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Статті в журналах з теми "Air-land interaction"
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Grachev, Andrey A., Laura S. Leo, Harindra J. S. Fernando, Christopher W. Fairall, Edward Creegan, Byron W. Blomquist, Adam J. Christman, and Christopher M. Hocut. "Air–Sea/Land Interaction in the Coastal Zone." Boundary-Layer Meteorology 167, no. 2 (December 5, 2017): 181–210. http://dx.doi.org/10.1007/s10546-017-0326-2.
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Rutgersson, Anna, Heidi Pettersson, Erik Nilsson, Hans Bergström, Marcus B. Wallin, E. Douglas Nilsson, Erik Sahlée, Lichuan Wu, and E. Monica Mårtensson. "Using land-based stations for air–sea interaction studies." Tellus A: Dynamic Meteorology and Oceanography 72, no. 1 (December 9, 2019): 1–23. http://dx.doi.org/10.1080/16000870.2019.1697601.
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Cholaw, Bueh, Ji Liren, Sun Shuqing, and Cui Maochang. "EA WM-Related Air-Sea-Land Interaction and the Asian Summer Monsoon Circulation." Advances in Atmospheric Sciences 18, no. 5 (September 2001): 659–73. http://dx.doi.org/10.1007/bf03403492.
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Ahmad, Mohsin Hasnain, Usman Azhar, Syed Ashraf Swati, and Zeshan Inam. "Interaction between Population and Environmental Degradation." Pakistan Development Review 44, no. 4II (December 1, 2005): 1135–50. http://dx.doi.org/10.30541/v44i4iipp.1135-1150.
Повний текст джерелаАнотація:
Economic development and population growth in the poor areas of the earth is a subject of an essential concern for the environmental economists. Developing countries are facing and suffering by the serious problem of high population growth which is causing environmental degradation. A rapidly growing population exerts pressure on agricultural land and raises demand for food and shelter which encourages the conversion of forest land for agricultural and residential uses, now we know that growing population is a major cause of air, water, and solid waste pollution. The world population was 2.52 billion in the year 1950, which increased to 6.06 billion in 2000 and is likely to reach 8.3 billion by the year 2030. While the population size will remain almost stationary in the economically developed part of the world, around 1.2 billion, during the same period population is likely to grow in the less developed regions. This is likely to pose challenges for the economic growth and pressure on environmental resources in the developing countries. Furthermore, most of the population growth in the developing countries is likely to be concentrated in the urban areas. This has implication for increased demand for energy and water resources in the urban areas. This will also pose challenges for the management of increased solid waste, air and water pollution. One of the striking experiences of the developing
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Cai, Hao, and Zheng Mao. "Research and Application of Display System of Component-Based Virtual Instrument for Land and Air Platforms." Journal of Physics: Conference Series 2218, no. 1 (March 1, 2022): 012083. http://dx.doi.org/10.1088/1742-6596/2218/1/012083.
Повний текст джерелаАнотація:
Abstract With the diversified combat missions in the new era and the development of industrialization, the demand for military and civilian equipment continues to increase, and the development and upgrade standards of land-air dual-use platforms must also move toward standardization. As the core of information visualization and control standardization, the component-based virtual instrument display platform is an important part of the integrated information display system of the land-air platform. The component display platform takes the optimization of the research and development, design and maintenance of the land and air mobile platform as the starting point, and at the same time meets the needs of wartime and meets the development trend of future informatization. It adopts engineering design ideas, hierarchical software layout and componentized ideas of man-machines. The concepts of interaction design are based on componentization techniques, serial communication, data dictionaries, pattern transformations, etc. A comprehensive information display platform aims to increase software productivity, reduce development costs and degree of coupling, and meet human-computer interaction as well as user-friendliness requirements.
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Vorovka, Volodymyr. "System-forming factors of the organization of coastal paradynamic landscape systems." Physical Geography and Geomorphology 89, no. 1 (2018): 60–69. http://dx.doi.org/10.17721/phgg.2018.1.09.
Повний текст джерелаАнотація:
The basis of system-forming factors of the organization of coastal paradynamic landscape system is composed of natural factors associated with characteristics of geographic distribution of the coast, its configuration, tectonic, morphometric, hydrological, climatic and other indices, along with characteristics of the surrounding land. Paradynamic interactions are formed on the basis of exchange of matter, energy and information between spatially adjacent contrasting complexes. The main system-forming factor of the coastal paradynamic landscape system is the relationship of its structural complexes with various types of spatial dynamics and corresponding processes, distinguished into three main streams - matter, energy and information, caused by the simultaneous interaction of the atmosphere, hydrosphere, lithosphere, biosphere and their specificity. A complex nature of the interaction between natural landscape complexes and their components among themselves in the coastal zone was revealed. Characteristics of the horizontal interaction between marine waters and the surrounding land, river mouth and adjacent sea area, interactions in the system "sea-river-liman" were found out. Main processes of the vertical interaction between the environments were revealed: the land and sea, air and water, bottom layers of water and the bottom itself. The principal scheme of energy flows in the coastal zone was developed. The paradynamic interaction is based on the exchange of matter, energy and information between spatially adjacent contrasting systems. The importance of this type of research is explained by the need to take into account the revealed interactions for the formation of effective system of integrated management of the coastal zone to ensure further optimization of its structure and functioning.
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Misra, Vasubandhu. "Coupled Air, Sea, and Land Interactions of the South American Monsoon." Journal of Climate 21, no. 23 (December 1, 2008): 6389–403. http://dx.doi.org/10.1175/2008jcli2497.1.
Повний текст джерелаАнотація:
Abstract The dominant interannual variation of the austral summer South American monsoon season (SAM) is associated with El Niño–Southern Oscillation (ENSO). Although this teleconnection provides a basis for the seasonal predictability of SAM, it is shown that the conventional tier-2 modeling approach of prescribing observed sea surface temperature (SST) is inappropriate to capture this teleconnection. Furthermore, such a forced atmospheric general circulation model (AGCM) simulation leads to degradation of the SAM precipitation variability. However, when the same AGCM is coupled to an ocean general circulation model to allow for coupled air–sea interactions, then this ENSO–SAM teleconnection is reasonably well simulated. This is attributed to the role of air–sea coupling in modulating the large-scale east–west circulation, especially associated with Niño-3 SST anomalies. It is also shown that the land–atmosphere feedback in the SAM domain as a result of the inclusion of air–sea coupling is more robust. As a consequence of this stronger land–atmosphere feedback the decorrelation time of the daily rainfall in the SAM region is prolonged to match more closely with the observed behavior. A subtle difference in the austral summer seasonal precipitation anomalies between that over the Amazon River basin (ARB) and the SAM core region is also drawn from this study in reference to the influence of the air–sea interaction. It is shown that the dominant interannual precipitation variability over the ARB is simulated both by the uncoupled and coupled (to OGCM) AGCM in contrast to that over the SAM core region in southeastern Brazil.
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Pysarenko, L. A., and S. V. Krakovska. "Main directions in modern research of interaction between climate and land use/land cover changes." Ukrainian hydrometeorological journal, no. 25 (July 16, 2020): 38–52. http://dx.doi.org/10.31481/uhmj.25.2020.04.
Повний текст джерелаАнотація:
The purpose of the research is to analyse and assess existing approaches in investigation of interconnections between climate and underlying surface. Land use/land cover (LULC) influences climate formation via physical and chemical properties (albedo, roughness, height, chemical composition etc.). Climate in its turn affects land cover by means of meteorological parameters (air temperature and humidity, precipitation, wind etc.) and causes both cyclic and irreversible changes in land cover. In addition, anthropogenic factors exacerbate surface-climate interactions through? for example, LULC change that usually causes an additional release of chemical compounds. The paper distinguishes three main directions of the “climate - LULC” interactions research that is conducted mainly with application of satellite monitoring products, observation dataset, geographic information systems (GIS) and numerical modelling. The first direction implies monitoring and research of cyclic changes and transformation of LULC influenced by natural and anthropogenic factors, using different GIS-based satellite and surface meteorological observation databases. Despite significant technical progress and great amount of studies conducted for detecting dynamics of LULC change for different time intervals, the problems of dealing with cloudiness and shadows from orographic and other objects still remain. The second direction investigates the influence of LULC change on the chemical composition in the atmospheric boundary layer and on the regional climate. Numerous researches were dedicated to the influence of different kinds of surface such as forests, grasslands, croplands, urban areas etc. on climate characteristics and also on fluxes, for example, CO2. The effect of midlatitude forests on climate remains to be one of the challenging and urgent issues. The third direction relates to LULC change modelling and regional climate modelling. For the last decade a spatial resolution of models was considerably increased and, as a result, representation of interaction between atmosphere and land improved. Online integrated numerical atmospheric models are found as the most promising ones. They include "meteorological parameters – atmospheric chemical composition" feedbacks and can consider LULC on global and regional scales. However, some issues still need improvement, namely radiative transfer, cloud microphysics, cloud-aerosol-precipitation interactions, as well as parametrizations of some types of land and their interaction with the atmospheric boundary layer.
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Duan, Zexia, Zhiqiu Gao, Qing Xu, Shaohui Zhou, Kai Qin, and Yuanjian Yang. "A benchmark dataset of diurnal- and seasonal-scale radiation, heat, and CO2 fluxes in a typical East Asian monsoon region." Earth System Science Data 14, no. 9 (September 8, 2022): 4153–69. http://dx.doi.org/10.5194/essd-14-4153-2022.
Повний текст джерелаАнотація:
Abstract. A benchmark dataset of radiation, heat, and CO2 fluxes is crucial to land–atmosphere interaction research. Due to rapid urbanization and the development of agriculture, the land–atmosphere interaction processes over the Yangtze River Delta (YRD) of China, which is a typical East Asian monsoon region, are becoming various and complex. To understand the effects of various land cover changes on land–atmosphere interactions in this region, a comprehensive long-term (2011–2019) in situ observation campaign, including 30 min resolution meteorological variables (air temperature, humidity, pressure, wind speed, and wind direction), surface radiative flux, turbulent heat flux, and CO2 flux, was conducted at four sites with two typical surface types (i.e., croplands and suburbs) in the YRD. Analysis of the dataset showed that all four radiation components, latent heat flux, sensible heat flux, soil heat flux, and CO2 flux varied seasonally and diurnally at the four sites. Surface energy fluxes exhibited great differences among the four sites. On an annual basis, for the two cropland sites, the dominant consumer of net radiation was latent heat flux. For the two suburban sites, in contrast, latent heating dominated from April to November, whereas sensible heating dominated during the other months. Our present work provides convincing evidence that the dataset has potential for multiple research fields, including studying land–atmosphere interactions, improving boundary layer parameterization schemes, evaluating remote sensing algorithms, validating carbon flux modeling and inversion, and developing climate models for typical East Asian monsoon regions. The dataset is publicly available at https://doi.org/10.5281/zenodo.6552301 (Duan et al., 2022).
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Shahraki, N., and M. Turkay. "Analysis of interaction among land use, transportation network and air pollution using stochastic nonlinear programming." International Journal of Environmental Science and Technology 11, no. 8 (April 10, 2014): 2201–16. http://dx.doi.org/10.1007/s13762-014-0566-3.
Повний текст джерелаДисертації з теми "Air-land interaction"
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Hirdman, David. "Sensitivity Analysis of the Mesoscale Air Pollution Model TAPM." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303877.
Повний текст джерелаАнотація:
Known problems with the air pollution model, TAPM’s meteorological predictions over the Canterbury Plains, New Zealand, has been its lack of ability to simulate low nocturnal stagnant wind speeds, certain wind field directions as well as greatly overestimating the sensible heat flux. The aim of this thesis has been to reduce these known disagreements along with other meteorological parameters in attempt to optimize TAPM’s predictions for New Zealand conditions. The methodology used to obtain better agreement with observational data during a four-day period (1-4 of August 2000) was to modify certain initial parameters. These parameters were the deep soil volumetric moisture content, the deep soil temperature, the sea surface temperature, the synoptic pressure gradient scaling factor, and to include rain processes or not in the simulations. It is found that including rain processes and increasing the deep soil volumetric moisture content (at least during wintertime) do improve the simulations performance.Från tidigare studier med luftföroreningsmodellen TAPMs meteorologiska prognoser över Canterburys slätter, i Nya Zeeland, har man funnit problem. Dess brister har bestått i svårigheter att simulera de nattetid svaga och stagnerande vindhastigheter, vissa riktningar i vindfältet samt grov överskattning av det sensibla värmaflödet. Målet med denna rapport har varit att reducera dessa kända avvikelser tillsammans med andra meteorologiska parametrar i ett försök att optimera TAPMs prognoser för förhållandena över Nya Zeeland. Metodiken som används för att uppnå bättre överensstämmelse med observationsdatan från en fyradagarsperiod, 1-4 augusti år 2000, var att modifiera vissa specifika initieringparametrar. Dessa parametrar var den djupgående markfuktigheten, den djupgående marktemperaturen, havsytans temperatur, det synoptiska tryckets skalningsfaktor. Det undersöktes också om man skulle inkludera nederbördsprocesser eller inte i simuleringarna. Resultaten visade att en inkludering av nederbördsprocesser samt en ökning av den djupa markfuktigheten (åtminstone vintertid) verkar förbättra kvalitéten på simuleringarnas resultat.
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Acosta, Navarro Juan Camilo. "Anthropogenic influence on climate through changes in aerosol emissions from air pollution and land use change." Doctoral thesis, Stockholms universitet, Institutionen för miljövetenskap och analytisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-137077.
Повний текст джерелаАнотація:
Particulate matter suspended in air (i.e. aerosol particles) exerts a substantial influence on the climate of our planet and is responsible for causing severe public health problems in many regions across the globe. Human activities have altered the natural and anthropogenic emissions of aerosol particles through direct emissions or indirectly by modifying natural sources. The climate effects of the latter have been largely overlooked. Humans have dramatically altered the land surface of the planet causing changes in natural aerosol emissions from vegetated areas. Regulation on anthropogenic and natural aerosol emissions have the potential to affect the climate on regional to global scales. Furthermore, the regional climate effects of aerosol particles could potentially be very different than the ones caused by other climate forcers (e.g. well mixed greenhouse gases). The main objective of this work was to investigate the climatic effects of land use and air pollution via aerosol changes. Using numerical model simulations it was found that land use changes in the past millennium have likely caused a positive radiative forcing via aerosol climate interactions. The forcing is an order of magnitude smaller and has an opposite sign than the radiative forcing caused by direct aerosol emissions changes from other human activities. The results also indicate that future reductions of fossil fuel aerosols via air quality regulations may lead to an additional warming of the planet by mid-21st century and could also cause an important Arctic amplification of the warming. In addition, the mean position of the intertropical convergence zone and the Asian monsoon appear to be sensitive to aerosol emission reductions from air quality regulations. For these reasons, climate mitigation policies should take into consideration aerosol air pollution, which has not received sufficient attention in the past.
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Astudillo, Orlando. "Rôle des interactions océan-atmosphère-continent sur la dynamique de la couche limite marine dans la région d'upwelling du Chili central." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30360.
Повний текст джерелаАнотація:
Les systèmes de courant de bords est (EBUS) sont les régions océaniques des latitudes tropicales à moyennes le long des côtes ouest des continents. Ils abritent des écosystèmes marins très productifs en raison de la circulation atmosphérique de surface dirigée vers l'équateur qui font remonter des eaux profondes froides (upwelling) enrichies en éléments nutritifs à l'origine de la vie marine le longde la côte. Si les processus océaniques fondamentaux de l'upwelling côtier sont bien connus (transport et pompage d'Ekman), la modélisation océanique des EBUS reste problématique en raison des difficultés pour prendre en compte de manière réaliste des phénomènes à fine échelle spatiale dans la zone de transition entre le littoral et l'océan du large. Dans cette thèse, nous nous sommes concentrés sur le système d'upwelling dit de Humboldt (côtes du Pérou et du Chili) et sur l'influence des caractéristiques méso-échelles des vents près de la côte, en particulier la décroissance vers la cotes du vent (appelé "drop-off") qui détermine l'importance relative des processus d'Ekman, et donc, la structure spatiale de la zone d'upwelling. Une approche combinée basée sur l'analyse de données satellitaires et sur la modélisation régionale, océanique et atmosphérique, est utilisée pour étudier la sensibilité de la circulation océanique le long de la côte Chili central aux caractéristiques du drop-off. Dans un premier temps, la circulation atmosphérique de surface moyenne à saisonnière le long du littoral du Pérou et du Chili est documentée pour la première fois à partir des données altimétriques de quatre missions satellites (ENVISAT, JASON1, JASON2 et SARAL). L'analyse révèle l'existence d'une réduction marquée de la vitesse du vent le long de la côte, bien que le taux de réduction varie en fonction de la latitude. Malgré la répétitivité relativement faible des satellites, nous montrons que les données altimétriques permettent néanmoins d'échantillonner le cycle saisonnier du drop-off. L'estimation de l'upwelling côtier à partir de ces données suggère que le pompage d'Ekman tend en moyenne à dominer par rapport au transport d'Ekman le long de la côte péruvienne, alors que le long de la côte chilienne, le transport d'Ekman est le processus dominant. Dans un second temps, un modèle atmosphérique régional (WRF) à différentes résolutions horizontales (36 km, 12 km et 4 km) dans une configuration imbriquée zoomée sur la région centrale du Chili a été développé afin de produire des champs atmosphériques présentant des caractéristiques différentes du drop-off. Les solutions du modèle atmosphérique sont d'abord évaluées par rapport aux observations, indiquant un plus grand réalisme près de la côte que les réanalyses atmosphériques. Le rotationnel du vent cyclonique simulé le long de la côte associé au drop-off présente des échelles transversales comprises entre 8 et 45 km avec une variabilité latitudinale significative, en accord avec les vents altimétriques. Lorsque la résolution du modèle est augmentée, le drop-off est généralement d'autant plus confiné à la côte et le modèle indique une saisonnalité marquée avec un maximum d'intensité au printemps-automne. La contribution relative de la divergence côtière et du pompage d'Ekman présente une modulation latitudinale liée aux détails de l'orographie et de la ligne de côteEastern Boundary Upwelling Systems (EBUS) are the tropical to mid-latitudes oceanic regions along the west coast of the continents. They host very productive marine ecosystems owing to the mean equatorward low-level atmospheric circulation that uplifts cool subsurface nutrient-enriched waters that trigger marine life along the coast. While the fundamental oceanic processes behind such process are well known (i.e. Ekman transport and pumping), the oceanic modeling of the EBUS has remained problematic owing to difficulties in accounting realistically for phenomena at fine spatial scales in the transition zone between the littoral and the off-shore ocean. In this thesis we have focused on the Peru-Chile Upwelling System (so-called Humboldt system) and on the influence of the cross-shore mesoscale features of the winds near the coast, particularly the shoreward wind drop-off, which determinate the relative importance of the Ekman processes, and thus, the spatial and temporal structure of the upwelling. A combined approach based on satellite data analysis and regional modeling, both oceanic and atmospheric, is used to investigate the sensitivity of the oceanic circulation along the coast of central Chile to the characteristics of the wind drop-off. As a first step, the mean to seasonal near-shore surface atmospheric circulation along the coast of Peru and Chile is documented for the first time based on the altimeter data from four satellite missions (ENVISAT, JASON1, JASON2 and SARAL). The analysis reveals the existence of a marked shoreward reduction in the wind speed all along the coast, although the reduction rate is latitudinally dependent. Despite the relatively weak repetitivity of the satellites, it is shown that the altimetric data are able to sample the seasonal cycle of the wind drop-off at some locations. The estimate of coastal upwelling from these data suggests that Ekman pumping tends on average to dominate with respect to Ekman transport over the Peruvian coast, whereas over the central-Chilean coast, the Ekman transport is the dominant process. In a second step, a regional atmospheric model (WRF) at different horizontal resolutions (36km, 12km and 4km) in a nested configuration zoomed over the central-Chile region was developed in order to produce atmospheric fields with different characteristics of the wind-stress curl (drop-off) along the coast. The atmospheric model solutions are first evaluated against the satellite observations, showing a much larger realism than atmospheric Reanalyses near the coast. In particular, the simulated cyclonic wind curl along the coast related to the wind drop-off exhibit length scales between 8 and 45 km with a significant latitudinal variability, which is in agreement with the altimetric winds. The higher model resolution, the more confined to the coast the wind drop-off, with the latter evidencing a marked seasonality with a maximum intensity in spring-fall and minimum in winter. The relative contribution of the coastal divergence and Ekman pumping exhibits a latitudinal modulation linked to details in the orography and coastlines
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Potard, Kevin. "Les émissions de composés organiques volatiles (COVs) des sols dans les paysages agricoles : identification des sources et incidences sur la qualité de l'air." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B058/document.
Повний текст джерелаАнотація:
Les composés Organiques Volatils (COVs) sont des gaz carbonés rares, émis en faible concentration depuis les surfaces continentale et marine vers l’atmosphère. Très réactifs, ces composés sont impliqués dans la chimie atmosphérique et sont au cœur de nombreuses problématiques environnementales actuelles telles que le changement climatique lié aux gaz à effet de serre, la qualité de l’air et les rétroactions sur le fonctionnement des écosystèmes. Les couverts végétaux terrestres étaient jusqu’alors identifiés comme les sources principales de COVs d’origine biogénique. Mais, de récentes études suggèrent que les sols pourraient constituer des sources majeures de COVs. Or dans les paysages anthropisés agricoles, les sols sont l’objet d’usages et de gestions divers et variés et sont susceptibles de modifier qualitativement et quantitativement les patrons d’émissions de COVs. Paradoxalement, les sols d’agrosystèmes ont fait l’objet de peu d’inventaires de leurs émissions de COVs. La rareté des connaissances sur la contribution des sols d’agrosystèmes dans les émissions de COVs a motivé ce travail de thèse dans lequel trois objectifs ont été poursuivis : i) inventorier les spectres et quantifier les flux de COVs émis par les sols dans les paysages agricoles, ii) déterminer le rôle des microorganismes du sol dans les émissions et iii) identifier les déterminants abiotiques régulant les émissions de COVs par les sols. Une première partie du travail a consisté à analyser les dynamiques temporelles d’émissions de COVs sur le terrain, dans deux sites observatoires représentatifs du paysage agricole Breton : le site EFELE (SOERE-PRO) comprenant des sols cultivés soumis à des pratiques de fertilisation contrastées, et la Zone Atelier Armorique (ZAAr) comprenant des prairies permanentes fertilisées et des prairies humides caractérisées par un faible degré d’anthropisation. La deuxième partie du travail a été menée en laboratoire pour expliciter et compléter les observations de terrain, deux séries d’expérimentations en laboratoire ont été réalisées permettant de manipuler, i) la source de carbone organique du sol via l’apport de différentes molécules modèles, ii) les communautés microbiennes par la transplantation de communautés microbiennes naturelles dans trois sols distincts. Cette étude aura permis de montrer, en laboratoire et sur le terrain, qu’un sol émet une quarantaine de masses dont seules quelques-unes (1 à 4) sont dominantes. Ces spectres de COVs sont par ailleurs spécifiques des usages des sols (culture vs prairie) et des pratiques de fertilisation. Nous montrons aussi : i) qu’il existe une temporalité des émissions de COVs par les sols allant de 22 à 167 μg de COVs par m−2 h−1, la période hivernale étant la moins émissive et que ii) s’ajoute que certaines pratiques de fertilisation, comme l’apport de lisier de porc, induisent un flux de méthanol pouvant atteindre jusqu’à 10 fois celui qui est observé par les sols amendés avec du digestat de lisier de porc. Concernant, le rôle des microorganismes du sol dans la production de COVs, nous démontrons que le spectre de COVs n’est pas représentatif de la diversité phylogénétique de la communauté du sol mais plutôt de l’activité métabolique des microorganismes actifs. S’agissant de l’exploration des déterminants abiotiques susceptibles de réguler les émissions, nos résultats suggèrent que l’ajout de molécules organiques au sol, induit un changement rapide dans le spectre de COVs émis par le sol. Cette modification est dépendante du degré de polymérisation de la molécule apportée. Pour conclure, l’approche intégrative et interdisciplinaire mise en œuvre dans ce travail de thèse a permis d’accroître les connaissances sur les émissions de COVs biogéniques par les sols. L’ensemble des recherches suggère que les émissions de COVs par les sols ne sont pas négligeables. Leur position dans les cycles biogéochimiques nécessite leur intégration dans les scenarii futurs des changements globauxVolatile Organic Compounds (VOCs) are trace carbonaceous gases emitted in low concentrations from the continental and marine surfaces to the atmosphere. Highly reactive, these compounds are involved in atmospheric chemistry and are at the heart of many current environmental issues such as climate change related to greenhouse gases, air quality and feedback on the functioning of ecosystems. Terrestrial plant cover was previously identified as the main source of VOCs of biogenic origin. But recent studies suggest that soils could be major sources of VOCs. However, in agricultural anthropogenic landscapes, soils are subject to various and varied uses and management and are likely to modify qualitatively and quantitatively the patterns of VOC emissions. Paradoxically, agrosystem soils have been the subject of few inventories of their VOC emissions. The scarcity of knowledge on the contribution of agrosystems soils in VOC emissions motivated this work of thesis in which three objectives were pursued : i) inventory the spectra and quantify the VOCs fluxes emitted by soils in agricultural landscapes (ii) to determine the role of soil microorganisms in emissions and (iii) to identify the abiotic determinants controlling VOC emissions by soils. A first part of the work has consisted in analyzing the temporal dynamics of VOCs emissions in the field, in two observatory sites representative of the Britain agricultural landscape : the EFELE site (SOERE-PRO) comprising cultivated soils subjected to contrasting fertilization practices, and the Zone Atelier Armorique (ZAAr) including fertilized permanent meadows and wet meadows characterized by a low degree of anthropization. The second step of the work was conducted in the laboratory to clarify and complete the field observations, two series of laboratory experiments were conducted to manipulate, i) the soil organic carbon source via the input of different model molecules (ii) microbial communities by transplanting natural microbial communities into three distinct soils. This study has generated technical advances and produced entirely new results concerning both the characterization of spectra and the quantification of biogenic VOC fluxes emitted by soils. Thus, we show, in the laboratory and in the field, that a soil emits about forty masses of which only a few (1 to 4) are dominant. These VOC spectra are also specific to land uses (crop vs meadow) and fertilization practices. We also show that : i) there is a temporality of VOC emissions by soils ranging from 22 to 167 μg of VOCs per m−2 h−1, the winter period is the least emissive and ii) adds that some fertilization practices, such as pig slurry, induce a flux of methanol up to 10 times that observed by soils amended with methanised pig slurry. Regarding the role of soil microorganisms in VOCs production, we demonstrate that the VOCs spectrum is not representative of the phylogenetic diversity of the soil community but rather of the metabolic activity of active microorganisms. As for the exploration of abiotic determinants that can regulate emissions, our results suggest that the addition of organic molecules to the soil induces a rapid change in the VOC spectrum emitted by the soil, ranging from a few hours to a few days after intake. This modification is dependent on the degree of polymerization of the molecule provided. All research suggests that VOC emissions by soils are not negligible. Their key position in terms of issues requires to be of greater interest and to take them into account in future scenarios of global changes (climate and land uses), especially with regard to emerging practices of soil management in connection with the ecological transition initiated in agriculture. Similarly, the consideration of VOCs emissions in the biogeochemical cycles of carbon and that of nitrogen to better understand the functioning of ecosystems is also discussed in this document
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Chien, Shou-Hung, and 簡碩宏. "Modeling Air-Land-Sea Interaction using Regional Climate System Model (RCSM) in Monterey Bay, CA." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/13722498626719110907.
Повний текст джерелаАнотація:
碩士臺灣大學
大氣科學研究所
98
Air-land-sea interaction in the vicinity of Monterey Bay, CA is simulated and investigated using a Regional Climate System Model (RCSM). Several coastal processes and submesoscale features can be fully resolved using the RCSM while these processes and features are poorly represented in the state-of-the-art global climate model, resulting in significant and systematic biases in the long term climate integration. The current RCSM couples the Weather Research and Forecast with Community Land Model version3 (WRFCLM3) and a full function coastal ocean model, which is based on the non-hydrostatic Monterey Bay Area Regional Model (MBARM). Our model results show the importance of detailed ocean feedback due to unique coastal dynamic. The comparison with observation indicates the requirement of accurate representation of ocean surface. In the ocean, the coastal upwelling and submesoscale gyres are well-simulated in the RCSM. The daily sea (land) breeze circulations and commonly-seen Santa Cruz Eddy (SCE) are fully resolved resulting from the sea surface temperature feedback and adequate resolution in the coastal margin.
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Carlsson, Björn. "Evaluation of the Inertial Dissipation Methodover Land." Thesis, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303151.
Повний текст джерелаАнотація:
The focus was to evaluate the Inertial Dissipation Method (IDM) over land duringunstable conditions. This was done by comparing the friction velocity, u*, from theeddy-correlation method (ECM) with u* from IDM. The result can be used to see ifIDM can rely on its assumptions, since the surface-layer theory is more fulfilled overland, where we for example do not have wave influence. The measurements weretaken from the flat agricultural site Marsta, 8 km north of Uppsala, Sweden. The result shows that IDM works well over land (relative standard deviation of about 10 %). For weakly unstable stratification, it is enough to use an assumption of neutralconditions in the IDM calculations. If it is more unstable, one should include theinfluence of stability and also include an imbalance term. The imbalance term isintroduced implicitly by varying the effective Kolmogorov’s constant with stability.The effective Kolmogorov’s constant used here, varied from 0.50 up to above 0.80. To calculate u* using IDM, a first estimation of u* was calculated from aparameterised drag coefficient CD. Also, to imitate the measuring setup on a movingplatform on the sea, the stability parameter, z/L, was calculated using a bulkestimatedheat flux. The large scatter showed that it is important that theparameterisations of CD and the heat flux are good. One can conclude that the IDM as a method to determine turbulent fluxes over landworks satisfactory. The larger scatter over sea is probably an effect of sea waveinfluence, even though the sea surface is considered more homogeneous and theconditions more stationary.Syftet var att utvärdera inertial-dissipationsmetoden (IDM) över land under instabilaförhållanden. Detta gjordes genom att jämföra friktionshastigheten, u* , från eddycorrelation-metoden (ECM) med u* från IDM. Resultaten kan användas till att sehuruvida man kan använda de antaganden som IDM vilar på. Ytskiktsteorin ärtroligen mer uppfylld över land, eftersom det t.ex. inte finns något våginflytande.Mätningarna är gjorda i Marsta, som ligger i ett flackt jordbrukslandskap, 8 km norrom Uppsala. Resultatet visar att IDM fungerar tillfredställande över land (relativ standardavvikelseca 10 %). För svagt instabila förhållanden, räcker det med att anta neutral skiktning iIDM-beräkningarna. Om det är mer instabilt, bör man ta hänsyn till stabiliteten ochäven inkludera en obalansterm. Obalanstermen introduceras implicit genom att varieraden effektiva Kolmogorovkonstanten med stabiliteten. Den effektivaKolmogorovkonstanten som användes här, varierade från 0.5 till över 0.8. För att beräkna u* med hjälp av IDM, beräknades en första uppskattning av u* genom att använda en parametriserad ”drag-coefficient” CD. För att efterlikna demedel man har att tillgå på skepp och bojar i rörelse ute på havet, beräknadesstabilitetsparametern, z/L, med hjälp av ett bulkbestämt värmeflöde. Den storaspridningen av data visade att det är viktigt att parameteriseringen av CD samt värmeflödet är bra. Man kan dra slutsatsen att dissipationsmetoden fungerar tillfredsställande, som metodatt bestämma turbulenta flöden över land. Den större spridningen som man fått överhav är förmodligen en effekt av t.ex. vågor, trots att havsytan anses vara merhomogen och förhållandena mer stationära.
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Jiang, Xiaoyan doctor of geological sciences. "Regional-scale land--climate interactions and their impacts on air quality in a changing climate." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-12-2346.
Повний текст джерелаАнотація:
Land surface areas, which represent approximately 30% of the Earth’s surface, contribute largely to the complexity of the climate system by exchanging water, energy, momentum, and chemical materials with the overlying atmosphere. Because of the highly heterogeneous nature of the land surface and its rapid transformation due to human activities, future climate projections are less certain on regional scales than for the globe as a whole. The work presented in this dissertation is focused on a better understanding of regional-scale land–atmosphere interactions and their impacts on climate and air quality. Specifically, I concentrate my research on three typical regions in the United States (U.S.): 1) the Central U.S. (representing transition zones between arid and wet climates); 2) the Houston metropolitan region (representing a major urban area); and 3) the eastern U.S. (representing temperate forested regions). These regions are also chosen owing to the consideration of data availability.
The first study concerns the roles of vegetation phenology and groundwater dynamics in regulating evapotranspiration and precipitation over the transition zones in summer months. It is found that the warm-season precipitation in the Central U.S. is sensitive to latent heat fluxes controlled by vegetation dynamics. Groundwater enhances the persistence of soil moisture memory from rainy periods to dry periods by transferring water to upper soil layers through capillary forces. Enhancement in soil moisture facilitates vegetation persistence in dry periods, producing more evaporation to the atmosphere and resulting in enhanced precipitation, which then increases soil moisture. The second study compares the impacts of future urbanization and climate change on regional air quality. The results show that the effect of land use change on surface ozone (O3) is comparable to that of climate change, but the details differ across the domain. The third study deals with the formation and distributions of secondary organic aerosols (SOA) — a largely overlooked but potentially important component in the climate system. Under future different climate scenarios, I found that biogenic emissions — an important precursor of SOA — are expected to increase everywhere over the U.S., with the largest increase found in the southeastern U.S. and the northwestern U.S., while changes in SOA do not necessarily follow those in biogenic emissions. Other factors such as partitioning coefficients, atmospheric oxidative capability, primary organic carbon, and anthropogenic emissions also play a role in SOA formation. Direct and indirect impacts from climate change complicate the future SOA formation.text
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Luhunga, P. M. (Philbert Modest). "Atmospheric boundary layer characterizations over Highveld Region South Africa." Diss., 2013. http://hdl.handle.net/2263/24754.
Повний текст джерелаАнотація:
Atmospheric Boundary Layer (ABL) characteristics can be highly complex; the links between spatial and temporal variability of ABL meteorological quantities and existing land use patterns are still poorly understood due to the non-linearity of air-land interaction processes. This study describes the results from Monin Obukhov similarity theory and statistical analysis of meteorological observations collected by a network of ten Automatic Weather Stations (AWSs). The stations were in operation in the Highveld Priority Area (HPA) of the Republic of South Africa during 2008 – 2010. The spatial distribution of stability regimes as presented by both bulk Richardson number (BRN) and Obukhov length (L) indicates that HPA is dominated by strong stability regime. The momentum and heat fluxes show no significant spatial variation between stations. Statistical analysis revealed localization, enhancement and homogenization in the inter-station variability of observed meteorological quantities (temperature, relative humidity and wind speed) over diurnal and seasonal cycles. Enhancement of the meteorological spatial variability was found on a broad range of scales from 20 to 50 km during morning hours and in the dry winter season. These spatial scales are comparable to scales of observed land use heterogeneity, which suggests links between atmospheric variability and land use patterns through excitation of horizontal meso-scale circulations. Convective motions homogenized and synchronized meteorological variability during afternoon hours in the winter seasons, and during large parts of the day during the moist summer season. The analysis also revealed that turbulent convection overwhelms horizontal meso-scale circulations in the study area during extensive parts of the annual cycleDissertation (MSc)--University of Pretoria, 2013.
Geography, Geoinformatics and Meteorology
Unrestricted
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"Participatory Roles of Urban Trees in Regulating Environmental Quality." Doctoral diss., 2019. http://hdl.handle.net/2286/R.I.55524.
Повний текст джерелаАнотація:
abstract: The world has been continuously urbanized and is currently accommodating more than half of the human population. Despite that cities cover only less than 3% of the Earth’s land surface area, they emerged as hotspots of anthropogenic activities. The drastic land use changes, complex three-dimensional urban terrain, and anthropogenic heat emissions alter the transport of mass, heat, and momentum, especially within the urban canopy layer. As a result, cities are confronting numerous environmental challenges such as exacerbated heat stress, frequent air pollution episodes, degraded water quality, increased energy consumption and water use, etc. Green infrastructure, in particular, the use of trees, has been proved as an effective means to improve urban environmental quality in existing research. However, quantitative evaluations of the efficacy of urban trees in regulating air quality and thermal environment are impeded by the limited temporal and spatial scales in field measurements and the deficiency in numerical models.
This dissertation aims to advance the simulation of realistic functions of urban trees in both microscale and mesoscale numerical models, and to systematically evaluate the cooling capacity of urban trees under thermal extremes. A coupled large-eddy simulation–Lagrangian stochastic modeling framework is developed for the complex urban environment and is used to evaluate the impact of urban trees on traffic-emitted pollutants. Results show that the model is robust for capturing the dispersion of urban air pollutants and how strategically implemented urban trees can reduce vehicle-emitted pollution. To evaluate the impact of urban trees on the thermal environment, the radiative shading effect of trees are incorporated into the integrated Weather Research and Forecasting model. The mesoscale model is used to simulate shade trees over the contiguous United States, suggesting how the efficacy of urban trees depends on geographical and climatic conditions. The cooling capacity of urban trees and its response to thermal extremes are then quantified for major metropolitans in the United States based on remotely sensed data. It is found the nonlinear temperature dependence of the cooling capacity remarkably resembles the thermodynamic liquid-water–vapor equilibrium. The findings in this dissertation are informative to evaluating and implementing urban trees, and green infrastructure in large, as an important urban planning strategy to cope with emergent global environmental changes.Dissertation/Thesis
Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2019
Книги з теми "Air-land interaction"
1
C, Winter Thomas, and Likens Gene E. 1935-, eds. Mirror Lake: interactions among air, land, and water. Berkeley, Calif: University of California Press, 2010.
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2
Arellano, Jordi Vilà-Guerau de. Atmospheric boundary layer: Integrating air chemistry and land interactions. New York, NY: Cambridge University Press, 2015.
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3
United States. National Aeronautics and Space Administration., ed. High-frequency variations in earth rotation and the planetary momentum budget: Final report on contract NASW-4731. [Washington, D.C: National Aeronautics and Space Administration, 1995.
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4
United States. National Aeronautics and Space Administration., ed. High-frequency variations in earth rotation and the planetary momentum budget: Final report on contract NASW-4731. [Washington, D.C: National Aeronautics and Space Administration, 1995.
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5
United States. National Aeronautics and Space Administration., ed. High-frequency variations in earth rotation and the planetary momentum budget: Final report on contract NASW-4731. [Washington, D.C: National Aeronautics and Space Administration, 1995.
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6
M, Crill P., Harriss Robert C, and United States. National Aeronautics and Space Administration., eds. Episodic nitrous oxide soil emmissions in Brazilian savanna (cerrado) fire-scars. [Washington, DC]: National Aeronautics and Space Administration, 1994.
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M, Crill Patrick, Harriss Robert C, and United States. National Aeronautics and Space Administration., eds. Episodic nitrous oxide soil emmissions in Brazilian savanna (cerrado) fire-scars. [Washington, DC]: National Aeronautics and Space Administration, 1994.
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8
Labgaa, Rachid R. A model of the CO2 exchanges between biosphere and atmosphere in the tundra. Santa Barbara, CA: Earth-Space Research Group, CRSEO -- Ellison Hall, University of California Santa Barbara, 1994.
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1952-, Clifford Stephen Mark, Haberele Robert M, and Lunar and Planetary Institute, eds. MECA Workshop on Atmospheric H₂O Observations of Earth and Mars: Physical processes, measurements, and interpretations. Houston, Tex: The Institute ; [Springfield, Va., 1988.
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10
L, Crosson William, and United States. National Aeronautics and Space Administration., eds. Regional-scale hydrology with a new land surface processes model. Washington, DC: National Aeronautics and Space Administration, 1995.
Знайти повний текст джерелаЧастини книг з теми "Air-land interaction"
1
Solimini, Domenico. "Wave Interaction with Land, Water and Air." In Remote Sensing and Digital Image Processing, 543–646. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-25633-7_14.
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Likens, Gene E. "The Aquatic Ecosystem and Air-Land-Water Interactions." In An Ecosystem Approach to Aquatic Ecology, 430–35. New York, NY: Springer New York, 1985. http://dx.doi.org/10.1007/978-1-4613-8557-8_8.
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3
Hsu, S. A. "Air–Sea–Land Interaction." In Coastal Meteorology, 140–79. Elsevier, 1988. http://dx.doi.org/10.1016/b978-0-08-050215-1.50010-4.
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Riveiro, Maria. "The Importance of Visualization and Interaction in the Anomaly Detection Process." In Innovative Approaches of Data Visualization and Visual Analytics, 133–50. IGI Global, 2014. http://dx.doi.org/10.4018/978-1-4666-4309-3.ch007.
Повний текст джерелаАнотація:
Large volumes of heterogeneous data from multiple sources need to be analyzed during the surveillance of large sea, air, and land areas. Timely detection and identification of anomalous behavior or any threat activity is an important objective for enabling homeland security. While it is worth acknowledging that many existing mining applications support identification of anomalous behavior, autonomous anomaly detection systems for area surveillance are rarely used in the real world since these capabilities and applications present two critical challenges: they need to provide adequate user support and they need to involve the user in the underlying detection process. Visualization and interaction play a crucial role in providing adequate user support and involving the user in the detection process. Therefore, this chapter elaborates on the role of visualization and interaction in the anomaly detection process, using the surveillance of sea areas as a case study. After providing a brief description of how operators identify conflict traffic situations and anomalies, the anomaly detection problem is characterized from a data mining point of view, suggesting how operators may enhance the process through visualization and interaction.
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Riveiro, Maria. "The Importance of Visualization and Interaction in the Anomaly Detection Process." In Business Intelligence, 880–97. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-4666-9562-7.ch046.
Повний текст джерелаАнотація:
Large volumes of heterogeneous data from multiple sources need to be analyzed during the surveillance of large sea, air, and land areas. Timely detection and identification of anomalous behavior or any threat activity is an important objective for enabling homeland security. While it is worth acknowledging that many existing mining applications support identification of anomalous behavior, autonomous anomaly detection systems for area surveillance are rarely used in the real world since these capabilities and applications present two critical challenges: they need to provide adequate user support and they need to involve the user in the underlying detection process. Visualization and interaction play a crucial role in providing adequate user support and involving the user in the detection process. Therefore, this chapter elaborates on the role of visualization and interaction in the anomaly detection process, using the surveillance of sea areas as a case study. After providing a brief description of how operators identify conflict traffic situations and anomalies, the anomaly detection problem is characterized from a data mining point of view, suggesting how operators may enhance the process through visualization and interaction.
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Eneanya, Augustine Nduka. "Integrating Ecosystem Management and Environmental Media for Public Policy on Public Health and Safety." In Handbook of Research on Environmental Policies for Emergency Management and Public Safety, 321–38. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-3194-4.ch017.
Повний текст джерелаАнотація:
Over the past three decades, the relationship between ecology and public policy has changed because of the increasing role of scientific uncertainty in environmental policy making. While earlier policy questions might have been solved simply by looking at the scientific technicalities of the issues, the increased role of scientific uncertainty in environmental policy making requires that we re-examine the methods used in decision-making. Previously, policymakers use scientific data to support their decision-making disciplinary boundaries are less useful because uncertain environmental policy problems span the natural sciences, engineering, economics, politics, and ethics. The chapter serves as a bridge integrating environmental ecosystem, media, and justice into policy for public health and safety. The chapter attempts to demonstrate the linkage between the environmental policy from a holistic perspective with the interaction of air, water, land, and human on public health and safety.
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Eneanya, Augustine Nduka. "Integrating Ecosystem Management and Environmental Media for Public Policy on Public Health and Safety." In Research Anthology on Public Health Services, Policies, and Education, 612–29. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8960-1.ch028.
Повний текст джерелаАнотація:
Over the past three decades, the relationship between ecology and public policy has changed because of the increasing role of scientific uncertainty in environmental policy making. While earlier policy questions might have been solved simply by looking at the scientific technicalities of the issues, the increased role of scientific uncertainty in environmental policy making requires that we re-examine the methods used in decision-making. Previously, policymakers use scientific data to support their decision-making disciplinary boundaries are less useful because uncertain environmental policy problems span the natural sciences, engineering, economics, politics, and ethics. The chapter serves as a bridge integrating environmental ecosystem, media, and justice into policy for public health and safety. The chapter attempts to demonstrate the linkage between the environmental policy from a holistic perspective with the interaction of air, water, land, and human on public health and safety.
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Greiman, Virginia. "The Winds of Change in World Politics and the Impact on Cyber Stability." In Research Anthology on Artificial Intelligence Applications in Security, 2138–51. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-7705-9.ch093.
Повний текст джерелаАнотація:
One of the greatest geopolitical challenges in the 21st century will be competing for the control of cyberspace, the 5th domain of cyberwarfare after land, sea, air, and space, and the major economic challenge of the time. With the advancement of artificial intelligence, the Internet of Things, autonomous vehicles, and unmanned drones, this challenge becomes even greater. This article explores through empirical evidence the interaction among the three powers that shape cyber intelligence and international security: globalism, regionalism, and nationalism. Recently, world politics has created a sense of urgency concerning the new world order and what that means for cyber security and the domain of cyberspace. With the recent cyberattacks targeting the American political system, the Foreign Ministry of the Czech Republic, the government of Croatia, and the 2017 attacks on the cyber systems operated by the Ukrainian government, there is concern about the stability of global connectedness and the potential for diminution of global boundaries. The concern about global stability raises the question of who controls cyberspace and who is accountable when things go wrong. The aim of the article is to advance a conceptualization for cyber governance frameworks for better control of cyber security by governments, intergovernmental organizations, and the private sector.
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Greiman, Virginia. "The Winds of Change in World Politics and the Impact on Cyber Stability." In Research Anthology on Artificial Intelligence Applications in Security, 2138–51. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-7705-9.ch093.
Повний текст джерелаАнотація:
One of the greatest geopolitical challenges in the 21st century will be competing for the control of cyberspace, the 5th domain of cyberwarfare after land, sea, air, and space, and the major economic challenge of the time. With the advancement of artificial intelligence, the Internet of Things, autonomous vehicles, and unmanned drones, this challenge becomes even greater. This article explores through empirical evidence the interaction among the three powers that shape cyber intelligence and international security: globalism, regionalism, and nationalism. Recently, world politics has created a sense of urgency concerning the new world order and what that means for cyber security and the domain of cyberspace. With the recent cyberattacks targeting the American political system, the Foreign Ministry of the Czech Republic, the government of Croatia, and the 2017 attacks on the cyber systems operated by the Ukrainian government, there is concern about the stability of global connectedness and the potential for diminution of global boundaries. The concern about global stability raises the question of who controls cyberspace and who is accountable when things go wrong. The aim of the article is to advance a conceptualization for cyber governance frameworks for better control of cyber security by governments, intergovernmental organizations, and the private sector.
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Woodward, Jamie. "Editorial Introduction." In The Physical Geography of the Mediterranean. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780199268030.003.0010.
Повний текст джерелаАнотація:
By examining both contemporary processes and long-term records of change, this volume explores the climates, landscapes, ecosystems, and hazards that comprise the Mediterranean world. This is the only region on Earth where three continents meet and their interaction has produced a very distinctive physical geography. This book examines the landscapes and processes at the margins of the three continents and the distinctive marine environment between them. In broad terms, the physical geography of the Mediterranean is a product of long-term interplay between tectonic forces, climate change, river basin and marine processes, and biosphere dynamics, as well as the action of humans during the course of the Holocene. From the outset, it is important to keep in mind that this physical geography is an integration of energy, materials, and processes within a much wider global system. The Mediterranean is a zone of convergence and interaction. It is a meeting place not only for tectonic plates, but also for air masses, energy, and river flows from both temperate and tropical latitudes. The region also interacts directly with the global ocean, receiving cool North Atlantic waters in exchange for the warmer and saltier waters produced in the basins of the Mediterranean Sea. It is also a biodiversity hotspot; the Mediterranean has been a meeting place for plants, animals, and humans from three continents throughout much of its history. The chapters in Part I set out the physical and biological framework for the rest of the book and examine key debates about the evolution of the Mediterranean environment. They explore fundamental interactions between the lithosphere, atmosphere, hydrosphere, and biosphere across a range of spatial and temporal scales. The scene is set for later chapters that focus more closely on particular aspects of the Mediterranean environment such as ecosystem dynamics, river basin systems, karst environments, natural hazards, and land degradation. Chapter 1 examines the role of tectonic processes in the development of the Mediterranean landscape and its marine basins. Also highlighted are the dramatic environmental changes and the geomorphological legacy associated with the Messinian Salinity Crisis of the Late Miocene. Chapter 2 focuses on the marine environment, both ancient and modern.
Тези доповідей конференцій з теми "Air-land interaction"
1
Pfau, A., A. I. Kalfas, and R. S. Abhari. "Making Use of Labyrinth Interaction Flow." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53797.
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It is the aim of this publication to attract the designers attention to the end wall flow interactions of shrouded high pressure turbines. One of the key issue for designing better turbines is the understanding of the flow interactions set up by the presence of labyrinth seals. Those interaction flows are carefully examined in this publication using the control volume analysis and the radial equilibrium of forces acting on streamlines. The consequences on secondary flow development and mixing losses are discussed and quantified. Out of this insight, design recommendations are derived, which attempt to make use of the nature of the labyrinth interaction flow. The open labyrinth cavities are classified in a systematic way. The aim of this approach is to work out the characteristic differences between hub and tip cavities and those having a leakage jet or sucking main flow fluid into the labyrinth. The influence on the main flow is discussed in terms of the incidence flow angle of downstream blade rows and the associated loss production mechanisms. The design strategies presented in this paper follow two paths: (a) Optimization of the mixing losses of the leakage jets at hub and tip is estimated to result in an efficiency increase of up to 0.2%. (b) The non-axisymmetric shaping of the labyrinth interaction flow path aims at the secondary flow control in downstream blade rows. This approach might contribute in the same magnitude of order as reduction in the mixing losses.
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Gorla, Rama S. R., Shantaram S. Pai, and Jeffrey J. Rusick. "Probabilistic Study of Fluid Structure Interaction." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30308.
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A combustor liner was computationally simulated and probabilistically evaluated in view of the several uncertainties in the aerodynamic, structural, material and thermal variables that govern the combustor liner. The interconnection between the computational fluid dynamics code and the finite element structural analysis codes was necessary to couple the thermal profiles with structural design. The stresses and their variations were evaluated at critical points on the liner. Cumulative distribution functions and sensitivity factors were computed for stress responses due to the aerodynamic, mechanical and thermal random variables. It was observed that the inlet and exit temperatures have a lot of influence on the hoop stress. For prescribed values of inlet and exit temperatures, the Reynolds number of the flow, coefficient of thermal expansion, gas emissivity and absorptivity and thermal conductivity of the material have about the same impact on the hoop stress. These results can be used to quickly identify the most critical design variables in order to optimize the design and make it cost effective.
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Shum, Y. K. P., C. S. Tan, and N. A. Cumpsty. "Impeller-Diffuser Interaction in Centrifugal Compressor." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0428.
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A study has been conducted, using an unsteady three-dimensional Reynolds-averaged Navier-Stokes simulation, to define the effect of impeller-diffuser interaction on the performance of a centrifugal compressor stage. The principal finding from the study was that the most influential aspect of this unsteady interaction was the effect on impeller tip leakage flow. In particular, the unsteadiness due to the upstream potential effect of the diffuser vanes led to larger viscous losses associated with the impeller tip leakage flow. The consequent changes at the impeller exit with increasing interaction were identified as reduced slip, reduced blockage, and increased loss. The first two were beneficial to pressure rise while the third one was detrimental. The magnitudes of the effects were examined using different impeller-diffuser spacings and it was shown that there was an optimal radial gap size for maximum impeller pressure rise. The physical mechanism was also determined: when the diffuser was placed closer to the impeller than the optimum, increased loss overcame the benefits of reduced slip and blockage. The findings provide a rigorous explanation for experimental observations made on centrifugal compressors. The success of a simple flow model in capturing the pressure rise trend indicated that although the changes in loss, blockage and slip were due largely to unsteadiness, the consequent impacts on performance were mainly one-dimensional. The influence of flow unsteadiness on diffuser performance was found to be less important than the upstream effect, by a factor of seven in terms of stage pressure rise in the present geometry. It is thus concluded that the beneficial effects of impeller-diffuser interaction on overall stage performance come mainly from the reduced blockage and reduced slip associated with the unsteady tip leakage flow in the impeller.
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Al-Nahwi, Ammar A., James D. Paduano, and Samir A. Nayfeh. "Aerodynamic-Rotordynamic Interaction in Axial Compression Systems: Part II — Impact of Interaction on Overall System Stability." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30489.
Повний текст джерелаАнотація:
This paper presents an integrated treatment of the dynamic coupling between the flow field (aerodynamics) and rotor structural vibration (rotordynamics) in axial compression systems. This work is motivated by documented observations of tip clearance effects on axial compressor flow field stability, the destabilizing effect of fluid-induced aerodynamic forces on rotordynamics, and their potential interaction. This investigation is aimed at identifying the main nondimensional design parameters governing this interaction, and assessing its impact on overall stability of the coupled system. The model developed in this work employs a reduced-order Moore-Greitzer model for the flow field, and a Jeffcott-type model for the rotordynamics. The coupling between the fluid and structural dynamics is captured by incorporating a compressor pressure rise sensitivity to tip clearance, together with a momentum based model for the aerodynamic forces on the rotor (presented in Part I of this paper). The resulting dynamic model suggests that the interaction is largely governed by two nondimensional parameters: the sensitivity of the compressor to tip clearance and the ratio of fluid mass to rotor mass. The aerodynamic-rotordynamic coupling is shown to generally have an adverse effect on system stability. For a supercritical rotor and a typical value of the coupling parameter, the stability margin to the left of the design point is shown to decrease by about 5% in flow coefficient (from 20% for the uncoupled case). Doubling the value of the coupling parameter not only produces a reduction of about 8% in the stability margin at low flow coefficients, but also gives rise to a rotordynamic instability at flow coefficients 7% higher than the design point.
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Van Zante, Dale E., Wai-Ming To, and Jen-Ping Chen. "Blade Row Interaction Effects on the Performance of a Moderately Loaded NASA Transonic Compressor Stage." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30575.
Повний текст джерелаАнотація:
Blade row interaction effects on loss generation in compressors have received increased attention as compressor work-per-stage and blade loading have increased. Two dimensional Laser Doppler Velocimeter measurements of the velocity field in a NASA transonic compressor stage show the magnitude of interactions in the velocity field at the peak efficiency and near stall operating conditions. The experimental data are presented along with an assessment of the velocity field interactions. In the present study the experimental data are used to confirm the fidelity of a three-dimensional, time-accurate, Navier Stokes calculation of the stage using the MSU-TURBO code at the peak efficiency and near stall operating conditions. The simulations are used to quantify the loss generation associated with interaction phenomena. At the design point the stator pressure field has minimal effect of the rotor performance. The rotor wakes do have an impact on loss production in the stator passage at both operating conditions. A method for determining the potential importance of blade row interactions on performance is presented.
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Barter, J. W., P. H. Vitt, and J. P. Chen. "Interaction Effects in a Transonic Turbine Stage." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0376.
Повний текст джерелаАнотація:
A 3D, viscous, time-accurate code has been used to predict the time-dependent flowfield in a transonic turbine stage. Two analytical techniques are used to understand the unsteady physics. One technique takes into account interaction effects associated with reflected waves bouncing between blade rows while the other neglects them. Both techniques model the exact blade counts using phase-lag boundary conditions. The analytical techniques are validated by comparing to unsteady pressure measurements which have been made on the vane and blade surfaces at midspan. The analytical results are then used to understand the importance of interaction effects when the blade rows are close-coupled and when they are more widely spaced. The results show that interaction effects must be taken into account in order to accurately predict the unsteady loading on the upstream blade row. However, for the downstream blade row, interaction effects are second order and do not routinely need to be taken into account in the design process.
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Paradiso, B., G. Persico, P. Gaetani, O. Schennach, R. Pecnik, and J. Woisetschla¨ger. "Blade Row Interaction in a One and a Half Stage Transonic Turbine Focusing on Three Dimensional Effects: Part I—Stator-Rotor Interaction." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50291.
Повний текст джерелаАнотація:
The unsteady and fully three-dimensional aerodynamics of HP turbines represent a relevant research branch for future aero-engine design. When stator-rotor interaction mechanisms and clocking effects are of concern, advanced measurement techniques as well as unsteady CFD codes are required. An extensive study on this topic was carried out in a one and a half stage transonic turbine operating at Graz University of Technology. Two steady and unsteady measurement techniques (Laser Doppler Velocimetry and a Fast Response Aerodynamic Pressure Probe) and an unsteady 3D CFD code were applied to the problem. In this paper, the 1st vane – rotor interaction is presented and discussed in detail to provide the basis for the analysis of the rotor – 2nd vane and the vane-vane interactions. The rotor-exit flowfield is mainly characterized by the wake, the hub passage vortex, the tip leakage vortex and the trailing edge shocks. All the flow structures except the tip leakage flow are strongly influenced by the first vane; in particular the main source of blade row interaction is the first vane trailing edge shock, that periodically alters the rotor trailing edge shock and the rotor hub passage vortex. The comparison with the CFD assesses the interpretation of the flow physics, and supports the identification of the first stator effects at the second stator inlet. A discussion on the stage performance is also provided.
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Liu, Yangwei, Baojie Liu, and Lipeng Lu. "Investigation of Unsteady Impeller-Diffuser Interaction in a Transonic Centrifugal Compressor Stage." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22737.
Повний текст джерелаАнотація:
In this paper, unsteady impeller-diffuser interaction in a transonic centrifugal compressor stage, which is composed of an impeller with splitter blade and a vaned diffuser, was studied numerically. The unsteady interaction has a significant impact on the time-averaged flow, which are presented by the so-called deterministic correlations in the average-passage equation system (APES) proposed by Adamczyk. Both steady and unsteady simulations were carried out at the design and off-design conditions. Results from the steady and unsteady simulations were compared to highlight the importance of the unsteady interactions and to help assess the shortcomings of simple mixing-plane methods. The comparisons indicate that the unsteady interactions should be considered in the simulations since the differences between the time averaged unsteady results and steady simulation results are significant especially at off-design conditions. Then the interactions between impeller and diffuser were studied in detail to advance the understanding of the flow physics involved. The results show that the impeller/diffuser interaction can affect a range of 30% impeller chord from impeller trailing edge on impeller performance, while whole chord length on diffuser performance. The potential effects of the diffuser cause an unsteady pressure disturbance at the impeller exit, leading to the unsteadiness of impeller load, tip leakage flow and losses. While the unsteadiness of impeller exit flow cause period varieties of inlet flow conditions for the diffuser and have large impacts on diffuser performance. Based on the unsteady results, deterministic correlations in the APES framework were computed and analyzed in order to reveal some shortcomings of present deterministic correlations models and to make some contributions to the modeling development. The distribution characteristics of deterministic correlations were studied. The study indicates that the deterministic correlations in the impeller and diffuser have the similar magnitudes, and that the correlations in the passages have large gradients in circumferential direction and decrease rapidly in flow direction especially in the vaneless space. The deterministic correlations at the impeller/diffuser interface were compared with their spatial correlations using the framework of the deterministic decomposition. The comparisons show that the spatial correlations have some discrepancies with the total deterministic correlations at the impeller/diffuser interface.
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Yao, Jixian, and Scott Carson. "HPT/LPT Interaction and Flow Management in the Inter-Turbine Space of a Modern Axial Flow Turbine." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90636.
Повний текст джерелаАнотація:
Understanding the unsteady flows of turbine sub-component interaction has been an important aspect in the design of modern aircraft engines to improve component performance. This research is focused on the inter-turbine space and its neighboring blade rows where intensive interactions of the two turbine sub-components occur. Via large-scale parallel numerical simulations, the paper presents the loss mechanism of the HPT rotor shock-wake interaction, the interaction loss transfer, analysis of the 1st LPT nozzle loading, the performance and flow capacity of the 1st LPT stage. Flow management is performed via a reduced-shock HPT rotor design and a 2-in spacer in the inter-turbine space, aimed at reducing interaction loss and wake ingestion loss by the LPT. The effectiveness of these means is analyzed and comparisons are made to baseline configurations.
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Reddy Gorla, Rama Subba, Shantaram S. Pai, Isaiah Blankson, Srinivas C. Tadepalli, and Sreekantha Reddy Gorla. "Unsteady Fluid Structure Interaction in a Turbine Blade." In ASME Turbo Expo 2005: Power for Land, Sea, and Air. ASMEDC, 2005. http://dx.doi.org/10.1115/gt2005-68157.
Повний текст джерелаАнотація:
An unsteady, three dimensional Navier-Stokes solution in rotating frame formulation for turbomachinery applications has been described. Casting the governing equations in a rotating frame enables the freezing of grid motion and results in substantial savings in computer time. Heat transfer to a gas turbine blade was computationally simulated by finite element methods and probabilistically evaluated in view of the several uncertainties in the performance parameters. The interconnection between the CFD code and finite element structural analysis code was necessary to couple the thermal profiles with the structural design. The stresses and their variations were evaluated at critical points on the turbine blade. Cumulative distribution functions and sensitivity factors were computed for stresses due to the aerodynamic, geometric, material and thermal random variables. These results can be used to quickly identify the most critical design variables in order to optimize the design and make it cost effective. The analysis leads to the selection of the appropriate materials to be used and to the identification of both the most critical measurements and parameters.
Звіти організацій з теми "Air-land interaction"
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Peirson, W. L., T. D. Shand, J. E. Ruprecht, J. Evans, and R. J. Cox. Assessment of the Effects of Air-Sea-Land Interaction Processes on the Intensity and Impact of Modelled and Observed Coastal Extratropical Cyclones. Fort Belvoir, VA: Defense Technical Information Center, September 2011. http://dx.doi.org/10.21236/ada548928.
Повний текст джерела