Research and technology

Activities of the Goddard Space Flight Center are described in the areas of planets and interplanetary media, comets, astronomy and high-energy physics, solar physics, atmospheres, terrestrial physics, ocean science, sensors and space technology, techniques, user space data systems, space communications and navigation, and system and software engineering. Flight projects and mission definition studies are presented, and institutional technology is described

Assessment of the impact of climate change on hydroelectric power

Global climate change is one of the greatest challenges of the twenty-first century. Rising temperatures and alteration of weather patterns are anticipated to result from increased atmospheric concentrations of greenhouse gases, caused, in part, by the use of fossil fuels for electricity generation. Climate change is predicted to have major impacts on many aspects of human society from agriculture to water supply. The process of limiting the extent of climatic change began with the Kyoto Protocol, committing industrialised nations to modest cuts in their emissions. To achieve these and in the longer term, much greater cuts, electricity production must reduce its reliance on fossil fuels, by the increased use of renewable resources. Hydropower is currently the only major renewable source contributing to energy supply, and its future contribution is anticipated to increase significantly. However, the successful expansion of hydropower is dependent on the availability of the resource and the perceptions of those financing it. Increased evaporation, as a result of higher temperatures, together with changes in precipitation patterns may alter the timing and magnitude of river flows. This will affect the ability of hydropower stations to harness the resource, and may result in reduced energy production, implying lower revenues and poorer financial returns. The continuing liberalisation of the electricity industry implies that, increasingly, profitability and the level of risk will drive investment decision-making. As such, investors will be concerned with processes, such as climatic change, that have the potential to alter the balance of risk and reward. This thesis describes a methodology to assess the potential impact of climatic change on hydropower investment, and details the implementation of a technique for quantifying changes in profitability and risk. A case study is presented as an illustration, the results of which are analysed with respect to the implications for future provision of hydropower, as well as our ability to limit the extent of climatic change

Literature review of the remote sensing of natural resources

A bibliography is presented concerning remote sensing techniques. Abstracts of recent periodicals are included along with author, and keyword indexes

Development and assessment of dynamic storage cell codes for flood inundation modelling

Since 1962 storage cell codes have been developed to simulate flow on fluvial and coastal floodplains. These models treat the floodplain as a series of discrete storage cells, with the flow between cells calculated explicitly using some analytical flow formulae such as the Manning equation. Recently these codes have been reconfigured to use regular Cartesian grids to make full use of widely available high resolution data captured from remote sensing platforms and stored in a raster GIS format. Such raster-based storage cell codes have many of the advantages over full two-dimensional depth averaged schemes but without the computational cost, however their typical implementation results in a number of fundamental limitations. These include an inability to develop solutions that are independent of time step or grid size, and an unrealistic lack of sensitivity to floodplain friction. In this thesis, a new solution to these problems is proposed based on an optimal adaptive time step determined using a Courant-type condition for model stability. Comparison of this new adaptive time step scheme to analytical solutions of wave propagation/recession on flat and sloping planar surfaces and against field measurements acquired for four real flood scenarios demonstrates considerable improvement over a standard raster storage cell model. Moreover, the new scheme is shown to yield results that are independent of grid size or choice of initial time step and which show an intuitively correct sensitivity to floodplain friction over spatially-complex topography. It does, however, incur a prohibitive computation cost at model grid resolutions less than 50 m. This primary research is supplemented by an examination of the data and methods used to apply, and in particular calibrate, distributed flood inundation models in practice. Firstly, different objective functions for evaluating the overall similarity between binary predictions of flood extent and remotely sensed images of inundation patterns are examined. On the basis of the results presented, recommendations are provided regarding the use of various measures for hydrological problems. Secondly, the value of different observational data types typically available for calibrating/constraining model predictions is explored within an extended Generalised Likelihood Uncertainty Estimation (GLUE) framework. A quasi-Bayesian methodology for combining these individual evaluations that overcomes the limitations of calibration against any single measurement source/item is also presented.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Northeastern Qatari coast hydrodynamic modeling for assessment of sensitive ecosystems under anthropogenic and natural stressors

The Northeastern Qatari coast, comprising diverse and sensitive flora and fauna communities (e.g. coral reefs and patches, seagrass meadows and turtles) is expected to undergo changes imposed by anthropogenic stressors (coastal development projects) in the near future. Therefore, the need to study the impacts of such scenarios on the existing ecosystems is pressing. Ecohydrological models are theoretical, mathematical representations of a natural system, made to understand the functionalities of the real ecological system under physical forcing. Using gathered data from sites, ecological associations are inferred and then combined to build a functional ecosystem model that mimics the real environment. These model systems are then used in order to assist the impact assessment of future scenarios on real systems. The aim of this study was to create hydrodynamic simulation along with a sediment transport model for a stretch of coastline off of Jabal Fuwairat. This aim was achieved using GEMSS modeler software, which requires the following data for a proper model (1) spatial data (that is included as shape files imported from ArcGIS), primarily the water body shoreline and bathymetry, additionally the locations, altitudes, and formations of man-made structures; (2) time-based data, that are varying in time (i.e. tidal changes, influx rate and temperature and meteorological data) and (3) Sediment composition. These data were collected and gathered into time varying data files that are loaded into a control file. A hydrodynamic model (HDM) simulating the spatial dynamics of the water was developed, calibrated and validated using field data. Additionally, a sediment transport model (STM) identifying, under present or simulated scenarios, the fate of the suspended sediment in the region and identifying potentially erosion and sedimentation area in the studied coastal zone is proposed. This STM assimilates data about sediment typologies, suspended particulate matter and currents near the seafloor (shear stress). Results from both HDM and STM models demonstrated that the study area is highly dynamic, being mainly controlled by tides and with relatively high shear stress (potential for erosion) in the northern and east-western boundaries. Considering these factors, the present research work intends to understand through a modeling approach the ecohydrological features of this area with special emphasis on the sediment dynamics and potential risks facing the sensitive coral reefs located in the area. This work provides three scenarios of future development that might take place in the area and shows the alteration of the dynamics of water and sediments accordingly. These simulations help the development of recommendations to decision makers for a better management of the considered coastal zone. It also provides a tool that can be replicated in future hydrodynamic studies along the Qatari coastal zone.من المتوقع أن يخضع الساحل الشمالي الشرقي القطري في المستقبل القريب لتغييرات التي تفرضها الضغوطات البشرية )مشاريع التنمية الساحلية( . يتألف هذا الساحل من النباتات المتنوعة والحيوانات حساسة )مثل الشعاب المرجانية ، ومروج الأعشاب البحرية والسلاحف ( لذلك هناك حاجة ملحة إلى دراسة الآثار المترتبة على مثل هذه الثغيرات على النظم الإيكولوجية. النماذج الإيكولوجية ، هي عبارة عن تمثيلات رياضية و نظرية للنظام الطبيعي، التي أدخلت على فهم الخصائص الوظيفية للنظام البيئي الحقيقي تحت تاثيرات فيزيائية معروفة تمثل النظام المدروس . باستخدام البيانات التي تم جمعها من حقول او من الجمعيات البيئية لبناء نموذج النظام البيئي الوظيفي الذي يحاكي البيئة الحقيقية . ثم يتم استخدام هذه النظم كنموذج من أجل مساعدة تقييم تأثير السيناريوهات المستقبلية على الأنظمة الحقيقية . الهدف من هذه الدراسة هو خلق المحاكاة الهيدروديناميكية جنبا إلى جنب مع نموذج نقل الرواسب لتمتد من الساحل قبالة جبل فويرط . وقد تحقق هذا الهدف باستخدام برنامج GEMSS لصناعة النماذج، و الذي يتطلب البيانات التالية للحصول على نموذج السليم 1( البيانات الفضائيه ) كملفات من نظام ( ArcGIS (، الذي يتضمن الخط الساحلي للمنطقة وقياس الأعماق، بالإضافة إلى المواقع، الارتفاعات، و تشكيلات الهياكل التي من صنع الإنسان . . (2) البيانات التي تستند على الوقت، والتي هي متفاوتة في الوقت المناسب )أي تغيرات المد والجزر، ومعدل التدفق ودرجة الحرارة وبيانات الأرصاد الجوية( . (3) تكوين الرواسب. تم صنع النموذج الهيدروديناميكي لمحاكاة ميكانيكيات المياة والتحقق من صحة البيانات بمقارنتها مع بيانات حقليه . بالإضافة إلى ذلك, تم صنع نموذج نقل الرواسب الذي يحدد مصير الرواسب العالقة في المنطقة وتحديد أحتمل حدوث التعرية اوالترسيب في اي منطقة اخرى . أظهرت النتائج لكل من النموذج الهيدروديناميكي والنموذج نقل الرواسب أن منطقة الدراسة هي منطقة ديناميكية للغاية، يتم التحكم بها بشكل رئيسي من قبل المد والجزر وأن احتمال التعريه للرواسب تتزايد في الحدود الشمالية والشرق والغرب . يوفر هذا العمل ثلاثة سيناريوهات للتنميه المستقبلية التي قد تحدث في هذه المنطقة، ويظهر تغيير ديناميكيات المياه والرواسب وفقا لذلك . وفقا لذلك خرجنا بمجموعة من التوصيات لصناع القرار لتحسين إدارة المنطقة الساحلية . كما أنه يوفر الأدوات التي يمكن تكرارها في الدراسات الهيدروديناميكية في المستقبل على طول المنطقة الساحلية القطرية

The BG News April 1, 1982

The BGSU campus student newspaper April 1, 1982.https://scholarworks.bgsu.edu/bg-news/4974/thumbnail.jp

The BG News April 1, 1982

The BGSU campus student newspaper April 1, 1982.https://scholarworks.bgsu.edu/bg-news/4974/thumbnail.jp

Las Vegas Daily Optic, 07-03-1899

https://digitalrepository.unm.edu/lvdo_news/4699/thumbnail.jp