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Статті в журналах з теми "Relative Sea-Level Variations":
1
de Boer, B., P. Stocchi, and R. S. W. van de Wal. "A fully coupled 3-D ice-sheet – sea-level model: algorithm and applications." Geoscientific Model Development Discussions 7, no. 3 (May 23, 2014): 3505–44. http://dx.doi.org/10.5194/gmdd-7-3505-2014.
Анотація:
Abstract. Relative sea-level variations during the late Pleistocene cannot be reconstructed regardless of the estimates of ice-volume fluctuations. For the latter, however, the knowledge of regional and global relative sea-level variations is necessary. Overcoming this problem of circularity demands a fully coupled system where ice sheets and sea level vary consistently in space and time and dynamically affect each other. Here we present results for the past 410 000 years (410 kyr) from the coupling of a set of 3-D ice-sheet-shelf models to a global sea-level model based on the solution of gravitationally self-consistent sea-level equation. The sea-level model incorporates all the Glacial Isostatic Adjustment feedbacks for a Maxwell viscoelastic and rotating Earth model with variable coastlines. Ice volume is computed with four 3-D ice-sheet-shelf models for North America, Eurasia, Greenland and Antarctica. With an inverse approach, ice volume and temperature are derived from a benthic δ18O stacked record. The ice-sheet thickness variations are then forwarded to the sea-level model to compute the bedrock deformation, the geoid and the relative sea-level change. The latter are used to generate the new topographies for the next time step, which are forwarded to the ice-sheet models. To quantify the impact of relative sea-level variations on ice-volume evolution, we have performed coupled and uncoupled simulations. The largest differences of ice-sheet thickness change show up in the proximity of the ice-sheets edges, where relative sea-level change significantly departs from the ocean-averaged sea level variation.
2
Nakada, M., and K. Lambeck. "Glacial rebound and relative sea-level variations: a new appraisal." Geophysical Journal International 90, no. 1 (July 1, 1987): 171–224. http://dx.doi.org/10.1111/j.1365-246x.1987.tb00680.x.
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de Boer, B., P. Stocchi, and R. S. W. van de Wal. "A fully coupled 3-D ice-sheet–sea-level model: algorithm and applications." Geoscientific Model Development 7, no. 5 (September 23, 2014): 2141–56. http://dx.doi.org/10.5194/gmd-7-2141-2014.
Анотація:
Abstract. Relative sea-level variations during the late Pleistocene can only be reconstructed with the knowledge of ice-sheet history. On the other hand, the knowledge of regional and global relative sea-level variations is necessary to learn about the changes in ice volume. Overcoming this problem of circularity demands a fully coupled system where ice sheets and sea level vary consistently in space and time and dynamically affect each other. Here we present results for the past 410 000 years (410 kyr) from the coupling of a set of 3-D ice-sheet-shelf models to a global sea-level model, which is based on the solution of the gravitationally self-consistent sea-level equation. The sea-level model incorporates the glacial isostatic adjustment feedbacks for a Maxwell viscoelastic and rotating Earth model with coastal migration. Ice volume is computed with four 3-D ice-sheet-shelf models for North America, Eurasia, Greenland and Antarctica. Using an inverse approach, ice volume and temperature are derived from a benthic δ18O stacked record. The derived surface-air temperature anomaly is added to the present-day climatology to simulate glacial–interglacial changes in temperature and hence ice volume. The ice-sheet thickness variations are then forwarded to the sea-level model to compute the bedrock deformation, the change in sea-surface height and thus the relative sea-level change. The latter is then forwarded to the ice-sheet models. To quantify the impact of relative sea-level variations on ice-volume evolution, we have performed coupled and uncoupled simulations. The largest differences of ice-sheet thickness change occur at the edges of the ice sheets, where relative sea-level change significantly departs from the ocean-averaged sea-level variations.
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Oelsmann, Julius, Marta Marcos, Marcello Passaro, Laura Sanchez, Denise Dettmering, Sönke Dangendorf, and Florian Seitz. "Regional variations in relative sea-level changes influenced by nonlinear vertical land motion." Nature Geoscience 17, no. 2 (February 2024): 137–44. http://dx.doi.org/10.1038/s41561-023-01357-2.
Анотація:
AbstractVertical land movements can cause regional relative sea-level changes to differ substantially from climate-driven absolute sea-level changes. Whereas absolute sea level has been accurately monitored by satellite altimetry since 1992, there are limited observations of vertical land motion. Vertical land motion is generally modelled as a linear process, despite some evidence of nonlinear motion associated with tectonic activity, changes in surface loading or groundwater extraction. As a result, the temporal evolution of vertical land motion, and its contribution to projected sea-level rise and its uncertainty, remains unresolved. Here we generate a probabilistic vertical land motion reconstruction from 1995 to 2020 to determine the impact of regional-scale and nonlinear vertical land motion on relative sea-level projections up to 2150. We show that regional variations in projected coastal sea-level changes are equally influenced by vertical land motion and climate-driven processes, with vertical land motion driving relative sea-level changes of up to 50 cm by 2150. Accounting for nonlinear vertical land motion increases the uncertainty in projections by up to 1 m on a regional scale. Our results highlight the uncertainty in future coastal impacts and demonstrate the importance of including nonlinear vertical land motions in sea-level change projections.
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Novita, Eva, Masita Dwi Mandini Manessa, and Mufti Petala Patria. "Relative and Absolute Sea Level Change Variability in The Palabuhanratu Bay Waters." IOP Conference Series: Earth and Environmental Science 1275, no. 1 (November 1, 2023): 012015. http://dx.doi.org/10.1088/1755-1315/1275/1/012015.
Анотація:
Abstract SLR could affect the waters of Palabuhanratu Bay, which are exposed to the Indian Ocean. Sea levels are rising due to RSL and ASL changes. RSL has increased by 22.86 mm/year based on tidal data for 2013–2022. In contrast, ASL has increased by 4.48 mm/year based on satellite altimetry data for 1992–2022. The research uses the linear regression method to get the SLR value. According to earlier studies, dynamic change elements connected to alterations in the atmosphere and ocean circulation are typically considered when analyzing sea level variations. This work explores sea-level variations, including dynamic and static changes impacted by geological processes like deformation. Dynamic change factors, such as climate anomalies, ENSO, and IOD, affect these changes. Regarding RSL changes, ENSO has a more decisive influence than IOD, and vice versa for ASL changes. In the La Nina phenomenon and negative IOD phase, RSL and ASL trend changes are enhanced, whereas they are lowered in the El Nino and positive IOD phases. These waters’ sea-level variations are only slightly impacted by local processes, such as VLM. It has a more decisive influence on RSL changes than ASL.
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Sultan, S. A. R., F. Ahmad, and D. Nassar. "Relative Contribution of External Sources of Mean Sea-level Variations at Port Sudan, Red Sea." Estuarine, Coastal and Shelf Science 42, no. 1 (January 1996): 19–30. http://dx.doi.org/10.1006/ecss.1996.0002.
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Mitrovica, J. X., and W. R. Peltier. "Constraints on mantle viscosity from relative sea level variations in Hudson Bay." Geophysical Research Letters 19, no. 12 (June 19, 1992): 1185–88. http://dx.doi.org/10.1029/92gl01285.
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Pereira, Elizabeth Santos, Jhone Araújo, Kátia Mansur, Kita Macario, Eduardo Q. Alves, and Fábio Ferreira Dias. "Variations in relative sea level in south America, Brazil: A comprehensive analysis." Quaternary Science Advances 12 (October 2023): 100116. http://dx.doi.org/10.1016/j.qsa.2023.100116.
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Zanchettin, Davide, Sara Bruni, Fabio Raicich, Piero Lionello, Fanny Adloff, Alexey Androsov, Fabrizio Antonioli, et al. "Sea-level rise in Venice: historic and future trends (review article)." Natural Hazards and Earth System Sciences 21, no. 8 (September 1, 2021): 2643–78. http://dx.doi.org/10.5194/nhess-21-2643-2021.
Анотація:
Abstract. The city of Venice and the surrounding lagoonal ecosystem are highly vulnerable to variations in relative sea level. In the past ∼150 years, this was characterized by an average rate of relative sea-level rise of about 2.5 mm/year resulting from the combined contributions of vertical land movement and sea-level rise. This literature review reassesses and synthesizes the progress achieved in quantification, understanding and prediction of the individual contributions to local relative sea level, with a focus on the most recent studies. Subsidence contributed to about half of the historical relative sea-level rise in Venice. The current best estimate of the average rate of sea-level rise during the observational period from 1872 to 2019 based on tide-gauge data after removal of subsidence effects is 1.23 ± 0.13 mm/year. A higher – but more uncertain – rate of sea-level rise is observed for more recent years. Between 1993 and 2019, an average change of about +2.76 ± 1.75 mm/year is estimated from tide-gauge data after removal of subsidence. Unfortunately, satellite altimetry does not provide reliable sea-level data within the Venice Lagoon. Local sea-level changes in Venice closely depend on sea-level variations in the Adriatic Sea, which in turn are linked to sea-level variations in the Mediterranean Sea. Water mass exchange through the Strait of Gibraltar and its drivers currently constitute a source of substantial uncertainty for estimating future deviations of the Mediterranean mean sea-level trend from the global-mean value. Regional atmospheric and oceanic processes will likely contribute significant interannual and interdecadal future variability in Venetian sea level with a magnitude comparable to that observed in the past. On the basis of regional projections of sea-level rise and an understanding of the local and regional processes affecting relative sea-level trends in Venice, the likely range of atmospherically corrected relative sea-level rise in Venice by 2100 ranges between 32 and 62 cm for the RCP2.6 scenario and between 58 and 110 cm for the RCP8.5 scenario, respectively. A plausible but unlikely high-end scenario linked to strong ice-sheet melting yields about 180 cm of relative sea-level rise in Venice by 2100. Projections of human-induced vertical land motions are currently not available, but historical evidence demonstrates that they have the potential to produce a significant contribution to the relative sea-level rise in Venice, exacerbating the hazard posed by climatically induced sea-level changes.
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Bills, Bruce G., and Thomas S. James. "Late Quaternary variations in relative sea level due to glacial cycle polar wander." Geophysical Research Letters 23, no. 21 (October 15, 1996): 3023–26. http://dx.doi.org/10.1029/96gl02886.
Дисертації з теми "Relative Sea-Level Variations":
1
Withnell, Anthony James. "Relative sea-level variations revealed by tide-gauge records of long duration." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/58421.
Анотація:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.Includes bibliographical references (leaves 65-67).
by Anthony James Withnell.
M.S.
2
Kulaiappan, Palanisamy Hindumathi. "Le niveau de la mer actuel : variations globales et régionales." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30166/document.
Анотація:
Le niveau de la mer est une des variables climatiques essentielles dont la variabilité résulte de nombreuses interactions complexes entre toutes les composantes du système climatique sur une large gamme d'échelles spatiales et temporelles. Au cours du XXème siècle, les mesures marégraphiques ont permis d'estimer la hausse du niveau de la mer global entre 1,6 mm/an et 1,8 mm/an. Depuis 1993, les observations faites par les satellites altimétriques indiquent une hausse du niveau de la mer plus rapide de 3,3 mm/an. Grâce à leur couverture quasi-globale, elles révèlent aussi une forte variabilité du niveau de la mer à l'échelle régionale, parfois plusieurs fois supérieure à la moyenne globale du niveau de la mer. Compte tenu de l'impact très négatif de l'augmentation du niveau de la mer pour la société, sa surveillance, la compréhension de ses causes ainsi que sa prévision sont désormais considérées comme des priorités scientifiques et sociétales majeures. Dans cette thèse, nous validons d'abord les variations du niveau de la mer mesurées par la nouvelle mission d'altimétrie satellitaire, SARAL-AltiKa, en comparant les mesures avec celles de Jason- 2 et des marégraphes. Un autre volet de cette première partie de thèse a consisté à estimer les parts respectives des facteurs responsables des variations du niveau de la mer depuis 2003 en utilisant des observations issues de l'altimétrie satellitaire (missions altimétrique Jason-1, Jason-2 et Envisat), de la mission GRACE, et des profils de température et salinité de l'océan par les flotteurs Argo. Une attention particulière est portée à la contribution de l'océan profond non 'vue' par Argo. Nous montrons que les incertitudes dues aux approches du traitement des données et aux erreurs systématiques des différents systèmes d'observation nous empêchent encore d'obtenir des résultats précis sur cette contribution. Dans la deuxième partie de la thèse, en utilisant les données de reconstruction du niveau de la mer dans le passé, nous étudions la variabilité régionale du niveau de la mer et estimons sa hausse totale (composante régionale plus moyenne globale) de 1950 à 2009 dans trois régions vulnérables: l'océan Indien, la mer de Chine méridionale et la mer des Caraïbes. Pour les sites où l'on dispose de mesures du mouvement de la croûte terrestre par GPS, nous évaluons la hausse locale du niveau de la mer relatif (hausse du niveau de la mer totale plus mouvement de la croûte locale) depuis 1950. En comparant les résultats de ces trois régions avec une étude précédente sur le Pacifique tropical, nous constatons que le Pacifique tropical présente la plus forte amplitude des variations du niveau de la mer sur la période d'étude. Dans la dernière partie de la thèse, nous nous concentrons par conséquent sur le Pacifique tropical. Nous analysons les rôles respectifs de la dynamique océanique, des modes de variabilité interne du climat et du forçage anthropique sur les structures de la variabilité régionale du niveau de la mer du Pacifique tropical depuis 1993. Nous montrons qu'une partie importante de la variabilité régionale du niveau de la mer du Pacifique tropical peut être expliquée par le mouvement vertical de la thermocline en réponse à l'action du vent. En tentant de séparer le signal correspondant au mode de variabilité interne du climat de celui de la hausse régionale du niveau de la mer dans le Pacifique tropical, nous montrons également que le signal résiduel restant (c'est-à-dire le signal total moins le signal de variabilité interne) ne correspond probablement pas à l'empreinte externe du forçage anthropiqueSea level is an integrated climate parameter that involves interactions of all components of the climate system (oceans, ice sheets, glaciers, atmosphere, and land water reservoirs) on a wide range of spatial and temporal scales. Over the 20th century, tide gauge records indicate a rise in global sea level between 1.6mm/yr and 1.8 mm/yr. Since 1993, sea level variations have been measured precisely by satellite altimetry. They indicate a faster sea level rise of 3.3 mm/yr over 1993-2015. Owing to their global coverage, they also reveal a strong regional sea level variability that sometimes is several times greater than the global mean sea level rise. Considering the highly negative impact of sea level rise for society, monitoring sea level change and understanding its causes are henceforth high priorities. In this thesis, we first validate the sea level variations measured by the new satellite altimetry mission, SARAL-AltiKa by comparing the measurements with Jason-2 and tide gauge records. We then attempt to close the global mean sea level budget since 2003 and estimate the deep ocean contribution by making use of observational data from satellite altimetry, Argo profiles and GRACE mission. We show that uncertainties due to data processing approaches and systematic errors of different observing systems still prevent us from obtaining accurate results. In the second part of the thesis, by making use of past sea level reconstruction, we study the patterns of the regional sea level variability and estimate climate related (global mean plus regional component) sea level change over 1950-2009 at three vulnerable regions: Indian Ocean, South China and Caribbean Sea. For the sites where vertical crustal motion monitoring is available, we compute the total relative sea level (i.e. total sea level rise plus the local vertical crustal motion) since 1950. On comparing the results from these three regions with already existing results in tropical Pacific, we find that tropical Pacific displays the highest magnitude of sea level variations. In the last part of the thesis, we therefore focus on the tropical Pacific and analyze the respective roles of ocean dynamic processes, internal climate modes and external anthropogenic forcing on tropical Pacific sea level spatial trend patterns since 1993. Building up on the relationship between thermocline and sea level in the tropical region, we show that most of the observed sea level spatial trend pattern in the tropical Pacific can be explained by the wind driven vertical thermocline movement. By performing detection and attribution study on sea level spatial trend patterns in the tropical Pacific and attempting to eliminate signal corresponding to the main internal climate mode, we further show that the remaining residual sea level trend pattern does not correspond to externally forced anthropogenic sea level signal. In addition, we also suggest that satellite altimetry measurement may not still be accurate enough to detect the anthropogenic signal in the 20 year tropical Pacific sea level trends
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Arhan, Damien. "Dynamiques des lignes de rivage et occupation humaine dans l'émirat d'Abu Dhabi à l'Holocène." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUL114.
Анотація:
Les littoraux d’Abu Dhabi, et plus largement ceux du golfe Arabique, ont joué un rôle majeur dans le développement des populations humaines au cours de l’Holocène. Parallèlement, ces milieux apparaissent également comme des espaces très vulnérables. En plus d’être soumis aux variations climatiques régionales, ils ont été fortement exposés aux mobilités des lignes de rivage, contrôlées en partie par les variations du niveau marin. L’étude de ces fluctuations s’avère ainsi essentielle pour reconstituer les évolutions paléogéographiques des littoraux dont dépendaient les sociétés. La thèse présente une synthèse de ces variations et des changements paléoenvironnementaux associés, soutenue par l’apport de nouveaux résultats issus d’un travail de terrain, par l’examen des recherches déjà publiées et par un travail de modélisation reposant sur la création de Sea-Level Index Points, à Abu Dhabi mais aussi sur l’ensemble de la rive sud du Golfe. Selon une approche géoarchéologique, l’étude cherche simultanément à replacer les sites dans leurs contextes paléoenvironnementaux. En dépit de variations métriquement réduites, les résultats indiquent des impacts considérables sur la morphologie des littoraux, marqués par de très faibles élévations. Ils permettent également d’expliquer en partie la répartition des sites archéologiques. Enfin, ils attestent de l’existence de variations relatives du niveau marin, résultant de dynamiques de surrection et de subsidence des masses terrestres. Les trajectoires identifiées traduisent de fortes disparités régionales et mettent en lumière la complexité et l’imbrication des mécanismes isostatiques, néotectoniques et diapiriquesThe coastlines of Abu Dhabi, and more broadly, those of the Arabian Gulf, have played a major role in the development of human populations during the Holocene. At the same time, these environments appear to be highly vulnerable. In addition to being subject to regional climatic variations, they have also been heavily influenced by shoreline mobilities, partially controlled by sea-level fluctuations. Studying these fluctuations is therefore essential for reconstructing the paleogeographic evolution of the coasts upon which societies depended. This thesis presents a synthesis of these variations and associated paleoenvironmental changes, supported by the contribution of new fieldwork results, a review of previously published research and modelling work based on the creation of Sea-Level Index Points, both in Abu Dhabi and across the entire southern shore of the Gulf. Adopting a geoarchaeological approach, the study integrates archaeological data to replace archaeological sites within their paleoenvironmental context. Despite relatively small metric variations, the results indicate significant impacts on shoreline morphology, marked by very low elevations. They also enable archaeological maps to be put into perspective. Lastly, they confirm the existence of relative sea-level variations resulting from landmass uplift and subsidence. The identified trajectories reveal substantial regional disparities and underscore the complexity and interplay of isostatic, neotectonic and diapiric mechanisms
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MacClenahan, Philippe. "Geographical variations in the Holocene chronology of western European coastal dunes in relation to climate, sea-level and human impact." Thesis, University of Ulster, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326312.
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Billy, Julie. "Morphologie et architecture d'une barrière composite paraglaciaire : l'isthme de Miquelon-Langlade (N- O Atlantique)." Thesis, Perpignan, 2014. http://www.theses.fr/2014PERP1214/document.
Анотація:
Cette thèse a pour objectif d’établir une vision globale et continue mer-terre-mer d’une barrière littorale paraglaciaire, en combinant une approche morphologique et architecturale. L’originalité de l’isthme de Miquelon-Langlade (NO Atlantique) entre les deux îles éponymes réside en sa diversité et complexité de systèmes (flèches, cordons littoraux, lagune) qui s’emboitent formant une barrière composite évoluant le long de deux façades ouvertes sur l’océan. Ce travail a été rendu possible grâce à l’association de données topographiques (GPS-RTK), de géophysique marine (sismique HR) et terrestre (géo-radar), sédimentaires (carottes, échantillons de surface) ainsi que des datations par OSL. L’étude de cette barrière a permis 1) d’identifier l’ensemble des dépôts d’une séquence paraglaciaire (dépôts de chute, bas niveau, augmentation et haut niveau marin); 2) de pointer l’importance de la géométrie des îles, du substratum rocheux ainsi que de la topographie héritée dans la formation de la barrière; 3) de définir l’architecture interne de beach ridges mixte sable-galet; et 4) de pointer le potentiel de ces systèmes en tant marqueur du paléo-niveau marin tout en proposant la première courbe de tendance de l’évolution du RSL pour l’Archipel de Saint-Pierre-et-Miquelon sur les derniers 3000 ans (+1mm/an). L’association de l’ensemble de ces informations a permis de proposer un schéma de mise en place de la barrière, depuis le retrait de la calotte (13 700 ans) jusqu’à sa forme actuelle, évoluant dans un contexte d’augmentation du RSL et de fort apport sédimentaire, tout en proposant une vision de détail de la formation de la plaine de beach ridges au cours des derniers 3000 ansThe purpose of this PhD thesis was to define a complete and continuous sea-land-sea view of a paraglacial coastal barrier system, combining morphological and architectural approaches. Particularity of the Miquelon-Langlade isthmus (NO Atlantic) lies in its diversity and complexity of systems (spits, beach ridges, and lagoon) that fit together to form a composite barrier prograding along two open coasts. Investigations of this barrier included topographic (RTK-GPS), ground-penetrating radar (GPR) seismic, sedimentary (cores, augers, samples) and chronologic (OSL) data collections. This study of this paraglacial composite barrier make possible 1) to characterize all deposits of the paraglacial sequence (FSST, LST, TST, HST); 2) to emphasize the primary influence of islands geometry, bedrock and inherited topography on the coastal progradational pattern; 3) to provide a better understanding of the internal architecture of depositional processes and driving mechanisms of mixed sand-and-gravel beach ridges; 4) to examine the potential of these mixed beach-ridge systems to record and preserve paleo-sea-level information, to produce the first sea level trends for the Saint-Pierre-et-Miquelon archipelago over the last 3000 years. The combination of all these data provide a model of development of the barrier since the ice sheet retreat (13 700 yrs) to its present form, in a context of RSL rise and high local glaciogenic sediment supply, and a detailed view of the formation of the beach ridge plain over the last 3000 yrs
Книги з теми "Relative Sea-Level Variations":
1
McClenahan, Philippe. Geographical variations in the holocene chronology of western Europe coastal dunes in relation to climate, sea-level and human impact. [S.l: The Author], 1997.
Частини книг з теми "Relative Sea-Level Variations":
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ARMENTROUT, JOHN M. "Relative Sea-Level Variations and Fault-Salt Response: Offshore Texas Examples." In Rates of Geologic Processes, Tectonics, Sedimentation, Eustasy and Climate - Implications for Hydrocarbon Exploration: 14th Annual, 1–7. SOCIETY OF ECONOMIC PALEONTOLOGISTS AND MINERALOGISTS, 1993. http://dx.doi.org/10.5724/gcs.93.14.0001.
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Vignudelli, Stefano, and Francesco De Biasio. "Coastal Sea Level Trends from a Joint Use of Satellite Radar Altimetry, GPS and Tide Gauges: Case Study of the Northern Adriatic Sea." In Geodetic Sciences - Theory, Applications and Recent Developments. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98243.
Анотація:
For the last century, tide gauges have been used to measure sea level change along the world’s coastline. However, tide gauges are heterogeneously distributed and sparse in coverage. The measured sea level changes are also affected by solid-Earth geophysics. Since 1992, satellite radar altimetry technique made possible to measure heights at sea independent of land changes. Recently various efforts started to improve the sea level record reprocessing past altimetry missions to create an almost 30 year-long combined record for sea level research studies. Moreover, coastal altimetry, i.e. the extension of altimetry into the oceanic coastal zone and its exploitation for looking at climate-scale variations of sea level, has had a steady progress in recent years and has become a recognized mission target for present and future satellite altimeters. Global sea level rise is today well acknowledged. On the opposite, the regional and local patterns are much more complicated to observe and explain. Sea level falls in some places and rises in others, as a consequence of natural cycles and anthropogenic causes. As relative sea level height continues to increase, many coastal cities can have the local elevation closer to the flooding line. It is evident that at land-sea interface a single technique is not enough to de-couple land and sea level changes. Satellite radar altimetry and tide gauges would coincide at coast if land had no vertical motion. By noting this fact, the difference of the two independent measurements is a proxy of land motion. In this chapter, we review recent advances in open ocean and coastal altimetry to measure sea level changes close to the coasts over the satellite radar altimetry era. The various methods to measure sea level trends are discussed, with focus on a more robust inverse method that has been tested in the Northern Adriatic Sea, where Global Positioning System (GPS) data are available to conduct a realistic assessment of uncertainties. The results show that the classical approach of estimating Vertical Land Motion (VLM) provides values that are almost half of those provided by the new Linear Inverse Problem With Constraints (LIPWC) method, in a new formulation which makes use of a change of variable (LIPWCCOV). Moreover, the accuracy of the new VLM estimates is lower when compared to the VLM estimated from GPS measurements. The experimental Sea Level Climate Change Initiative (SLCCI) data set (high resolution along track) coastal sea level product (developed within Climate Change Initiative (CCI project) that has been also assessed in the Gulf of Trieste show that the trends calculated with the gridded and along track datasets exhibit some differences, probably due to the different methodologies used in the generation of the products.
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ESCHARD, R., C. RAVENNE, P. HOUEL, and R. KNOX. "THREE-DIMENSIONAL RESERVOIR ARCHITECTURE OF A VALLEY-FILL SEQUENCE AND A DELTAIC AGGRADATIONAL SEQUENCE: INFLUENCES OF MINOR RELATIVE SEA-LEVEL VARIATIONS (SCALBY FORMATION, ENGLAND)." In The Three-Dimensional Facies Architecture of Terrigenous Clastic Sediments and Its Implications for Hydrocarbon Discovery and Recovery, 133–47. SEPM (Society for Sedimentary Geology), 1991. http://dx.doi.org/10.2110/csp.91.03.0133.
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Disiyona, Arya, and Awang H. Satyana. "Carbonate Characteristics of Banyu Urip, Kerendan, Arun, and Natuna D‐Alpha Fields: Cenozoic Isolated Carbonate Platforms as Major Reservoirs in Indonesia." In Cenozoic Isolated Carbonate Platforms—Focus Southeast Asia, 220–43. SEPM (Society for Sedimentary Geology), 2023. http://dx.doi.org/10.2110/sepmsp.114.09.
Анотація:
Situated at tropical latitudes with a humid paleoclimate, the area of the present-day Indonesian archipelago was very suitable for production and accumulation of carbonate sediment during much of the Cenozoic. Following early Paleogene rifting that resulted in development of horst and graben structures, the peak of carbonate production occurred from the late Oligocene to Mio–Pliocene. This paper summarizes several Indonesian isolated carbonate platforms that formed on marine horsts. Of these examples, Banyu Urip in Java, Kerendan in Kalimantan, and Arun Field in Sumatra have provided important contributions to Indonesian oil and gas production for the last few decades, whereas Natuna D-Alpha in the Natuna Sea will become a giant gas field in the future. To achieve the objective of characterizing Cenozoic carbonate platform reservoirs of Indonesia, this study reviews the Cenozoic carbonates in the East Java Basin, Kutei Basin, North Sumatra Basin, and Natuna area and places them in the context of the regional geology of Sundaland. Insights from previously published work are supplemented by new descriptions of cores, well-log analyses, and interpretations of two- and three-dimensional seismic facies analysis, well-log correlation, and sequence stratigraphy. These geological and geophysical data have been integrated with dynamic reservoir data to validate the geological and geophysical interpretations. The results reveal that the Indonesian carbonates of Banyu Urip, Kerendan, Arun, and Natuna D-Alpha are classic isolated carbonate platforms and can serve as examples to recognize reservoir character. Those platforms developed in the same general regional geologic setting relative to the Sundaland continent and share certain similarities, but local geologic variations and distinct processes gave each platform particular characteristics. Reservoir quality of the carbonate platforms is influenced by relative changes in sea level, the position relative to the shoreline or fully open-marine settings, and the influences of both regional and local tectonic events. The fields thus illustrate several conceptual models of carbonate reservoirs in isolated platforms. Understanding the character and variety of Indonesian reservoirs as related to their depositional processes and regional position provides insights for exploration and reservoir management of analogs elsewhere.
5
Lunt, Peter. "Tectono‐Stratigraphic Framework of Luconia Carbonates." In Cenozoic Isolated Carbonate Platforms—Focus Southeast Asia, 49–69. SEPM (Society for Sedimentary Geology), 2023. http://dx.doi.org/10.2110/sepmsp.114.08.
Анотація:
This paper describes the deposition of Miocene carbonates around Sarawak in a tectono-stratigraphic framework. The onset, termination, and location of the two main carbonate units, the Subis or Lower Cycle II limestones and the Luconia limestone, were controlled by tectonic processes, each beginning with a subsidence event, and terminated by influxes of siliciclastic sediments due to hinterland uplift. New data are presented on the intra–late Miocene decline of Luconia Limestone platforms that is correlated to the uplift of onshore Sarawak (Tinjar Province) and renewed siliciclastic sedimentation, which is dated as being at the same time as major uplift in northern Borneo. Miocene sedimentation around Sarawak was controlled mostly by extensional tectonics with several rapid subsidence events, which produced transgressive unconformities with mappable focal areas. Away from these focal areas, the contrast in facies, before and after the event, gradually diminishes in a predictable manner. This property of the unconformity is governed by Walther’s Law in that one well or field section cannot be exempt from the mappable trends in facies contrast observed in surrounding wells. This relationship constrains the interpretation of seismic, mapping, and analytical data, as illustrated by an example of a misdated unconformity that previously violated this balance of facies change in space and time. The tectono-stratigraphic model is a refinement of an existing empirical scheme devised in the area, with units called “Cycles” (Cycles I to VIII). This evidence-based framework is argued to be a genetic description of depositional units that developed in a dynamically evolving depocenter, subject to geographic rotation and relative variations in sea level that were dependent on location. This shifting basin configuration precludes use of a passive margin sequence stratigraphic approach, which assumes and requires a constant proximal to distal sedimentary direction and steady basement subsidence.
6
Maun, Anwar, and Dianne Fahselt. "Dune systems in relation to rising seas." In The Biology of Coastal Sand Dunes. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780198570356.003.0018.
Анотація:
Beaches and associated dunes are constituted of unconsolidated materials, such as sand, and thus are low-strength land forms less robust than rocky cliffs (van der Meulen et al. 1991). It is estimated that 70% of sand-based coastlines in the world are presently subject to erosion (Bird 1985; Wind and Peerbolte 1993). However, natural dune systems are inclined to adjust after stress without permanent damage (Brown and McLachlin 2002), and when stabilized by plant cover they offer a first line of coastal defence against assault from wave action (Wind and Peerbolte 1993; Broadus 1993; De Ronde 1993). Natural self-sustaining dune systems interact with the sea and closely reflect changes in sea levels. At any given time no single sea level characterizes all oceans, that is, the resting position of the ocean surface, or geoid, is not uniformly elevated over the earth. Eustatic sea levels, free of influence from tides, waves and storms, thus vary from place to place as well as over time. Satellite altimetry, which permits more accurate as well as more numerous observations than older tide-gage methods of measuring sea levels, shows that the ocean is actually a spheroid modified by depressions and elevations. For example, in parts of the Indian Ocean sea levels are as much as 70 m lower than the global mean and in the North Atlantic 80 m higher (Carter 1988). Climate is governed by long-term periodic variations in the earth’s orbit that effect changes in solar radiation and, consequently, also in sea levels (Bartlein and Prentice 1989; Woodroffe 2002). As a result, ice ages repeatedly alternate with periods of interglacial warming in which ice masses contract and sea levels increase. Most of the time that has passed since the Cambrian period—approximately 500 million years—sea levels, although fluctuating on several timescales, have been higher than they are today. Because of the difficulties in documenting conditions so far in the distant past estimates of these sea levels vary considerably, but those shown in Fig. 13.1, based on different kinds of evidence, are representative of attempts at reconstruction (personal communication RA Rohde 2008).
7
Golam Rabbani, Md, Md Nasir Uddin, and Sirazoom Munira. "Changing Climatic Hazards in the Coast: Risks and Impacts on Satkhira, One of the Most Vulnerable Districts in Bangladesh." In Climate Issues in Asia and Africa - Examining Climate, Its Flux, the Consequences, and Society's Responses [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98623.
Анотація:
Changes in the climate due to anthropogenic and natural variation are indicated by parameters including temperature and rainfall. Climate change variability with changing trends of the two have been unpredictable and unprecedented globally leading to changing weather patterns, natural disasters, leading to sectoral impacts on food and water security, livelihood, human health among others. This research analyses the changing patterns of these parameters over the last 35/37 years of Satkhira district of Bangladesh to assess the state and trend across spatial and temporal dimensions. Such, the study validates to rationalize the observed seasonal changes that persist in Satkhira of Bangladesh. Both in terms of intensity and frequency of the occurrences of natural disasters, the series of natural events have been triangulated, with impacts and vulnerability being assessed from temperature variations, erratic rainfall, cyclone, flood and water logging etc. The study’s prime contribution remains in attribution of climate change in relation contextual circumstances in the region including sea level rise, salinity intrusion. Therefore, the risk and climatic hazards and its resulting impacts over time has been assessed to draw deeper connection between theoretical and practical values. The series of analyses also draw conclusion that assets are at risk from changing climatic condition.
8
Whittaker, Robert J., José María Fernández-Palacios, and Thomas J. Matthews. "Island environments." In Island Biogeography, 39–56. 3rd ed. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780198868569.003.0003.
Анотація:
Abstract ‘Island environments’ examines variation in environmental properties of islands, highlighting the range of distinctive classes of island in terms of geology, topography, and climate, and how they contrast with mainland environments. It discusses edaphic properties linked to their distinctive geological origins, noting the importance of marine and atmospheric subsidies to their nutrient cycles. It describes island climate regimes and climate zonation compression on high islands and shows that island position in relation to large-scale features of the climate, marine and atmospheric currents, and hurricane systems, are all key features of island environments. It highlights the importance of continued volcanism and mega-landslides for many islands. It describes how Quaternary climate change has impacted island environments both directly and through fluctuations in sea level, sometimes to slightly higher and for lengthy periods much lower levels than present. Finally, it briefly introduces the theme of anthropogenic environmental change on islands.
9
Turck, John A., Victor D. Thompson, and Victor D. Thompson. "Human-Environmental Dynamics of the Georgia Coast." In The Archaeology of Human-Environmental Dynamics on the North American Atlantic Coast, edited by Leslie Reeder-Myers, John A. Turck, and Torben C. Rick, 164–98. University Press of Florida, 2019. http://dx.doi.org/10.5744/florida/9780813066134.003.0007.
Анотація:
This chapter synthesizes and evaluates settlement and subsistence patterns in relation to landscape change for Native American occupations of the Georgia coast in the southeast USA. Dynamic coastal processes of the region have altered the topography and distribution of resources, including those important to humans. These processes were neither uniform in space nor time, with variations leading to the creation of micro-habitats. We assess these habitats, individually and as part of a complex whole, to better elucidate the nature of human–environmental interactions and socio-ecological systems. Understanding this complex relationship helps reveal social trajectories and environmental impacts on the ecosystem of coastal groups. This research, based on historical ecology, is used as a departure point to discuss the future of humans along changing coastlines. We argue that past peoples dealt with similar coastally-related issues as today, such as sea level fluctuations or changes to once productive resources. The knowledge archeologists have gained concerning past human–environmental interactions must be conveyed to the public, including policy-makers, to transform society for the better.
10
Brockmann, Jan Martin, Moritz Borlinghaus, Christian Neyers, and Wolf-Dieter Schuh. "On the Coestimation of Long-Term Spatio-Temporal Signals to Reduce the Aliasing Effect in Parametric Geodetic Mean Dynamic Topography Estimation." In International Association of Geodesy Symposia. Berlin, Heidelberg: Springer Berlin Heidelberg, 2023. http://dx.doi.org/10.1007/1345_2023_224.
Анотація:
AbstractThe geodetic estimation of the mean dynamic ocean topography (MDT) as the difference between the mean of the sea surface and the geoid remains, despite the simple relation, still a difficult task. Mainly, the spectral inconsistency between the available altimetric sea surface height (SSH) observations and the geoid information causes problems in the separation process of the spatially and temporally averaged SSH into geoid and MDT. This is aggravated by the accuracy characteristics of the satellite derived geoid information, as it is only sufficiently accurate for a resolution of about 100 km.To enable the direct use of along-track altimetric SSH observations, we apply a parametric approach, where a $$C^1$$ C 1 -smooth finite element space is used to model the MDT and spherical harmonics to model the geoid. Combining observation equations for altimetric SSH observations with gravity field normal equations assembled from dedicated gravity field missions in a least-squares adjustment, allows for a joint estimation of both – i.e. the MDT and an improved geoid.In order to enable temporal averaging and to obtain a proper spatial resolution, satellite altimetry missions with an exact repeat cycle are combined with geodetic missions. Whereas the temporal averaging for the exact repeat missions is implicitly performed due to the regular temporal sampling, aliasing is introduced for the geodetic missions, because of the missing repeat characteristics. In this contribution, we will summarise the used approach and introduce the coestimation of long-term temporal sea level variations. It is studied how the additional spatio-temporal model component, i.e. linear trends and seasonal signals, reduces the aliasing problem and influences the estimate of the MDT and the geoid.
Тези доповідей конференцій з теми "Relative Sea-Level Variations":
1
Ezer, T., and W. B. Corlett. "Analysis of relative sea level variations and trends in the Chesapeake Bay: Is there evidence for acceleration in sea level rise?" In OCEANS 2012. IEEE, 2012. http://dx.doi.org/10.1109/oceans.2012.6404794.
2
Suursaar, Ulo, and Tarmo Kall. "Interpretation of relative sea level variations at tide gauges using results from four estonian precise levellings and land uplift models." In 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS). IEEE, 2017. http://dx.doi.org/10.1109/igarss.2017.8128378.
3
Bilge, H. Tolga, Berna Unutmaz, A. Anil Yunatci, Ipek Yunatci, and K. Onder Cetin. "Liquefaction Triggering Response Under Wave-Induced Cyclic Loading." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-80123.
Анотація:
Cyclic response of saturated sands has become one of the most popular topics in geotechnical earthquake engineering due to the consequent damages of earthquakes. Related to this topic, detailed performance of offshore structures founded on saturated sands under the effect of cyclic loads carries vital economic importance. It is well-known that besides seismic loading; storm, wind and/or submarine slope failures have direct effect on the strength and deformation behavior of soils through induced sea-level variations. This study summarizes the results of a series of cyclic triaxial tests performed to simulate the behavior of fully-saturated coarse grained sands under wave-induced cyclic loading. Evaluating the excess pore water pressure generation and shear strain accumulation response along with the number of cycles required for liquefaction triggering for sands, having different relative densities, and being subjected to various cyclic shear stress ratios (CSR), the following observations are made; i) number of cycles to liquefaction increases with increasing relative density and decreasing CSR, ii) for medium dense foundation and backfill soils, liquefaction is not triggered for CSR values less than 0.1 under reasonable number of cycles, and iii) number of cycles to liquefaction decreases significantly for soils subjected to CSR values exceeding of 0.25. These results were used to express the effects of the variation in water level and liquefaction triggering response in terms of in-situ test data, wave height and number of waves for the granular backfill of a sample offshore structure.
4
Jenkins, Sean C., and David G. Bogard. "The Effects of the Vane and Mainstream Turbulence Level on Hot Streak Attenuation." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-54022.
Анотація:
This paper discusses the effects of varying pitch position on the attenuation of a simulated hot streak in a vane cascade under conditions of low and high turbulence. Measurements describe the effect of both small and large changes in pitch away from the stagnation line as evidenced by hot streak variations in the wake and at the trailing edge. Under both turbulence conditions, the vane serves to increase or decrease the attenuation rate depending on the location of the hot streak relative to the vane due to isolating of the hot streak core by the vane wall. Additional attenuation resulted due to the action of the wake on the hot streak.
5
Davenport, Mike, Rufat Guliyev, Kasim Sadikoglu, Pavel Gramin, and Adrian Zett. "DETERMINATION OF RESIDUAL OIL SATURATION IN A WATER AND GAS FLOODED GIANT OIL RESERVOIR USING CORE, CONVENTIONAL AND PULSED NEUTRON LOGS." In 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0097.
Анотація:
The understanding of residual saturation in an oil field in mid-development is essential for estimating the cumulative production achievable, optimizing the future production mechanisms planned for infill targets, development of adjacent reservoir levels and optimizing the design of future facilities. The ACG (Azeri, Chirag, Gunashli) field is a giant oil field located about 120 km offshore in the South Caspian Sea, Azerbaijan. The field consists of multiple stacked clastic reservoirs including the Fasila and Balakhany formations, each with variable oil water contacts, and variable presence and fill level of gas caps. The Fasila reservoirs have been nearly fully developed. Both down flank water injection and crestal gas injection have been employed to drive oil towards producers. These two processes result in different residual oil “trapping” mechanisms which have been explored by logging and coring. Future development of overlying reservoirs can be optimized if we understand the effectiveness of these mechanisms to improve oil recovery and understand produced fluid compositions to enable facilities optimization to handle them. Established techniques to measure the residual oil saturation in a live field depletion, such as conventional open hole logging, pulsed neutron logging and direct core measurements have been employed. This paper investigates the methodology of each technique and the comparison of the magnitude and uncertainty of the saturations obtained. The sands in the ACG main reservoirs are relatively massive and high Net-to-Gross (NTG), however their clay content and distribution is quite variable leading to a range of rock types which behave differently under fluid sweep, and the presence of both intra reservoir sealing shales and lateral sand quality variations lead to a complex pattern of sweep behavior. It was considered that conventional core would be the principle measurement, with the most direct estimation of downhole fluid conditions as well as achieving all other coring objectives. Core was acquired on two pilot wells, one behind the water flood front and another behind the expanding crestal gas cap. Several innovative core analysis techniques were employed. A full conventional log suite was acquired in both wells as well as an open hole pass of a multi detector pulsed neutron log in the crestal gas swept well. The analysis of all this data has led to some interesting conclusions. Previous core flood experiments had led the team to believe gas is more efficient than water in terms of lowering residual oil saturation and reaching higher recovery factors. The new core demonstrated that such low residual oil saturations are achieved more slowly than originally thought, though it didn't change the view of efficiency of gas displacement relative to water. It is also likely that reservoir heterogeneity has had a bigger impact on the variation in residual oil saturation between layers than reservoir quality itself.
6
Hørte, Torfinn, Massimiliano Russo, Michael Macke, and Lorents Reinås. "Benefit of Measurements and Structural Reliability Analysis for Wellhead Fatigue." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10932.
Анотація:
Structural Reliability Analysis (SRA) methods have been applied to marine and offshore structures for decades. SRA has proven useful in life extension exercises and inspection planning of existing offshore structures. It is also a useful tool in code development, where the reliability level provided by the code is calculated by SRA and calibrated to a target failure probability. The current analysis methods for wellhead fatigue are associated with high sensitivity to variations in some input parameters. Some of these input parameters are difficult to assess, and sensitivity screening is often needed and the worst case is then typically used as a basis for the analysis. The degree of conservatism becomes difficult to quantify, and it is therefore equally difficult to find justification to avoid worst case assumptions. By applying SRA to the problem of wellhead fatigue, the input parameters are accounted for with their associated uncertainty given by probability distributions. In performing SRA all uncertainties are considered simultaneously, and the probability of fatigue failure is estimated and the conservatism is thereby quantified. In addition SRA also provides so-called uncertainty importance factors. These represent a relative quantification of which input parameter uncertainties contribute the most to the overall failure probability, and may serve well as guidance on where possible effort to reduce the uncertainty preferably should be made. For instance, instrumentation may be used to measure the actual structural response and thus eliminate the uncertainty that is associated with response calculations. Clearly measurements obtained from an instrumented system will have its own uncertainty. Other options could be to perform specific fatigue capacity testing or pay increased attention to logging of critical operational parameters such as the cement level in the annulus between the conductor and surface casing. This article deals with the use of measurements for fatigue life estimation. Continuous measurements of the BOP motion during the drilling operations have been obtained for a subsea well in the North Sea. These measurements are used both in conventional (deterministic) analysis and in SRA (probabilistic analysis) for fatigue in the wellhead system. From the deterministic analysis improved fatigue life results are obtained if the measured response replaces the response obtained by analysis. Furthermore, SRA is used to evaluate the appropriate magnitude of the design fatigue factor when fatigue analysis is based on measured response. It is believed that the benefit from measurements and SRA serve as an improved input to the decision making process in the event of life extension of existing subsea wells.
7
Green, D., D. A. Lawrence, and M. Al Mansouri. "The Influence of Relative Sea Level Variation on Depositional Settings of the Late Jurassic Arab Formation in a Giant Gas Field, United Arab Emirates." In Fourth Arabian Plate Geology Workshop. Netherlands: EAGE Publications BV, 2012. http://dx.doi.org/10.3997/2214-4609.20142800.
8
Kowalczyk, Kamil, and Joanna Kuczynska-Siehien. "Testing Correlation between Vertical Crustal Movements and Geoid Uplift for North Eastern Polish Border Areas." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.206.
Анотація:
Long time span of observations from GNSS permanent stations can be used in the development of models of vertical crustal movements. The absolute vertical crustal movement related to the ellipsoid consists of the observed movement with relation to the mean sea level, the eustatic movement and the geoid uplift. The geoid uplift can be determined from GRACE satellite mission observations. The calculated parameters can be compared with the theoretical ones. The aim of this study is to check the correlation between vertical crustal movements and a geoid height variations determined from satellite data. GNSS data, levelling data and satellite observations for north eastern Polish border areas were used as a case study. Temporal variations of geoid were calculated based on the geopotential models from GRACE satellite observations. The obtained results give an overview of a possibility of the proposed method usage.
9
Bunker, R. S., G. M. Laskowski, J. C. Bailey, P. Palafox, S. Kapetanovic, G. M. Itzel, M. A. Sullivan, and T. R. Farrell. "An Investigation of Turbine Wheelspace Cooling Flow Interactions With a Transonic Hot Gas Path—Part 1: Experimental Measurements." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59237.
Анотація:
The desire for higher power output combined with lower fuel consumption has focused recent design and research attention on the interaction of required secondary systems cooling flows with the turbine hot gas path. The flow physics associated with the rotor-stator wheelspaces, and in particular the trench and buffer cavity areas just inboard of the hot gas path, demand an increased level of design sophistication to account for the unsteady fluid and thermal effects associated with periodic vane wakes, circumferential pressure gradients, purge flows, and blade lead edge blockages. Part 1 of this study utilizes a wheelspace sector cascade rig for the purpose of gathering fundamental data on flow and thermal effects in a nonrotating environment. This experimental rig is a simplified screening tool for the investigation of basic geometry and flow effects that maintains the bulk of the correct flow physics in the absence of rotation. The test rig is also a validation data generation device for the unsteady CFD modeling efforts described in Part 2. The present cascade is composed of a five passage annular sector of a transonic turbine inlet guide vane, a complete sector of the upper wheelspace, buffer and trench cavities, and equivalent flow blockages for a blade row represented as leading edge cylinders. The geometry is three-dimensional including all sealing features of the wheelspace. The vane and blade rows can be clocked to any relative position. Secondary cooling flows are adjustable for the wheelspace purge flow and the leakage flow across the vane support. Detailed measurements in the form of static pressures throughout the interaction region, surface temperature distributions, and buffer cavity air temperatures are presented for various clocked positions. The circumferential pressure distribution peak-to-peak variations just aft of the vane are here as much as 18%. These variations are key to the resulting forcing of hot gas inboard of the rim seal. The blade leading edge bow wave is found to have an equal or even greater influence in generating this peak-to-peak variation than the vane trailing edge wake. Buffer cavity cooling effectiveness levels vary with the clocked positions and decrease as cylinder size is increased. Significantly, the effect of the leading edge blockage can reduce buffer cavity cooling effectiveness by a factor of 0.1.
10
Van Zante, Dale, Jenping Chen, Michael Hathaway, and Randall Chriss. "The Influence of Compressor Blade Row Interaction Modeling on Performance Estimates From Time-Accurate, Multi-Stage, Navier-Stokes Simulations." In ASME Turbo Expo 2005: Power for Land, Sea, and Air. ASMEDC, 2005. http://dx.doi.org/10.1115/gt2005-68463.
Анотація:
The time-accurate, multi-stage, Navier-Stokes, turbomachinery solver TURBO was used to calculate the aero performance of a 2 1/2 stage, highly-loaded, high-speed, axial compressor. The goals of the research project were to demonstrate completion times for multi-stage, time-accurate simulations that are consistent with inclusion in the design process, and to assess the influence of differing approaches to modeling the effects of blade row interactions on aero performance estimates. Three different simulation setups were used to model blade row interactions: 1.) single passage per blade row with phase lag boundaries, 2.) multiple passages per blade row with phase lag boundaries, and 3.) a periodic sector (1/2 annulus sector). The simulations used identical inlet and exit boundary conditions and identical meshes. To add more blade passages to the domain, the single passage meshes were copied and rotated. This removed any issues of differing mesh topology or mesh density from the following results. The 1/2 annulus simulation utilizing periodic boundary conditions required an order of magnitude less iterations to converge when all three simulations were converged to the same level as assessed by monitoring changes in overall adiabatic efficiency. When using phase lag boundary conditions the need to converge the time history information necessitates more iterations to obtain the same convergence level. In addition to convergence differences, the three simulations gave different overall performance estimates where the 1/2 annulus case was 1.0 point lower in adiabatic efficiency than the single passage phase lag case. The interaction between blade rows in the same frame of reference set up spatial variations of properties in the circumferential direction which are stationary in that reference frame. The phase lag boundary condition formulation will not capture this effect because the blade rows are not moving relative to each other. Thus for simulations of more than two blade rows and strong interactions, a periodic simulation is necessary to estimate the correct aero performance.