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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Structure verticale des tourbillons de mésoéchelle dans les quatre grands systèmes d'upwelling de bord est / Vertical structure of mesoscale eddies in the four major eastern boundary upwelling systems

Pegliasco, Cori 02 December 2015 (has links)
Basé sur l'analyse conjointe et complémentaire de ~10 ans de données altimétriques et de profils verticaux de température et de salinité acquis par les profileurs Argo, l'objectif principal de cette thèse est d'étudier en détail les caractéristiques de surface et la structure verticale des tourbillons dans les 4 grands systèmes d'upwelling mondiaux (EBUS Pérou-Chili, Californie, Canaries et Benguela), qui partagent une dynamique à grande échelle relativement similaire. Les résultats principaux montrent que l'ensemble des tourbillons détectés sur les cartes altimétriques dans les 4 EBUS ont des propriétés physiques relativement proches, avec une forte proportion de tourbillons de faibles dimensions ayant une durée de vie relativement courte. Au contraire, la faible partie des tourbillons échantillonnés par les profileurs Argo montre des dimensions bien plus grandes pour des durées de vie plus longues. La sur-représentation de ces grandes échelles dans le jeu des tourbillons échantillonnés par les profileurs Argo est donc le biais majeur des résultats obtenus sur la structure verticale des tourbillons. L'analyse des profils moyens d'anomalies de température et de salinité acquis par les profileurs Argo dans les tourbillons révèle une forte hétérogénéité entre les 4 EBUS, mais également au sein de chacun de ces systèmes d'upwelling. Les structures verticales des tourbillons sont fortement liées à l'hydrologie et à la dynamique locale. Par exemple, les tourbillons de subsurface du PCUS occupent plutôt la partie Sud du système, alors que les tourbillons intensifiés en surface sont présents à la limite Nord de la gyre subtropicale. Dans le CALUS, la présence de Cuddies se devine à la côte, les autres sous-régions contenant des tourbillons dont les anomalies sont majoritairement intensifiées à la base de la pycnocline, avec comme particularité un changement de signe lié à la salinité des couches superficielles. Le CANUS est peuplé de tourbillons très différents en fonction de leur position par rapport à la zone frontale du Cap Vert : au Nord, des tourbillons intenses en subsurface, avec la présence de quelques Meddies ; au Sud, des tourbillons très superficiels. De même dans le BENUS, la partie au Nord de 15°S contient plutôt des tourbillons intensifiés dans les couches de surface, alors qu'au Sud du front d'Angola-Benguela, les tourbillons présentent des anomalies fortes sur une grande partie de la colonne d'eau. L'extrême Sud de cet EBUS est également le lieu de passage des Anneaux des Aiguilles. Les contributions de l'advection isopycnale et du déplacement de la colonne d'eau sur la verticale nous permettent d'affiner la description de ces différentes structures. La présence de grands types de tourbillons, à la morphologie bien distincte (cœur de surface, de subsurface, grande extension verticale, tourbillons fortement intensifiés, etc.), est confirmée par l'étude des tourbillons spécifiquement générés dans la bande côtière. L'analyse Lagrangienne de ces tourbillons nous permet également de décrire l'évolution temporelle de leur structure verticale, qui montre une homogénéité temporelle inattendue. Cette thèse présente donc plusieurs outils facilement applicables dans différentes régions océaniques pour caractériser la structure thermohaline des tourbillons et fournit pour la première fois une description des grands types de tourbillons peuplant les EBUS, soulignant la grande diversité de la mésoéchelle. / Merging ~10 years of altimetry maps and vertical profiles provided by Argo floats, we aim to study in details the eddy's surface characteristics and vertical structure in the 4 major Eastern Boundary Upwelling Systems (EBUS : Peru-Chile, California, Canaries and Benguela), sharing similar large-scale dynamics. Our main results show that the eddies detected on altimetry maps in the 4 EBUS have close physical properties, with a lot of small-scale structures (radius < 40km, amplitude < 1cm and lifetime < 30 days). In contrast, the few eddies sampled by Argo floats have larger dimensions (radius of ~90-140 km, amplitude of ~3-7 cm) and longer lifetimes (6-10 months). The major bias with the analyzed vertical structure is the over representation of these large-scale eddies. The temperature and salinity anomaly mean profiles acquired by Argo floats surfacing within eddies reveals a strong heterogeneity between each of the 4 EBUS, but also within them. The eddies' vertical structure is strongly influence by the local hydrology and dynamics. For example, the subsurface-intensified eddies of the PCUS tend to be located in the Southern part of this EBUS, while the surface-intensified eddies are preferentially located near the Northern boundary of the subtropical gyre. In the CALUS, we can identify Cuddies in some coastal sub-regions, but in this EBUS, most of the eddies are intensified at the base of the pycnocline, with a reversal of the salinity anomaly compared to the surface layers. In the CANUS, the Cape Verde frontal zone separates distinct subsurface-intensified eddies and some Meddies in the North, from the Southern part, where eddies are surface-intensified. In the same way, the Angola-Benguela Front of the BENUS separates the surface-intensified eddies in the North from strong, deep-reaching anomalies in the South. The Southern-most part of the BENUS is also a preferential pathway for the large Agulhas Rings and their associated cyclones. The respective contributions of isopycnal advection and vertical displacement improve the description of these very diverse structures. The presence of several eddy-types, with distinct thermohaline properties (surface or subsurface-intensified, deep vertical extend, intense or not, etc.) is confirmed by the study of eddies generated in the coastal area of each EBUS. Their Lagrangian analysis allows us to describe the temporal evolution of their vertical structure, which shows an unexpected temporal homogeneity. This manuscript presents different efficient tools used to analyze the surface characteristics, the thermohaline properties and the temporal evolution of mesoscale eddies in the 4 major EBUS, highlighting their diversity.
12

Dynamique des blooms phytoplanctoniques dans le gyre subpolaire de l'Atlantique Nord / Phytoplankton blooms dynamics in the North Atlantic Subpolar Gyre

Lacour, Léo 08 December 2016 (has links)
Le gyre subpolaire de l'Atlantique Nord est le siège de la plus importante floraison (bloom) phytoplanctonique de l'océan global. Cet événement biologique majeur joue un rôle crucial sur le fonctionnement des écosystèmes océaniques et sur le cycle global du carbone. L'objectif de cette thèse est de mieux comprendre les processus bio-physiques qui contrôlent la dynamique du bloom phytoplanctonique et l'export de carbone à différentes échelles spatio-temporelles. Dans une première étude, basée sur des données satellites climatologiques, le gyre subpolaire a été biorégionalisé en fonction des différents cycles annuels de biomasse phytoplanctonique. Les conditions de mélange, couplées à l’intensité de la lumière de surface, contrôlent l’initiation du bloom printanier au sein des différentes biorégions. La nouvelle génération de flotteurs BGC-Argo a permis, dans une deuxième étude, d’explorer des processus à des échelles plus fines, en particulier pendant la période hivernale jusqu’à présent très peu étudiée. En hiver, des restratifications intermittentes et locales de la couche de mélange, liées à des processus de sous-mésoéchelle, initient des blooms transitoires qui influencent la dynamique du bloom printanier. Enfin, une troisième étude a montré que la variabilité haute-fréquence de la profondeur de la couche de mélange pendant la transition hiver-printemps joue aussi un rôle crucial sur l’export de carbone. / The North Atlantic Subpolar Gyre exhibits the largest phytoplancton bloom of the global ocean. This major biological event plays a crucial role for the functioning of marine ecosystems and the global carbon cycle. The aim of this thesis is to better understand the bio-physical processes driving the dynamics of the phytoplankton bloom and carbon export at various spatiotemporal scales.In a first study, based on satellite data at a climatological scale, the subpolar gyre is bioregionalized according to distinct annual phytoplankton biomass cycles. The light-mixing regime controls the phytoplankton bloom dynamics in the different bioregions.In a second study, the new generation of BGC-Argo floats allowed for processes to be explored at a finer scale, especially during the overlooked winter season. In winter, intermittent and local restratifications of the mixed layer, triggered by sub-mesoscale processes, initiate transient winter blooms impacting the spring bloom dynamics.Finally, a third study showed how the high-frequency variability of the mixed layer depth during the winter-spring transition plays a crucial role on carbon export.
13

Caracterização da Água Modal Subtropical na região da Confluência Brasil-Malvinas / Subtropical Mode Water characterization in the Brazil-Malvinas Confluence region

Márcio Borges Ferreira 03 March 2017 (has links)
A Confluência Brasil-Malvinas (CBM) é formada pelo encontro da Corrente do Brasil (CB) com a Corrente das Malvinas (CM) no Atlântico Sul e, por constituir o encontro de correntes de contorno oeste (CCO), é demarcada por um intenso gradiente horizontal de temperatura. A inclinação das isopicnais na porção mais quente de regiões de encontro de duas CCO favorece a formação de águas modais ao final do inverno. O estudo de águas modais subtropicais ainda é incipiente no Atlântico Sul, quando comparado com os diversos trabalhos versando sobre o fenômeno em outras regiões do mundo. A realização do primeiro cruzeiro oceanográfico especificamente planejado para o estudo de águas modais na região da CBM e de retroflexão da CB permitiu verificar a anisotropia desse extenso corpo d\'água, cuja espessura e profundidades máxima e mínima variam mormente com a latitude em que o fenômeno ocorre. Os dados fornecidos pelos perfiladores Argo lançados durante o cruzeiro, e ainda em operação na região da CBM, corroboraram tal observação e revelaram o limite norte da região de formação da água modal subtropical do sudoeste do Atlântico Sul (AMSTAS) em torno da latitude de 34°S. A comparação dos resultados obtidos in situ com os dados do modelo oceânico HYCOM, numa simulação de 4 anos, permitiu observar a mesma anisotropia e limite norte da área de formação. Embora relativamente curta, a série temporal viabilizou a primeira estimativa de volume da AMSTAS e uma avaliação preliminar dos processos envolvidos na dissipação da AMSTAS recém formada. O emprego de dados de satélites altímetros para o cálculo do calor armazenado (CA) na região de estudo permitiu verificar que a instabilidade apresentada na série temporal de dados do modelo HYCOM se deve sobretudo à dinâmica de mesoescala na região mais próxima do encontro das duas CCO. A análise do CA na região onde foi realizado o cruzeiro oceanográfico do estudo, permitiu identificar mais claramente a existência de diferentes padrões de calor armazenado coincidentes com áreas típicas de formação, os quais não ocorreram em áreas que continham AMSTAS apenas afundada. / The Brazil-Malvinas confluence zone (BMCZ) is an energetic region of the South Atlantic Ocean where the Brazilian Current (BC) and the Malvinas Current (MC) meet. As a convergence area of Western Boundary Currents (WBC), it is marked by intense horizontal temperature gradients. The inclination of isopycnals in the warm side of WBC convergence zone enables the formation of mode water at the end of winter. The study of subtropical mode waters in the South Atlantic is still incipient compared to similar investigations conducted in other regions of the world. The first oceanographic cruise specifically dedicated to the study of mode waters in the BMCZ and the BC retroflection helped verify the anisotropy of such extensive water masses, whose maximum and minimum thickness and depth vary mainly with the latitude where these phenomenon occur. Data derived from Argo profilers released during the cruise and currently still operating in the BMCZ, support this observation and indicate the northern limit of the formation region of the Southwestern Atlantic subtropical mode water (SASTMW) near latitude 34°S. Comparison of in situ results with those obtained from a 4-years simulation with the HYCOM ocean model, indicates similar anisotropy and northern limit of the formation area. Despite its relatively small length, this time series enabled the first estimation of the SASTMW volume, and a preliminary validation of the processes involved in the dissipation of newly formed SASTMW. The use of satellite altimetry data for the computation of heat content in the study area helped conclude that the instability observed in the time series of the HYCOM model output is due to mesoscale dynamics near the convergence zone of the BC and the MC. Analysis of heat content in the region where the oceanographic cruise was conducted helped identify the existence of different patterns in heat content, that coincide with typical formation areas but not with areas where SASTMW is already submerged.
14

Avaliação da composição modal dinâmica do interior geostrófico dos oceanos / Evaluation of the modal composition of the ocean\'s geostrophic interior

Laurindo, Lucas Cardoso 01 April 2011 (has links)
Este trabalho avalia a importância relativa dosmodos dinâmicos na composição da estrutura vertical do fluxo geostrófico e de suas anomalias em relação à média, com o objetivo de fornecer uma descrição das formas de estratificação predominantes na coluna de água e de identificar prováveis regiões de ocorrência de ondas de Rossby planetárias (OR) dos diversos modos dinâmicos. Raios de deformação internos são estimados para avaliar a possibilidade de interações não-lineares entre OR e as alterações da estratificação local forçadas por sua própria passagem. A análise proposta baseia-se em dados de densidade estimados a partir de perfis verticais de salinidade climatológicos aliados a perfis sintéticos de temperatura. Estes últimos são extrapolados verticalmente a partir de dados orbitais da temperatura da superfície do mar (TSM) e da anomalia da altura da superfície livre (h), segundo um método de reconstrução estatística desenvolvido para este estudo. O primeiro modo baroclínico é dominante tanto no fluxo total quanto em suas anomalias, respondendo em média por 30% da estrutura vertical de velocidade, sendo que este valor descresce aproximadamente por uma razão de três em modos superiores. O segundo modo é significativo ou mesmo dominante em algumas regiões, particularmente em latitudes próximas ao equador. O terceiro é evidente em algumas áreas localizadas, mas não assume papéis importantes em escala de bacia. O modo 0 responde por frações de 6 a 9%, mas é provável que estes resultados sejam subestimados pela metodologia aplicada. Anomalias verticais relacionadas ao primeiro modo coincidem com regiões onde OR longas do primeiro modo tem maior expressão, enquanto o segundo modo parece ser um marcador de OR curtas e ondas de instabilidade tropical. Fenômenos transientes associados ao terceiro modo são observados em áreas restritas dos três oceanos. A magnitude das variações dos raios internos em resposta à fenômenos transientes em algumas regiões implicam em variações significativas na velocidade de fase teórica de OR longas lineares, um indício de que efeitos não-lineares podem ser importantes. Por fim, amplificações da importância do modo barotrópico sobre feições topográficas significativas sugere a existência de mecanismos de transferência de energia entre modos dinâmicos induzidas pela interação com a batimetria. / This study evaluates the relative importance of the dynamical modes in the composition of the geostrophic flow and of its anomalies from the long-term average, respectively seeking to determine the dominant vertical stratification structures of the water column and to identify regions where planetary Rossby waves (RW) of different dynamical modes may most likely occur. The baroclinic Rossby radii of deformation are estimated to evaluate the possibility of nonlinear interactions between RWand changes of the local stratification forced by the wave\'s passing. This analysis is based on density data estimated from climatological salinity profiles and synthetic temperature profiles. The latter are vertically extrapolated for sea surface temperature (SST) and sea surface height anomaly (h) satellite data, using a statistical reconstruction method developed in this study. The first baroclinic mode dominates both the total geostrophic flow and its anomalies, accounting for 30% of the velocity\'s vertical structure on average, where this value decreases approximately by a factor of 3 in subsequent baroclinic orders. The second mode is significant or even dominant in some areas, particularly near the equator. The third mode is evident in some localized regions, but can be ignored at basin-scales. The barotropic mode accounts for 6 to 9% fractions on average, however these values are probably underestimated by the used methods. Vertical anomalies related to the first baroclinic mode coincide with regions where long RWs answers for a significant fraction of local variance, while the second mode highlights zones where short RWs and tropical instability waves are reported. Transient phenomena related with the third mode are observed in comparatively small areas on all three oceans. The magnitude of the baroclinic radii\'s variations in response of the transient variability results in significant changes of the theorethical phase speed for long linear RWs, an evidence that nonlinear effects may be important. Lastly, the greater significance of the barotropic mode over proeminent bottom features suggests the existence of energy transfer mechanisms between dynamical modes triggered by the interaction with the bathymetry.
15

Avaliação da composição modal dinâmica do interior geostrófico dos oceanos / Evaluation of the modal composition of the ocean\'s geostrophic interior

Lucas Cardoso Laurindo 01 April 2011 (has links)
Este trabalho avalia a importância relativa dosmodos dinâmicos na composição da estrutura vertical do fluxo geostrófico e de suas anomalias em relação à média, com o objetivo de fornecer uma descrição das formas de estratificação predominantes na coluna de água e de identificar prováveis regiões de ocorrência de ondas de Rossby planetárias (OR) dos diversos modos dinâmicos. Raios de deformação internos são estimados para avaliar a possibilidade de interações não-lineares entre OR e as alterações da estratificação local forçadas por sua própria passagem. A análise proposta baseia-se em dados de densidade estimados a partir de perfis verticais de salinidade climatológicos aliados a perfis sintéticos de temperatura. Estes últimos são extrapolados verticalmente a partir de dados orbitais da temperatura da superfície do mar (TSM) e da anomalia da altura da superfície livre (h), segundo um método de reconstrução estatística desenvolvido para este estudo. O primeiro modo baroclínico é dominante tanto no fluxo total quanto em suas anomalias, respondendo em média por 30% da estrutura vertical de velocidade, sendo que este valor descresce aproximadamente por uma razão de três em modos superiores. O segundo modo é significativo ou mesmo dominante em algumas regiões, particularmente em latitudes próximas ao equador. O terceiro é evidente em algumas áreas localizadas, mas não assume papéis importantes em escala de bacia. O modo 0 responde por frações de 6 a 9%, mas é provável que estes resultados sejam subestimados pela metodologia aplicada. Anomalias verticais relacionadas ao primeiro modo coincidem com regiões onde OR longas do primeiro modo tem maior expressão, enquanto o segundo modo parece ser um marcador de OR curtas e ondas de instabilidade tropical. Fenômenos transientes associados ao terceiro modo são observados em áreas restritas dos três oceanos. A magnitude das variações dos raios internos em resposta à fenômenos transientes em algumas regiões implicam em variações significativas na velocidade de fase teórica de OR longas lineares, um indício de que efeitos não-lineares podem ser importantes. Por fim, amplificações da importância do modo barotrópico sobre feições topográficas significativas sugere a existência de mecanismos de transferência de energia entre modos dinâmicos induzidas pela interação com a batimetria. / This study evaluates the relative importance of the dynamical modes in the composition of the geostrophic flow and of its anomalies from the long-term average, respectively seeking to determine the dominant vertical stratification structures of the water column and to identify regions where planetary Rossby waves (RW) of different dynamical modes may most likely occur. The baroclinic Rossby radii of deformation are estimated to evaluate the possibility of nonlinear interactions between RWand changes of the local stratification forced by the wave\'s passing. This analysis is based on density data estimated from climatological salinity profiles and synthetic temperature profiles. The latter are vertically extrapolated for sea surface temperature (SST) and sea surface height anomaly (h) satellite data, using a statistical reconstruction method developed in this study. The first baroclinic mode dominates both the total geostrophic flow and its anomalies, accounting for 30% of the velocity\'s vertical structure on average, where this value decreases approximately by a factor of 3 in subsequent baroclinic orders. The second mode is significant or even dominant in some areas, particularly near the equator. The third mode is evident in some localized regions, but can be ignored at basin-scales. The barotropic mode accounts for 6 to 9% fractions on average, however these values are probably underestimated by the used methods. Vertical anomalies related to the first baroclinic mode coincide with regions where long RWs answers for a significant fraction of local variance, while the second mode highlights zones where short RWs and tropical instability waves are reported. Transient phenomena related with the third mode are observed in comparatively small areas on all three oceans. The magnitude of the baroclinic radii\'s variations in response of the transient variability results in significant changes of the theorethical phase speed for long linear RWs, an evidence that nonlinear effects may be important. Lastly, the greater significance of the barotropic mode over proeminent bottom features suggests the existence of energy transfer mechanisms between dynamical modes triggered by the interaction with the bathymetry.
16

Structure de la stratification dans les gyres subtropicaux et sa variabilité décennale dans l'océan Atlantique Nord / Stratification structure in subtropical gyres and its decadal variability in the North Atlantic Ocean

Feucher, Charlène 21 November 2016 (has links)
Les gyres subtropicaux sont au coeur des changements observés au cours des dernières décennies. On y observe entre la surface et la pycnocline permanente une augmentation du contenu thermique de l’océan. La pycnocline permanente délimite un important réservoir de chaleur et joue un rôle majeur en empêchant la chaleur accumulée en surface d’atteindre les profondeurs de l’océan. La pycnocline permanente est donc d’un intérêt important dans un contexte de changement climatique. Pour la première fois et grâce au réseau de données Argo, nous avons été capables de déterminer les propriétés de la pycnocline permanente. L’objectif de cette thèse est de déterminer la structure de la pycnocline permanente et d’étudier sa variabilité au cours des dernières décennies. Une méthode de détermination objective de la pycnocline permanente a été développée. Cette méthode a d’abord été appliquée à l’océan Atlantique nord avec les données Argo puis à l’océan global. Une structure complexe de la pycnocline permanente a été mise en évidence avec de fortes différences d’un gyre à l’autre. La pycnocline permanente est la plus profonde et la plus épaisse dans le gyre subtropical nord Atlantique. Cela explique que le gyre subtropical nord Atlantique soit le plus grand réservoir de chaleur au monde. Ensuite, les relations entre la variabilité du contenu de chaleur et les propriétés de la pycnocline permanente ont été étudiées en s’appuyant sur des réanalyses océaniques. Au cours des dernières décennies, un réchauffement important de l’océan a été observé et particulièrement dans l’océan Atlantique nord. Ce réchauffement est principalement dominé par un approfondissement des isopycnes. Les déplacements verticaux des isopycnes induisent des changements dans la stratification et affectent les propriétés de la pycnocline permanente (profondeur et densité potentielle). / Subtropical gyres are central to the observed climate changes throughout the last decades. It is observed between the surface and the permanent pycnocline an intense increase in the ocean heat content. The permanent pycnocline delineates thus an important heat reservoir. The permanent pycnocline has a major role in preventing heat to reach the deep ocean and it thus of a relative importance in the context of climate change. For the first time and thanks to the development of the Argo array, we have been able to characterize the observed structure of the permanent pycnocline. The objective of this PhD thesis is to investigate the structure of the permanent pycnocline and its variability over the last decades. We developed an objective method to characterize the properties of the permanent pycnocline. This method has been first applied to the North Atlantic Ocean with Argo data and then to the global ocean. A complex structure of the permanent pycnocline emerges with strong differences from one gyre to another. The permanent pycnocline is found to be the deepest and the thickest in the North Atlantic subtropical gyre. It implies that the North Atlantic subtropical gyre is the largest heat reservoir on Earth. Then, ocean reanalyses have been used to investigate the changes in the permanent pycnocline properties in the North Atlantic subtropical gyre. Over the last decades, there is a strong warming of the upper ocean, especially in the North Atlantic subtropical gyre. The warming in the ocean is dominated by the heaving of isopycnal surfaces. This heaving strongly affects the depths of isopycnals and the stratification. This in turn affects the properties of the permanent pycnocline, especially its depth and potential density.
17

Observation de la convection profonde en mer d'Irminger sur la période 2002-2015 par les flotteurs Argo / Observation of Irminger sea deep convection by Argo floats during the 2002-2015 period

Piron, Anne 12 November 2015 (has links)
Les évènements de convection profonde sont importants car ils forment les masses d'eau intermédiaires et profondes qui nourrissent la circulation globale. La mer du Labrador, qui forme la Labrador Sea Water (LSW), est le site le plus documenté de l'océan Atlantique Nord. La mer d'lrminger a également été citée mais n'est pas entièrement reconnue à cause du manque d'observations directes. Cette thèse fournit la première description de la convection profonde en mer d'lrminger à l'échelle du bassin grâce aux données Argo. Trois évènements de convection se sont produits en mer d'lrminger depuis 2010. Au cours de l'hiver 2O11-2O12, la convection atteint 1000 m et est expliquée par la séquence d'apparition des tip jets groenlandais.La convection de l'hiver 2O13-2O14, qui atteint 1300 m, est caractérisée par un préconditionnement particulièrement important et un forçage par les tip jets faible. La convection de l'hiver 2O14-2O15, qui atteint 1700 m, montre des tip jets très nombreux et persistants. L'advection de LSW provenant de la mer du Labrador explique les profondeurs exceptionnelles observées au cours de ces deux derniers hivers. Les résultats montrent que la convection n'est pas rare en mer d'lrminger et qu'elle joue un rôle non négligeable sur l'équilibre climatique. / The deep convection events are important because they form the intermediate and deep water masses feeding the global circulation. The Labrador Sea is the main site of deep convection in the North Atlantic Ocean and produces the intermediate Labrador Sea Water (LSW). The lrminger Sea was also cited but was forgotten during decades because of the lack of direct observations. This thesis provides the first description of the lrminger Sea deep convection at basin scale, thanks to the Argo data. Three convective events occurred in the lrminger Sea since 2010. During the 2011-2012 winter, the convection reached 1000 m and is explained by the sequence of the Greenland tip jets. The event of the 2O13-2O14 winter, reaching 130O m, is characterized by a strong preconditioning and a weak forcings by the Greenland tip jets.The convection event of the 2O14-2015 winter, reaching 1700 m, shows many of persistant tip jets. The advection of LSW from the Labrador Sea explains the deepest mixed layers observed during the last two winters. The results show that deep convection in the lrminger Sea is not a rare isolated event and plays a significant role on the climate balance.
18

Edice literature for young adult v českých nakladatelstvích (Argo, Cooboo, Knižní klub) / Edition of literature for young adult in the Czech publishing houses

Korytářová, Eva January 2017 (has links)
This diploma thesis deals with the current position of young adult literature it the Czech book market. Young adult literature is primarily intended for teenage readers and captures topics that are close to this age group. The aim of the thesis is to find out, how is this kind of literature published in Czech media system. This text also acquaint closer with the term the young adult literature. For this reason, the first part of the work deals with the definition of young adult literature and the presentation of common genres, as well as the brief history and its influence on adolescents. Through interviews with the representatives from the three selected publishers that publish the young adult titles, we have found out which place this literary sector occupies in the Czech book market. The main achievement we have learned is the fact that although the young adult is a relatively new term for the Czech environment, even in the few years that we have encountered, it has become a relatively well-established concept. Young people choose titles with lighter motives, but books that solve more demanding themes are often searched by readers in the long term for several years after their release. Even though the number of Czech young adult titles is still increasing, it is often translated literature....
19

Analýza marketingových nástrojů knižního nakladatelství / Analysis of Book Publisher's Marketing Tools

Gruberová, Laura January 2016 (has links)
This Master's thesis entitled Analysis of Book Publisher's Marketing Tools focuses on the Czech book market and marketing tools that are currently used by book publishers. The aim of the work is to evaluate marketing tools of the specific Czech book publisher based on qualitative research and suggest possible improvements in their use. The theoretical part contains definitions of basic concepts in the field of book publishing and book marketing, which serves as the basis for the practical part. The practical part deals with the analysis of marketing tools of book publisher Argo, presents pros and cons of these instruments and in the end, brings suggestions for their improvement. This part of the thesis is based on marketing situation analysis, on analysis of available data on publisher's activities and on an interview with one of its writers. This thesis is primarily valuable for book publishers and sellers, who can obtain information about possible marketing tools. For book readers, this thesis is particularly interesting in terms of obtaining information about how marketing tools can help them in the selection of books.
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Machine Learning for Improvement of Ocean Data Resolution for Weather Forecasting and Climatological Research

Huda, Md Nurul 18 October 2023 (has links)
Severe weather events like hurricanes and tornadoes pose major risks globally, underscoring the critical need for accurate forecasts to mitigate impacts. While advanced computational capabilities and climate models have improved predictions, lack of high-resolution initial conditions still limits forecast accuracy. The Atlantic's "Hurricane Alley" region sees most storms arise, thus needing robust in-situ ocean data plus atmospheric profiles to enable precise hurricane tracking and intensity forecasts. Examining satellite datasets reveals radio occultation (RO) provides the most accurate 5-25 km altitude atmospheric measurements. However, below 5 km accuracy remains insufficient over oceans versus land areas. Some recent benchmark study e.g. Patil Iiyama (2022), and Wei Guan (2022) in their work proposed the use of deep learning models for sea surface temperature (SST) prediction in the Tohoku region with very low errors ranging from 0.35°C to 0.75°C and the root-mean-square error increases from 0.27°C to 0.53°C over the over the China seas respectively. The approach we have developed remains unparalleled in its domain as of this date. This research is divided into two parts and aims to develop a data driven satellite-informed machine learning system to combine high-quality but sparse in-situ ocean data with more readily available low-quality satellite data. In the first part of the work, a novel data-driven satellite-informed machine learning algorithm was implemented that combines High-Quality/Low-Coverage in-situ point ocean data (e.g. ARGO Floats) and Low-Quality/High-Coverage Satellite ocean Data (e.g. HYCOM, MODIS-Aqua, G-COM) and generated high resolution data with a RMSE of 0.58◦C over the Atlantic Ocean.The second part of the work a novel GNN algorithm was implemented on the Gulf of Mexico and showed it can successfully capture the complex interactions between the ocean and mimic the path of a ARGO floats with a RMSE of 1.40◦C. / Doctor of Philosophy / Severe storms like hurricanes and tornadoes are a major threat around the world. Accurate weather forecasts can help reduce their impacts. While climate models have improved predictions, lacking detailed initial conditions still limits forecast accuracy. The Atlantic's "Hurricane Alley" sees many storms form, needing good ocean and atmospheric data for precise hurricane tracking and strength forecasts. Studying satellite data shows radio occultation provides the most accurate 5-25 km high altitude measurements over oceans. But below 5 km accuracy remains insufficient versus over land. Recent research proposed using deep learning models for sea surface temperature prediction with low errors. Our approach remains unmatched in this area currently. This research has two parts. First, we developed a satellite-informed machine learning system combining limited high-quality ocean data with more available low-quality satellite data. This generated high resolution Atlantic Ocean data with an error of 0.58°C. Second, we implemented a new algorithm on the Gulf of Mexico, successfully modeling complex ocean interactions and hurricane paths with an error of 1.40°C. Overall, this research advances hurricane forecasting by combining different data sources through innovative machine learning techniques. More accurate predictions can help better prepare communities in hurricane-prone regions.

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