Download or read book Spatial Distribution of Aerosol Optical Thickness Retrieved from SeaWiFS Images by a Neural Network Inversion Over the West African Coast written by Daouda Diouf and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol optical thickness (AOT) was provided by SeaWiFS over oceans from October 1997 to December 2010. Weekly, monthly, and annually maps might help scientifics to better understand climate change and its impacts. Making average of several images to get these maps is not suitable on West African coast. A particularity of this area is that it is constantly traversed by desert dust. The algorithm used by SeaWiFS inverts the reflectance measurements to retrieve the aerosol optical thickness at 865 nm. For the poorly absorbing aerosol optical thickness less than 0.35, the standard algorithm works very well. On the west African coast that is often crossed by desert aerosol plumes characterized by high optical thicknesses. In this paper we study the spatial and temporal variability of aerosols on the West African coast during the period from December 1997 to November 2009 by using neural network inversion. The neural network method we used is mixed method of neuro-variational inversion called SOM-NV. It is an evolution of NeuroVaria that is a combination of a variational inversion and multilayer perceptrons, multilayer perceptrons (MLPs). This work also enables validation of the optical thickness retrieved by SOM-NV with AOT in situ measurements collected at AErosol RObotic NETwork (AERONET) stations.
Download or read book Aerosols written by Konstantin Volkov and published by BoD – Books on Demand. This book was released on 2016-12-28 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosols have a significant impact on technological processes and human activities. In many cases, aerosols are at the core of human health, environmental and technological problems (climate change and air quality). However, aerosols can be successfully used in industry and technology (new materials, fire suppression and fuel delivery). The current scientific status of aerosol modelling and simulation and measurements and some advances in computational techniques, particle measurement technologies and practical applications of aerosols are reviewed and considered in this book. This book also includes a number of case studies focused on analysis of optical thickness and air quality in various regions.
Download or read book In Situ Aerosol Optical Thickness Collected by the SIMBIOS Program 1997 2000 written by Giulietta S. Fargion and published by . This book was released on 2001 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Assessment of a Neural Network Approach for Retrieving Aerosol Properties from Multispectral Multiangle Polarization Measurements written by Alexandra Tsekeri and published by . This book was released on 2012 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantifying the microphysical properties of aerosols is crucial for quantifying global climate forcings. Satellite based aerosol retrievals usually rely on intensity measurements of the scattered light, but this approach has been proven inadequate for retrieving the complex refractive index and shape of aerosols, as well as the contamination from the ground surfaces. It is with these limitations in mind that we plan to improve the quality and scope of aerosol retrievals, by making use of the full capabilities of current and future polarimetric sensor systems. In order to utilize the increased information content on aerosol optical thickness (AOT), size distribution, shape and single scattering albedo (SSA), intrinsically available in multispectral-multiangle polarimetric observations, we make use of suitably constructed neural networks (NNs). We focus our analysis initially on simple retrievals over the ocean, in order to best assess the potential of the NNs as a practical approach and to identify any possible limitations. In particular, we find that, by choosing a suitable combination of inputs and outputs, based on principal component analysis (PCA), we can develop a robust NN retrieval trained on synthetic datasets. We further show the value of using cascaded NNs, to improve retrieval accuracy. Consequently, we demonstrate the potential and limitations of this approach on real aircraft instrument data from the Research Scanning Polarimeter (RSP). Discrepancies in the retrievals are found to be due to limitations from the use of spherical particle assumptions and preliminary efforts to overcome this restriction are identified. It is our belief that the value of these methods, in comparison to existing local inversion schemes, will further increase with the expected magnification of data sizes on future missions, such as the Aerosol-Cloud-Ecosystem (ACE) Mission.
Download or read book Characterizing the Spatial and Temporal Distribution of Aerosol Optical Thickness Over the Atlantic Basin Utilizing GOES 8 Multispectral Data written by and published by . This book was released on 2001 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerosol Surface and Cloud Retrieval Using Passive Remote Sensing Over the Arctic written by Soheila Jafariserajehlou and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The lack knowledge of aerosol optical properties is one of the sources of uncertainty in assessment and projections of the evolution of climate change and the phenomenon of Arctic Amplification. The spatial and temporal change of microphysical, chemical and optical properties of aerosols in the Arctic and the induced effects through direct and indirect radiative forcing of aerosols remain an open question. The cause of this gap in our understanding and therefore in the global aerosol optical thickness (AOT) maps is associated with the difficulty of retrieving aerosol properties over bright surfaces covered with snow and ice. Decoupling a strong surface signal from that of aerosol in the measured top-of-atmosphere reflectance is challenging and still hampered due to remaining unresolved issues in state-of-the-art algorithms. Despite the promising performance of previously-developed methods and ongoing research, there is no published long-term AOT product over polar regions (over land and ocean) to be used for climate studies. In this work, to extend our knowledge about the open issues and improve the existing algorithms, first we focus on the two major obstacles in the retrieval of AOT over snow/ice surfaces: i) cloud identification, and ii) surface properties; Second, we apply the outcome of studying the two mentioned prerequisites to improve the previously-developed aerosol retrieval algorithm called AEROSNOW and create a long-term data record for aerosol optical thickness over the Arctic circle. In the framework of this work, a new cloud identification algorithm called the AATSR/SLSTR Cloud Identification Algorithm (ASCIA) has been developed to screen cloudy scenes in observations of Advanced Along-Track Scanning Radiometer (AATSR) on-board ENVISAT as well as its successor Sea and Land Surface Temperature Radiometer (SLSTR) on-board Sentinel-3. The cloud detection results are verified by comparing them with available cloud products over the Arctic. Furthermore, the cloud product from ASCIA is validated using the ground-based measurements SYNOP, resulting in a promising agreement. In general, ASCIA shows an improved performance in comparison with other algorithms applied to AATSR measurements over snow/ice. For the study of snow surface properties, the reflectance is simulated in a snow-atmosphere system, using the SCIATRAN radiative transfer model, and the results are compared with those of airborne measurements. A sensitivity study is conducted to highlight the importance of having a priori knowledge about snow morphology (size and shape) and atmospheric parameters to minimise the difference between simulated and real world reflectance. The absolute difference between the modelled results and measurements in off-glint regions is generally small and promising. In the final step, we apply the outcome of previous steps in the AEROSNOW algorithm as far as possible within the scope of this work and retrieve AOT over the Arctic circle for the 2002-2012 period with the spatial resolution of 1 km2. The retrieved AOT is validated using ground-based measurements AErosol RObotic NETwork (AERONET). The results of validation are promising and show the successful performance of the algorithm especially during haze episodes. However, in some cases large differences exist between the retrieved AOT and AERONET measurements for which more statistical and physical analysis are necessary to better understand the cause. Nevertheless, the long-term data record and validation produced hold significant value as are the first attempt to better understand the role of aerosols in the Arctic Amplification over land and ocean on the full Arctic scale.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Real time Coastal Observing Systems for Marine Ecosystem Dynamics and Harmful Algal Blooms written by Babin, Marcel and published by UNESCO. This book was released on 2008-06-05 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proliferation of harmful phytoplankton in marine ecosystems can cause massive fish kills, contaminate seafood with toxins, impact local and regional economies and dramatically affect ecological balance. Real-time observations are essential for effective short-term operational forecasting, but observation and modelling systems are still being developed. This volume provides guidance for developing real-time and near real-time sensing systems for observing and predicting plankton dynamics, including harmful algal blooms, in coastal waters. The underlying theory is explained and current trends in research and monitoring are discussed.Topics covered include: coastal ecosystems and dynamics of harmful algal blooms; theory and practical applications of in situ and remotely sensed optical detection of microalgal distributions and composition; theory and practical applications of in situ biological and chemical sensors for targeted species and toxin detection; integrated observing systems and platforms for detection; diagnostic and predictive modelling of ecosystems and harmful algal blooms, including data assimilation techniques; observational needs for the public and government; and future directions for research and operations.
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 Atmospheric Aerosols written by Claudio Tomasi and published by John Wiley & Sons. This book was released on 2017-03-20 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ein Blick auf die morphologischen, physikalischen und chemischen Eigenschaften von Aerosolen aus den unterschiedlichsten natürlichen und anthropogenen Quellen trägt zum besseren Verständnis der Rolle bei, die Aerosolpartikel bei der Streuung und Absorption kurz- und langwelliger Strahlung spielen. Dieses Fachbuch bietet Informationen, die sonst schwer zu finden sind, und vermittelt ausführlich die Kenntnisse, die erforderlich sind, um die mikrophysikalischen, chemischen und Strahlungsparameter zu charakterisieren, die bei der Wechselwirkung von Sonnen- und Erdstrahlen so überaus wichtig sind. Besonderes Augenmerk liegt auf den indirekten Auswirkungen von Aerosolen auf das Klima im Rahmen des komplexen Systems aus Aerosolen, Wolken und der Atmosphäre. Auch geht es vorrangig um die Wirkungen natürlicher und anthropogener Aerosole auf die Luftqualität und die Umwelt, auf die menschliche Gesundheit und unser kulturelles Erbe. Mit einem durchgängig lösungsorientierten Ansatz werden nicht nur die Probleme und Gefahren dieser Aerosole behandelt, sondern auch praktikable Lösungswege aufgezeigt.
Download or read book Bio optical Modeling and Remote Sensing of Inland Waters written by Deepak R. Mishra and published by Elsevier. This book was released on 2017-04-28 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bio-optical Modeling and Remote Sensing of Inland Waters presents the latest developments, state-of-the-art, and future perspectives of bio-optical modeling for each optically active component of inland waters, providing a broad range of applications of water quality monitoring using remote sensing. Rather than discussing optical radiometry theories, the authors explore the applications of these theories to inland aquatic environments. The book not only covers applications, but also discusses new possibilities, making the bio-optical theories operational, a concept that is of great interest to both government and private sector organizations. In addition, it addresses not only the physical theory that makes bio-optical modeling possible, but also the implementation and applications of bio-optical modeling in inland waters. Early chapters introduce the concepts of bio-optical modeling and the classification of bio-optical models and satellite capabilities both in existence and in development. Later chapters target specific optically active components (OACs) for inland waters and present the current status and future direction of bio-optical modeling for the OACs. Concluding sections provide an overview of a governance strategy for global monitoring of inland waters based on earth observation and bio-optical modeling. Presents comprehensive chapters that each target a different optically active component of inland waters Contains contributions from respected and active professionals in the field Presents applications of bio-optical modeling theories that are applicable to researchers, professionals, and government agencies
Download or read book On the satellite retrieval of aerosol optical thickness over polar regions written by C. KERGOMARD and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Global and Regional Trends of Aerosol Optical Thickness Derived Using Satellite and Ground based Observations written by Jongmin Yoon and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerosol Remote Sensing written by Jacqueline Lenoble and published by Springer Science & Business Media. This book was released on 2013-02-11 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a much needed explanation of the basic physical principles of radiative transfer and remote sensing, and presents all the instruments and retrieval algorithms in a homogenous manner. The editors provide, for the first time, an easy path from theory to practical algorithms in one easily accessible volume, making the connection between theoretical radiative transfer and individual practical solutions to retrieve aerosol information from remote sensing, and providing the specifics and intercomparison of all current and historical retrieval methods.
Download or read book Advanced Remote Sensing written by Shunlin Liang and published by Academic Press. This book was released on 2012-12-06 with total page 821 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Remote Sensing is an application-based reference that provides a single source of mathematical concepts necessary for remote sensing data gathering and assimilation. It presents state-of-the-art techniques for estimating land surface variables from a variety of data types, including optical sensors such as RADAR and LIDAR. Scientists in a number of different fields including geography, geology, atmospheric science, environmental science, planetary science and ecology will have access to critically-important data extraction techniques and their virtually unlimited applications. While rigorous enough for the most experienced of scientists, the techniques are well designed and integrated, making the book’s content intuitive, clearly presented, and practical in its implementation. Comprehensive overview of various practical methods and algorithms Detailed description of the principles and procedures of the state-of-the-art algorithms Real-world case studies open several chapters More than 500 full-color figures and tables Edited by top remote sensing experts with contributions from authors across the geosciences
Download or read book Earth Observations in Support of Global Water Quality Monitoring written by Steven Greb and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Remote Sensing of Tropospheric Composition from Space written by John P. Burrows and published by Springer Science & Business Media. This book was released on 2011-01-15 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: The impact of anthropogenic activities on our atmospheric environment is of growing public concern and satellite-based techniques now provide an essential component of observational strategies on regional and global scales. The purpose of this book is to summarise the state of the art in the field in general, while describing both key techniques and findings in particular. It opens with an historical perspective of the field together with the basic principles of remote sensing from space. Three chapters follow on the techniques and on the solutions to the problems associated with the various spectral regions in which observations are made. The particular challenges posed by aerosols and clouds are covered in the next two chapters. Of special importance is the accuracy and reliability of remote sensing data and these issues are covered in a chapter on validation. The final section of the book is concerned with the exploitation of data, with chapters on observational aspects, which includes both individual and synergistic studies, and on the comparison of global and regional observations with chemical transport and climate models and the added value that the interaction brings to both. The book concludes with scientific needs and likely future developments in the field, and the necessary actions to be taken if we are to have the global observation system that the Earth needs in its present, deteriorating state. The appendices provide a comprehensive list of satellite instruments, global representations of some ancillary data such as fire counts and light pollution, a list of abbreviations and acronyms, and a set of colourful timelines indicating the satellite coverage of tropospheric composition in the foreseeable future. Altogether, this book will be a timely reference and overview for anyone working at the interface of environmental, atmospheric and space sciences.
