715X
Category : Science
Languages : en
Pages : 588
Get Book Here
Book Description
The Gap Between Weather and Climate Forecasting: Sub-seasonal to Seasonal Prediction is an ideal reference for researchers and practitioners across the range of disciplines involved in the science, modeling, forecasting and application of this new frontier in sub-seasonal to seasonal (S2S) prediction. It provides an accessible, yet rigorous, introduction to the scientific principles and sources of predictability through the unique challenges of numerical simulation and forecasting with state-of-science modeling codes and supercomputers. Additional coverage includes the prospects for developing applications to trigger early action decisions to lessen weather catastrophes, minimize costly damage, and optimize operator decisions. The book consists of a set of contributed chapters solicited from experts and leaders in the fields of S2S predictability science, numerical modeling, operational forecasting, and developing application sectors. The introduction and conclusion, written by the co-editors, provides historical perspective, unique synthesis and prospects, and emerging opportunities in this exciting, complex and interdisciplinary field. Contains contributed chapters from leaders and experts in sub-seasonal to seasonal science, forecasting and applications Provides a one-stop shop for graduate students, academic and applied researchers, and practitioners in an emerging and interdisciplinary field Offers a synthesis of the state of S2S science through the use of concrete examples, enabling potential users of S2S forecasts to quickly grasp the potential for application in their own decision-making Includes a broad set of topics, illustrated with graphic examples, that highlight interdisciplinary linkages
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309180538
Category : Science
Languages : en
Pages : 124
Get Book Here
Book Description
Uncertainty is a fundamental characteristic of weather, seasonal climate, and hydrological prediction, and no forecast is complete without a description of its uncertainty. Effective communication of uncertainty helps people better understand the likelihood of a particular event and improves their ability to make decisions based on the forecast. Nonetheless, for decades, users of these forecasts have been conditioned to receive incomplete information about uncertainty. They have become used to single-valued (deterministic) forecasts (e.g., "the high temperature will be 70 degrees Farenheit 9 days from now") and applied their own experience in determining how much confidence to place in the forecast. Most forecast products from the public and private sectors, including those from the National Oceanographic and Atmospheric Administration's National Weather Service, continue this deterministic legacy. Fortunately, the National Weather Service and others in the prediction community have recognized the need to view uncertainty as a fundamental part of forecasts. By partnering with other segments of the community to understand user needs, generate relevant and rich informational products, and utilize effective communication vehicles, the National Weather Service can take a leading role in the transition to widespread, effective incorporation of uncertainty information into predictions. "Completing the Forecast" makes recommendations to the National Weather Service and the broader prediction community on how to make this transition.
Author:
Publisher:
ISBN:
Category : Meteorology
Languages : en
Pages : 1164
Get Book Here
Book Description
Author: Robert Sharman
Publisher: Springer
ISBN: 331923630X
Category : Technology & Engineering
Languages : en
Pages : 529
Get Book Here
Book Description
Anyone who has experienced turbulence in flight knows that it is usually not pleasant, and may wonder why this is so difficult to avoid. The book includes papers by various aviation turbulence researchers and provides background into the nature and causes of atmospheric turbulence that affect aircraft motion, and contains surveys of the latest techniques for remote and in situ sensing and forecasting of the turbulence phenomenon. It provides updates on the state-of-the-art research since earlier studies in the 1960s on clear-air turbulence, explains recent new understanding into turbulence generation by thunderstorms, and summarizes future challenges in turbulence prediction and avoidance.
